阅读说明：本技术 制备基于硅氧烷的聚合物液体材料的方法和由其制成的材料 (Method for preparing siloxane-based polymeric liquid materials and materials made therefrom ) 是由 M.凯贝尔 A.斯托贾诺维克 W.马尔费特 A.努尔 于 2019-06-04 设计创作，主要内容包括：一种由芯-壳型构造的分子构件形成的聚合物液体材料,其中各构件由超支化聚硅氧烷芯和外围附接到其的官能硅氧烷壳组成,所述材料包括桥接氧部分(Si-O-Si)、可水解的烷氧基部分(Si-O-R)、和有机官能部分(R’-Si-)和(R_1-Si-R_2)、以及少于0.5质量百分比的羟基部分(Si-OH)。所述芯具有范围为1.3至2.7的聚合度DP_芯,所述壳由R’-取代的硅氧烷部分形成并且具有范围为0.3至2.5的聚合度DP_壳。所述芯中全部Si原子的至少75原子百分比仅键合到烷氧基或桥接氧,其余部分各自键合到3个氧和1个碳。所述材料中总Si对可水解的自由烷氧基的摩尔比为1:1.25至1:2.75,并且所述材料具有范围为10-100’000cP的粘度。制备所述聚合物液体材料的方法依赖于首先形成超支化聚硅氧烷芯、随后积聚官能硅氧烷壳。为此,开发了基于在无水环境中加入化学计量量的乙酸酐的反应方案。(A polymeric liquid material formed from molecular building blocks of core-shell type construction, wherein each building block consists of a hyperbranched polysiloxane core and a functional siloxane shell peripherally attached thereto, said material comprising bridging oxygen moieties (Si-O-Si), hydrolysable alkoxy moieties (Si-O-R), and organofunctional moieties (R' -Si-) and (R ` 1 ‑Si‑R 2 ) And less than 0.5 mass percent of hydroxyl moieties (Si-OH). The core has a degree of polymerization DP in the range of 1.3 to 2.7 Core The shell is formed of R' -substituted siloxane moieties and has a degree of polymerization DP in the range of 0.3 to 2.5 Shell . At least 75 atoms of all Si atoms in the coreSub-percentages are bonded only to alkoxy groups or bridging oxygens, the remainder being bonded to 3 oxygens and 1 carbon each. The material has a molar ratio of total Si to hydrolysable free alkoxy groups of from 1:1.25 to 1:2.75, and has a viscosity in the range of from 10 to 100'000 cP. The method of making the polymeric liquid material relies on first forming a hyperbranched polysiloxane core followed by accumulation of a functional siloxane shell. To this end, reaction schemes based on the addition of stoichiometric amounts of acetic anhydride in an anhydrous environment were developed.)

1. a method of preparing a polymeric liquid material formed from molecular building blocks of a core-shell type construction, each building block consisting of a hyperbranched polysiloxane core and a functional siloxane shell peripherally attached to the core, the method comprising the steps of:

a) at least one tetraalkoxysilicon Si (OR)₄And optionally the following functional premixes in monomeric or oligomeric form with DP as desired_CoreA first stoichiometric amount of acetic anhydride is selected to be added together in the presence of a catalyst to the reaction vessel, wherein R is an unbranched or branched alkyl group having up to four carbon atoms:

-an R "-organicFunctional trialkoxysilanes R' -Si (OR)₃And optionally R₃,R₄-organofunctional dialkoxysilanes R₃-Si(OR)₂-R₄(ii) a Or

-a mixture of different R' -organofunctional trialkoxysilanes and optionally at least one R₃,R₄-organofunctional dialkoxysilanes;

b) heating the reaction mixture provided in step a) in an anhydrous inert atmosphere with stirring until the desired reaction temperature is reached and distilling off the resulting acetate reaction products until the reaction and the flow of distillate cease, thereby forming the hyperbranched polysiloxane core;

c) the following are mixed with DP according to desire_ShellA second stoichiometric amount of acetic anhydride selected is added together, optionally in the presence of a catalyst, with constant stirring, to the hot reaction mixture formed in step b) to initiate the selective accumulation of the functional siloxane shell on the core produced in step b), wherein additional acetate is formed and distilled off, and the reaction is continued until distillate flow is once again stopped:

an R '-organofunctional trialkoxysilane R' -Si (OR)₃And optionally R₁,R₂-organofunctional dialkoxysilanes R₁-Si(OR)₂-R₂Or is or

-a mixture of different R' -organofunctional trialkoxysilanes and optionally at least one R₁,R₂-an organofunctional dialkoxysilane,

wherein:

r 'and R' are independently selected substituents each of which can be represented by L-Z, wherein

L is selected from-C₆H₄-、-C₆H₄-CH₂-、-CH₂-CH₂-C₆H₄-CH₂-and- [ (CH)₂]_n-wherein n ═ 0, 1,2, 3, 4; and

-Z is a terminal functional group selected from:

wherein R is selected from-H, -CH₃、-C₂H₅、-C₃H₈、-C₄H₁₀and-C₆H₅；

Or Z is- [ (CH)₂]_m-CH₃Wherein m is 0, 1,2, … …, 11; and

-wherein R is₁、R₂、R₃And R₄Is independently selected from-CH₃、-C₂H₅、-C₆H₅、-C₆H₁₁、-CH＝CH₂、-CH₂-CH₂-Cl and-C₅H₅The substituent(s) of (a),

provided that (R', R) of the triplet₁、R₂) And (R', R)₃、R₄) Are not identical;

d) optionally, building an additional functional layer in the shell by repeating the addition and reaction scheme described in step c at least once;

e) optionally, removing low molecular reaction products and/or residual starting materials in the reaction mixture by vacuum distillation via gradually reducing the pressure inside the reaction vessel and maintaining the final pressure in the range of 5 to 250 mbar for a period of 10-120 minutes,

f) cooling and separating the polymeric liquid material thus obtained;

wherein steps a) to e) are carried out in the same reaction vessel.

2. The method of claim 1, wherein the functional pre-mix is zero.

3. The method of claim 1 or 2, wherein R is methyl or ethyl.

4. The process according to one of claims 1 to 3, wherein the reaction temperature of steps b) to e) is in the range of 70 to 170 ℃, preferably in the range of 100 to 150 ℃, and most preferably in the range of 120 to 140 ℃, and the pressure during steps b) to d) is in the range of 0.1 to 2 bar, preferably in the range of 0.5 to 1.4 bar, and most preferably in the range of 0.9 to 1.2 bar.

5. The process according to claim 1 to 4, wherein the tetraalkoxysilicon (OR)₄Tetraethoxysilane (TEOS) or Tetramethoxysilane (TMOS) or mixtures of monomers and oligomers thereof.

6. The process according to any one of claims 1 to 5, wherein the acetate ester reaction product is removed from the system by passing it through a distillation column comprising a plurality of theoretical plates in such a manner that: the lower boiling reaction product in solution is separated from the higher boiling residual reactant, whereby the latter is continuously fed back into the reaction mixture.

7. Process according to one of claims 1 to 6, in which the catalyst is chosen from Ti (OR ")₄OR Zn (II) alkoxide Zn (OR')₂Wherein R ═ CH₂CH₃、-CH(CH₃)₂、-CH₂CH₂CH₃、-C(CH₃)₃、-CH₂CH₂CH₂CH₃(ii) a Or the catalyst is Ti (O-Si (CH)₃)₃)₄Wherein the amount of catalyst is between 0.01 and 1.5% based on moles of total alkoxysilane precursor used in the core growth step.

8. The method according to one of claims 1 to 7, wherein R' is selected from the following groups:

i)R'＝-C₆H₅、-CH＝CH₂，

ii) R' ═ L-Z and L ═ CH₂-and Z ═ CH- [ (CH)₂]_p-CH₃Wherein p is 0, 1,2, 4, 6, 8, 10, 12, 14,

iii) R' is L-Z and L is-CH₂CH₂CH₂- (n-propyl) and Z ═ Br, -Cl, -I, -SH, -OH, -NH₂NH- (BOC), -NH- (FMOC), -2-oxetanyl, -methoxy- (2-oxetanyl), -N₃、-SO₃R、-PO₃R₂-acrylate, -methacrylate, -ethacrylate, -propylacrylate, -butylacrylate, or

iv) R ═ L-Z and L ═ CH₂Z is vinyl, acrylate, methacrylate, ethacrylate, propylacrylate, butylacrylate,

and wherein R₁And R₂Are identical and are selected from the group consisting of-CH₃、-C₆H₅and-CH ═ CH₂Or wherein R is₁＝-CH₃And R is₂＝-CH＝CH₂。

9. A polymeric liquid material prepared by the method of claim 2, the material being formed of molecular building blocks of core-shell type construction, each building block consisting of a hyperbranched polysiloxane core and a functional siloxane shell peripherally attached to the core,

the material comprises less than 0.5 mass percent of hydroxyl moieties (Si-OH),

the core has a degree of polymerization DP in the range of 1.3 to 2.7, in particular 1.5 to 2.5_Core，

The shell is formed of R' -substituted siloxane moieties and optionally R1-, R2-substituted siloxane moieties and has a degree of polymerization DP in the range of 0.3 to 2.5, particularly 1.0 to 2.3_Shell，

Wherein the molar ratio of total silicon to hydrolysable free alkoxy groups in the material is 1:1.25 to 1:2.75,

wherein the material has a viscosity in the range of 10 to 100'000cP,

and wherein the core is comprised of non-organofunctional siloxane moieties comprising

-a non-organofunctional end-bonded siloxane moiety of the formula (Q)¹Species (speciation)

And/or

-a non-organofunctional disiloxane moiety of the formula (Q2 species)

And/or

-a non-organofunctional trisiloxane moiety of the formula (Q)³Species)

And/or

-a non-organofunctional tetrasiloxane moiety of the formula (Q)⁴Species)

And wherein the shell is comprised of:

-a mono-organofunctional end-bonded siloxane moiety (T) of the formula¹Species)

And/or

A mono-organofunctional disiloxane moiety (T) of the formula²Species)

And/or

A mono-organofunctional trisiloxane (T) of the formula³Species) moiety

And optionally

-a terminally bonded diorganofunctional siloxane of the formula (D)¹Species) moiety

And/or

A diorganofunctional disiloxane of the formula (D)²Species) moiety

Wherein R, R' and R₁And R₂Is as defined in claim 1.

10. The polymeric liquid material according to claim 9, wherein the relative atomic ratio of T to Q species ranges from 0.03:1 to 1:1, preferably from 0.03:1 to 0.75:1, and most preferably from 0.05:1 to 0.5: 1.

11. A hydrolysate obtainable by reacting the polymeric liquid material according to claim 9 or 10 with a predetermined amount of water or with a predetermined amount of a water-solvent mixture.

12. Use of a polymeric liquid material according to one of claims 9 to 11 or a corresponding hydrolysate according to claim 7 in a coating or adhesive formulation or as a coupling agent mediating the incorporation of fillers into a polymer matrix.

13. Use of the polymeric liquid material according to one of claims 9 to 11 or the corresponding hydrolysate according to claim 7 as precursors of sol-gel chemistry techniques for the preparation of organofunctional gels and inorganic/organic nanocomposites and aerogels and xerogels derived therefrom.

Technical Field

The present invention relates generally to a method of preparing polymeric liquid materials formed from molecular building blocks of core-shell architecture (architecture) and materials made therefrom.

Background

With the progress of the nano era, science is targeting the following novel preparation methods: allowing for improved control of the chemical building block-thereby linking atoms with nanoscale dimensions. The creation of such novel functional materials via design (creation) bridges the interface from molecular to nanomaterial and from polymer to material science. FIG. 1 shows a general classification of molecules and nanoscale building blocks in terms of size. Molecular Building Blocks (MBBs) typically consist of tens to hundreds of atoms and are at most a few nanometers in size. Depending on their chemistry and compactness, they are often liquids under ambient conditions. This is a well-defined distinguishing feature from nanomaterials, which are solid at room temperature and are composed of thousands of millions of atoms. As shown in the figure, there is no clear demarcation between those material classes and there is some overlap around 1 nm.

According to IUPAC, nanotechnology involves novel materials with dimensions in the size range of about 1nm to 100nm, which can be quite different from macroscopic materials in structure, properties and interactions. The so-called bottom-up approach offers the greatest flexibility for controlling new functionalities (functionalities) and final material properties, where molecular precursors have often produced nanoscale components (NBBs) such as nanoparticles and the like through chemical reactions in the past. In this particular field of technology, the assembly of NBB typically starts with an atomic or small molecule precursor. Typical examples include

-polymeric nanoparticles prepared from organic monomers by emulsion polymerization,

noble metal nano-objects obtained by chemical reduction from salt precursors in the corresponding solutions,

(semi) metal oxide nanoparticles or "colloidal sols" synthesized from the corresponding (semi) metal salts or small molecule organometallic precursors such as alkoxides, acetylacetonates, etc.

Recently, researchers have been targeting controlled bottom-up synthesis of novel functional materials at the molecular level by precisely controlling the structure-forming steps at the interface between small molecules and nano-or even macro-scale. In the case of, for example, organometallic frameworks (MOFs), molecular interactions are specifically selected and designed to combine organic precursors and metal/metal oxide precursors in such a way that: macroscopically large crystalline compounds are obtained, controlled at the molecular level. Clearly, molecular design approaches grant access to an unprecedented diversity of material properties. Similar concepts pursued in colloidal chemistry and polymer chemistry are at the forefront of material science today.

In the state of the art, the introduction of specific chemical functionalities in both (MBB or NBB) is achieved by introducing functional species throughout the structure or by selective grafting on the surface of the core block. In nanotechnology, the term core-shell depicts the following nano-objects: a second, usually functional, compound layer is grown on the core. The term core-shell has not been recognized in molecular and polymer science, however in view of the strong similarity we extend the "core-shell" term herein to MBB and hyperbranched siloxane polymer science.

In the classical representation of dendritic MBBs with high compactness, star polymers are a subclass of polymeric materials, in which the dendritic arms made of a given polymer chemistry emanate from a core onto which they are grafted. DE 102008063070 a1 describes star polymers in which the peripheral polymer arms have been functionalized by anionic or cationic groups chemically linked via silanes to improve surfactant properties, but the main constituent is non-silicon based. Furthermore, US 2004/0122186 specifies the use of two and four arm core-spacer-end group materials. The compounds described herein are chemically linked by hydrosilylation and include different molecular architectures, i) a bisphenol-a organic core, a dimethylsiloxane spacer, and an organic group (epoxy, methylstyrene, cyclopentadienyl) terminal, ii) a tetrakis (dimethylsilyl) -siloxane core, a dicyclopentadiene spacer (or terminal), followed by a second tetramethyldisiloxane spacer and an epoxy or unsaturated terminal. US 2007/19773 a1 describes a similar class of materials based on 3-and 6-fold symmetry of polycyclic aromatic hydrocarbon organic cores, siloxane spacer arms, and reactive organic end groups. In US 2010/0305293, pure siloxane star polymer compounds are proposed without the use of "non-silicon" organic components. In the current state of the art, star polymers comprising silanes and siloxanes are generally obtained by successive molecular coupling reactions, each extending the shell by one building block unit. Coupling is most often achieved by hydrosilylation chemistry and produces polymers of moderate to high molecular weight that are well defined in composition and range in size from angstroms to a single nanometer.

In contrast, organic/inorganic hybrid materials and NBB are available through a rich variety of preparative techniques. For example, the solvent-gel technique operates in a liquid solution, starting with a colloidal suspension of molecular or oligomeric precursors, resulting in the spontaneous formation of the nanoparticulate component. In one aspect, the sol can be prepared in situ from oligomeric polyhydroxymetallate (e.g., silicic acid oligomers in the case of silica) by hydroxyl coupling and condensation reactions that control solvent, pH, and the like. They are used as classical NBB to produce porous metal oxides and hybrid materials. The more widely adopted route to metal oxide sols comes from metal alkoxides such as TEOS, TMOS, Al-or Ti isopropoxides, etc. in their respective parent alcohols and water as a reactant. In a first step, hydrolysis of the alkoxy groups results in M-OH species, which then condense to form amorphous metal oxide NBB or a sol. In view of the nature of the reversible interaction between the condensation of M-OH and the hydrolysis of the M-O-M bond, the material species obtained are difficult to control but strongly influenced by pH, precursor concentration and solvent system. The preparation of colloidal sols using hydrolysis is always a trade-off between avoiding gelation, achieving a high degree of branching and reducing the amount of volatile monomer fractions. Branched siloxane compounds with low molecular weight are obtained by acid-catalyzed hydrolysis in a neat system (without solvent), as described in EP 1510520 a 1.

The preparation of chemically modified colloidal sols with a controlled core-shell type architecture (e.g. TEOS based NBB with a shell made from a second functional silane) is complicated by the fact that: the hydrolysis and condensation kinetics of different silanes (TEOS versus the functional silane) can be widely different, resulting in poor surface selectivity of the deposition, as schematically shown in fig. 2. This is particularly true for co-hydrolysis of two different silane compounds, where there is a clear priority for forming a heterogeneous mixture of "silane a" and "silane B" particles, rather than phase-pure hybrid "AB" particles with a uniform, statistically mixed composition.

Slowing down the reaction kinetics is often the only option in order to improve the selectivity of deposition of the functional shell on NBB. EP 1978055 a1 describes the functionalization of commercial "Ludox" silica particles and similar colloids in dilute aqueous solutions by shells made of functional organosilanes by slowly dosing the functional silane and performing at pH 4 where the hydrolysis/condensation kinetics are very slow-allowing the reaction mixture to react at room temperature for a period of 24 h. A more rapid alternative is based on emulsion based radical polymerization chemistry: EP 1118632 a2 describes composite nanoparticles and their preparation, in which polymer core particles obtained by emulsion polymerization are coated with a layer of an organosilicon compound by means of suitable condensation chemistry. EP 3059262 a1 describes the reverse situation, namely a PDMS-like core prepared as an emulsion by coating with a polyacrylate shell made by free radical emulsion polymerization mediated using a silane coupling agent bearing acrylate functionality. Another very similar PDMS core/organic poly- (alkenyl aromatic) shell hybrid NBB material is described in US 2009/0215927.

Hyperbranched polyalkoxysiloxanes (hyPAS) are among the most promising candidates for achieving both functionality and size control in one and the same molecule in the world of silicon-based MBBs. The hyPAS are small molecule building blocks that typically range in size from a few angstroms to single digit nanometers spanning molecular weights in the range of 500 to 50'000 g/mol. In contrast to the "sol-gel" hydrolysis route described above, hyPAS are most often prepared by a "non-hydrolytic" process, meaning that: the condensation reaction for combining small molecule precursors to form larger macromolecular MBBs can be controlled by stoichiometric addition of reactants and can therefore be started, stopped, and resumed at any given point in time. Furthermore, the synthesis can be performed "neat", meaning that no additional solvent, such as water or alcohol, is present. The hyPAS exhibits lower melt viscosity and much greater solubility than its linear polymer analog due to its nearly spherical and compact nature. The preparative "non-hydrolytic" synthetic route for the classical single-component hyPAS is:

1) condensation of hydroxides obtained by reaction of alkoxysilanes with basic hydroxides (silanol route)

2) Condensation of chlorides with alkoxysilanes (chloride route)

3) Self-condensation of single alkoxysilanes with elimination by ether

4) Self-condensation of acetoxy-functional alkoxysilanes by elimination of the corresponding acetate (acetoxy route)

5) Condensation of alkoxysilanes by reaction with acetic anhydride via acetate elimination in the presence of a suitable catalyst (anhydride route).

Method 1) is quite impractical because it requires a quantitative amount of a highly caustic alkaline hydroxide and the recovery and disposal of the corresponding waste product.

Method 2) is described in EP 0728793A 1, wherein the preparation of hyperbranched polysiloxanes is carried out by heterogeneous condensation (heterocondensation) of chlorine and alkoxysilanes via elimination of alkyl halides. The reaction is catalyzed by organometallic compounds comprising Ti, V and Zr. Industrial commercialization is limited by the highly corrosive nature of chlorosilane reagents.

Process 3) suffers from large safety-related risks in industrial environments due to the formation of dialkyl ethers with very low boiling points and extreme flammability. Furthermore, the homogeneous condensation of such alkoxylates does not self-terminate with the consumption of a second, stoichiometric limiting species, such as chloro-, hydroxy-, or acetoxy-silane, and therefore would require imprecise knowledge of the reaction progress by thermal quenching stopping in time at any moment, making product control much more challenging.

Method 4) generally uses a rather expensive acetoxysilane. WO 00/40640 a1 describes the preparation of lightly branched organosilicon compounds by acetoxy derivatization starting from dimethylsiloxane prepolymers crosslinked with trifunctional silanes. The patent further describes the effectiveness of the classical acetoxy route when only a few condensation bonds need to be created, i.e. when linking monomers to oligomer/polymer building blocks to form larger macromolecules. This can be accomplished, for example, by refluxing the silanol-terminated prepolymer with alkoxy-terminated crosslinking agent in the presence of acetic acid at reflux at elevated temperature or directly with acetoxy-terminated crosslinking agent (e.g., triacetoxysilane).

Method 5) recently invented by Moeller et al (e.g. Macromolecules 2006, 39, 1701-. It offers vastly improved industrialization potential and state of the art closest to the present invention but at the same time does not address the "core-shell" like selective functionalization problem of the hyPAS over 1) to 4). Thus, WO 2004/058859a1 limited itself to the preparation of a single component, hyPAS MBB, via the anhydride route: in the examples, the authors discuss the preparation of pure silicate and titanate polyalkoxy metal salts from their respective alkoxides in a one-step process but mention is made exclusively of zirconates and hafnates in the critical claim 1, among other claims. This patent further describes in subsequent examples the analogous preparation of a single component organofunctional hyPAS prepared from organofunctional-trialkoxysilanes, specifically Methyltriethoxysilane (MTES) and heptadecafluoro- (1,1,2,2) -tetrahydrodecyltriethoxysilane. Organofunctional trialkoxysilanes are ideal precursors for the introduction of chemical functional groups due to their large selectivity and the attractive price of commercially available compounds. WO 2004/058859a1 does not exclude the preparation of statistically mixed multi-component hyPAS, which would be the most obvious way to introduce specific organic chemical functionalities, but does not specify this concept in further detail.

As an extension of the original work of Moeller, WO 2014/187972 a1 relates to the chemical functionalization of silicates hyPAS prepared by Moeller route 5) and their use as additives in coating formulations. The functional precursor is produced by alcohol condensation of a hydroxyl-terminated polymer with accessible alkoxy groups on the "Moeller-type" hyPAS, preferred examples being polyalkylene ethers such as PEG, PPG and Polydimethylsiloxane (PDMS) at a temperature range of 130 ℃. In this way, core-shell MBBs modified with PEG, PPG, PDMS, etc. are produced, but still do not have the full freedom to prepare the shell in a bottom-up manner with complete control over the composition and shell substructure. The main difference from the present invention is the shell grafting pattern of the single chemical bond formed by the attachment of the preformed linear polymer molecules to the hyPAS core.

Disclosure of Invention

It is an object of the present invention to provide improved hyPAS materials, methods of making the same, and various applications thereof.

According to one aspect of the present invention (claim 1), there is provided a method of preparing a polymeric liquid material formed of molecular building blocks of core-shell type construction, each building block consisting of a hyperbranched polysiloxane core and a functional siloxane shell peripherally attached to said core, said method comprising the steps of:

a) at least one tetraalkoxysilicon Si (OR)₄And optionally in monomeric or oligomeric form withDP of (1)_CoreA first stoichiometric amount of acetic anhydride is selected to be added together in the presence of a catalyst to the reaction vessel, wherein R is an unbranched or branched alkyl group having up to four carbon atoms:

an R '-organofunctional trialkoxysilane R' -Si (OR)₃And optionally R₃,R₄-organofunctional dialkoxysilanes R₃-Si(OR)₂-R₄(ii) a Or

-a mixture of different R' -organofunctional trialkoxysilanes and optionally at least one R₃,R₄-organofunctional dialkoxysilanes;

b) heating the reaction mixture provided in step a) in an anhydrous inert atmosphere with stirring until the desired reaction temperature is reached and distilling off the resulting acetate reaction products until the reaction and the flow of distillate cease, thereby forming the hyperbranched polysiloxane core;

c) the following are mixed with DP according to desire_ShellA second stoichiometric amount of acetic anhydride selected is added together, optionally in the presence of a catalyst, with constant stirring, to the hot reaction mixture formed in step b) to initiate the selective accumulation of the functional siloxane shell on the core produced in step b), wherein additional acetate is formed and distilled off, and the reaction is continued until distillate flow is once again stopped:

an R '-organofunctional trialkoxysilane R' -Si (OR)₃And optionally R₁,R₂-organofunctional dialkoxysilanes R₁-Si(OR)₂-R₂Or is or

-a mixture of different R' -organofunctional trialkoxysilanes and optionally at least one R₁,R₂-an organofunctional dialkoxysilane,

wherein:

r 'and R' are independently selected substituents each of which can be represented by L-Z, wherein

L is selected from-C₆H₄-、-C₆H₄-CH₂-、-CH₂-CH₂-C₆H₄-CH₂-and- [ (CH)₂]_n-wherein n ═ 0, 1,2, 3, 4; and

-Z is a terminal functional group selected from:

wherein R is selected from-H, -CH₃、-C₂H₅、-C₃H₈、-C₄H₁₀and-C₆H₅；

Or Z is- [ (CH)₂]_m-CH₃Wherein m is 0, 1,2, … …, 11; and

-wherein R is₁、R₂、R₃And R₄Is independently selected from-CH₃、-C₂H₅、-C₆H₅、-C₆H₁₁、-CH＝CH₂、-CH₂-CH₂-Cl and C₅H₅The substituent(s) of (a),

provided that (R', R) of the triplet₁、R₂) And (R', R)₃、R₄) Are not identical;

d) optionally, building an additional functional layer in the shell by repeating the addition and reaction scheme described in step c) at least once;

e) optionally, removing low molecular reaction products and/or residual starting materials in the reaction mixture by vacuum distillation via gradually reducing the pressure inside the reaction vessel and maintaining the final pressure in the range of 5 to 250 mbar for a period of 10-120 minutes;

f) cooling and separating the polymeric liquid material thus obtained;

wherein steps a) to e) are carried out in the same reaction vessel.

As will become more apparent below, the core may include a limited amount of organofunctional siloxane moieties in addition to the primary non-organofunctional siloxane component. The shell is by definition composed of organofunctional siloxane moieties only. IIIOne group of (R', R)₁、R₂) And (R', R)₃、R₄) The condition of being non-identical means that the shell composition and optionally the composition of the functional group-bearing core component are not identical.

In the above preparation method, the amount of reactants used in the various steps will be selected according to the desired composition of the polymeric liquid material to be formed. Specifically, the amount of reactants will be selected to meet the content limits as further defined below.

In the present context, the term "functional pre-mixture" shall be used to refer to the amount of at least one organofunctional trialkoxysilane and optionally a dialkoxysilane added in step a). By such a premix, certain functional properties can be imparted to the core.

Advantageous embodiments are defined in the dependent claims and in the following description and examples.

According to one embodiment (claim 2), the functional premix is zero. That is, the core is substantially exclusively composed of non-organofunctional siloxane moieties.

According to a further embodiment (claim 3), R is methyl or ethyl.

According to another embodiment (claim 4), the reaction temperature of steps b) to e) is in the range of 70 ℃ to 170 ℃, preferably in the range of 100 ℃ to 150 ℃, and most preferably in the range of 120 ℃ to 140 ℃ and the pressure during steps b) to d) is in the range of 0.1 bar to 2 bar, preferably in the range of 0.5 bar to 1.4 bar, and most preferably in the range of 0.9 bar to 1.2 bar.

According to still another embodiment (claim 5), the tetraalkoxysilicon Si (OR)₄Tetraethoxysilane (TEOS) or Tetramethoxysilane (TMOS) or mixtures of monomers and oligomers thereof.

According to a further embodiment (claim 6), the acetate reaction product is removed from the system by passing it through a distillation column comprising a plurality of theoretical plates in such a way that: the lower boiling reaction product in solution is separated from the higher boiling residual reactant, whereby the latter is continuously fed back into the reaction mixture.

According to an even further embodiment (claim 7), the catalyst is selected from Ti (OR ")₄OR Zn (II) alkoxide Zn (OR')₂Wherein R ═ CH₂CH₃、-CH(CH₃)₂、-CH₂CH₂CH₃、-C(CH₃)₃、-CH₂CH₂CH₂CH₃Or the catalyst is Ti (O-Si (CH)₃)₃)₄Wherein the amount of catalyst is between 0.01 and 1.5% based on moles of total alkoxysilane precursor used in the step of growing the core.

According to a further embodiment (claim 8), R' is selected from the following groups:

i)R'＝-C₆H₅、-CH＝CH₂，

ii) R' ═ L-Z, and L is-CH₂-and Z ═ CH- [ (CH)₂]_p-CH₃Wherein p is 0, 1,2, 4, 6, 8, 10, 12, 14,

iii) R' is L-Z, and L is-CH₂CH₂CH₂- (n-propyl) and Z ═ Br, -Cl, -I, -SH, -OH, -NH₂NH- (BOC), -NH- (FMOC), -2-oxetanyl, -methoxy- (2-oxetanyl), -N₃、-SO₃R、-PO₃R₂-acrylate, -methacrylate, -ethacrylate, -propylacrylate, -butylacrylate, or

iv) R ═ L-Z, and L ═ CH₂Z is vinyl, acrylate, methacrylate, ethacrylate, propylacrylate, butylacrylate,

wherein R is₁And R₂Are identical and are selected from the group consisting of-CH₃、-C₆H₅and-CH ═ CH₂Or wherein R is₁＝-CH₃And R is₂＝-CH＝CH₂。

According to a further aspect (claim 9), there is provided a polymeric liquid material prepared by the process of the present invention carried out in the absence of a functional pre-mixture. The material is formed of molecular building blocks of core-shell type construction, each block consisting of a hyperbranched polysiloxane core and a functional siloxane shell peripherally attached to said core,

the material comprises less than 0.5 mass percent of hydroxyl moieties (Si-OH),

the core has a degree of polymerization DP in the range of 1.3 to 2.7, in particular 1.5 to 2.5_Core，

The shell is formed of an R' -substituted siloxane moiety and an optional R1-, R2-substituted siloxane moiety and has a degree of polymerization DP in the range of 0.3 to 2.5, specifically 1.0 to 2.3_Shell，

Wherein the molar ratio of total silicon to hydrolysable free alkoxy groups in the material is 1:1.25 to 1:2.75,

wherein the material has a viscosity in the range of 10 to 100'000cP,

and wherein the core is comprised of non-organofunctional siloxane moieties comprising

-a non-organofunctional end-bonded siloxane moiety of the formula (Q)¹Species)

And/or

-a non-organofunctional disiloxane moiety (Q) of the formula²Species)

And/or

-a non-organofunctional trisiloxane moiety of the formula (Q)³Species)

And/or

-a non-organofunctional tetrasiloxane moiety of the formula (Q)⁴Species)

And wherein the shell is comprised of:

-a mono-organofunctional end-bonded siloxane moiety (T) of the formula¹Species)

And/or

A mono-organofunctional disiloxane moiety (T) of the formula²Species)

And/or

A mono-organofunctional trisiloxane (T) of the formula³Species) moiety

And optionally

-a terminally bonded diorganofunctional siloxane of the formula (D)¹Species) moiety

And/or

A diorganofunctional disiloxane of the formula (D)²Species) moiety

Wherein R, R' and R₁And R₂As defined in claim 1.

According to one embodiment, the material has a viscosity ranging from 50 to 5'000 cP.

Advantageously (claim 10), the relative atomic ratio of species T to Q ranges from 0.03:1 to 1:1. preferably 0.03:1 to 0.75: 1. and most preferably 0.05:1 to 0.5: 1.

according to another aspect of the present invention (claim 11), there is provided a hydrolysate obtainable by reacting the polymeric liquid material according to the first aspect with a predetermined amount of water or a predetermined amount of a water-solvent mixture.

According to a further aspect, the polymeric liquid material according to the further aspect or the corresponding hydrolysate according to the second aspect is used for a plurality of applications as defined in claims 12 and 13.

It has surprisingly been found that the acetic anhydride reaction (i.e. process 5 mentioned in the introduction)) can be used in a sequential manner to selectively accumulate a functional shell on an existing hyPAS core or core by feeding a single compound or mixture of organofunctional silanes comprising at least one organofunctional trialkoxysilane under the same reaction conditions.

Direct reaction product

Apparently macromolecular in nature, with the typical size of the core-shell MBB for its constituents being below 2 nm;

-exhibits a statistical distribution of molecular weights, the content of unreacted monomers and small oligomers varying depending on the chosen reaction conditions; the low molecular species may optionally be removed by vacuum distillation and reused. The individual components typically contain 30 to 500 Si atoms;

-a substantial amount of hydrolysable reactive cross-linking alkoxy groups in both the core and the shell;

-is a neat MBB liquid mixture substantially free of solvent, with a viscosity in the range of 10-100'000 cP;

in terms of the molecular structure of MBB, it is star polymer-like.

A clear distinction from other star polymers known from the prior art can be the hyperbranched nature of the core, which indicates a considerable degree of crosslinking in the core and more importantly the nature of the shell in terms of its variable size (from end-capping to predominantly linear polymer chains of variable length). The relevant formulation in practice falls on the core (DP)_Core1.3-2.7) and shell (DP)_Shell＝0.3–2.5) Both substructures have a limited polymerization range.

For the purposes of the present invention, the term "core-shell" has been adopted from nanomaterial science. Based on the apparently macromolecular character of the reaction products covered by the present invention, the interface between core and shell must be understood as a diffusive shell rather than a sharp boundary where the composition changes abruptly. The diffusion shell configuration is a direct result of condensation chemistry (i.e., grafting a functional silane shell onto a preformed hyPAS core), in which the concentration of functional shell species varies over a few bond lengths or angstroms. Since the outer arm of the dendritic hyPAS core is highly permeable to smaller silane monomers and oligomers, the following is evident: the degree of grafting of the shell is highest peripherally but there are no sharp interruptions. Nevertheless, the term "core-shell" still applies, since grafting at the core center is highly hindered both for steric reasons and for the reduced availability of reactive alkoxy groups, since the average degree of connectivity (number of bridging oxygen linkages (Si-O-Si linkages) per silicon center) is higher at the core center than at the core periphery. As a result, the term "core-shell" will be used in the context of the present invention in the meaning of a hyPAS core with a diffusion shell, according to the above demonstration.

The degree of polymerization DP of any amorphous silicon oxide material can be defined as the total number of metal atoms Si bridged with oxygen BO (a # -Si-O-Si bond) in the system_{General assembly}The ratio of (a) to (b).

For the degree of polymerization:

-DP ═ 4, all Si atoms are bonded to four other vicinal atoms (neighbors), i.e. this is the case in perfect crystals (quartz) where four oxygen atoms are located at the tetrahedral sites of each central Si and each Si atom appears to be the exact same environment

-DP ═ 3, on average, each Si atom is bonded to three other Si atoms (Si-O-Si) via bridging oxygen linkages. If an individual component has a DP of 3, its structure will be an infinitely extended two-dimensional sheet, similar to a sheet-like clay mineral.

-DP ═ 2, on average, each Si atom being bonded via two bridging oxygen bonds. The single component analog will be a linear polymer such as an uncrosslinked PDMS (polydimethylsiloxane) type silicone resin.

The acetic anhydride reaction is quantitative in terms of its reagents (alkoxylate and acetic anhydride). The number of new bonds formed as a result of their addition and also the DP is therefore proportional to the conversion factors f and g of the stoichiometry of the accumulation reaction of the core i) and shell ii) shown below:

i)

formed from the core of the tetraalkoxide model compound (equation i)), the maximum stoichiometric factor f ═ 2 corresponds to 2: 1 acetic anhydride to tetraalkoxide ratio, which leads to a practically impossible DP of 4, i.e. complete conversion to SiO₂。

Mechanistically, the acetic anhydride reaction proceeds via the acetoxy intermediate by eliminating the first aliquot of acetate, as in equation i_a) As shown therein. The acetoxy intermediate is then subjected to intramolecular condensation with the alkoxy group on the second molecule, with elimination of the second aliquot of acetate, as in equation i_b) As shown therein.

i_a)

i_b)

Such as inAs already described in the original work, organofunctional trialkoxysilanes can also be converted to hypAS using anhydride chemistry according to equation ii),

ii)although lower DP results from a lower number of alkoxy groups available for the condensation reaction (3 instead of 4)_Core. Mechanistically, di-and trialkoxysilanes react in the same manner as tetraalkoxysilanes.

Most glasses and hyPAS are characterized by average values of DP significantly below their theoretical limit (complete conversion of all alkoxy groups). During preparation, the theoretical value of DP is given by the stoichiometric ratio used in the reaction and the effective value of DP can be determined directly by quantitative analysis of the acetate reaction product. Independently, DP of said material_CoreAnd DP_ShellCan be obtained directly from quantitative NMR data. In the case of a simple model for obtaining a single-component hyPAS from tetraalkoxysilane, DP can be quantified as follows²⁹Si NMR spectrum (fig. 3) calculation:

DP＝∑(n A_Qn)/∑(A_Qn)＝(A_Q1+2A_Q2+3A_Q3+4A_Q4)/(A_Q0+A_Q1+A_Q2+A_Q3+A_Q4)

wherein A is_QnRepresents and the QⁿSpecies related quantification²⁹Area of Si NMR peak, said QⁿThe species is a Si atom coordinated by n Bridging Oxygen (BO) atoms connecting it to the next nearest neighbor Si neighbor atom through a Si-O-Si bridge and 4-n non-bridging oxygen (NBO) atoms (i.e., alkoxy groups Si-OR).

In the case of a pure tetraalkoxysilane model system and assuming quantitative conversion, DP is positively correlated with the stoichiometric f-factor (equation i) by the following simple relationship:

DP＝2f。

in the case of the organofunctional di-and trialkoxysilanes,²⁹the Si spectral fingerprint region gradually migrates further to a lower magnetic field, allowing for multiple non-organic functional QⁿWith organofunctional T^mAnd D^lThe apparent separation of chemical groups as seen in the pattern of the model compound after shell deposition (fig. 4). Here, A_TmRepresents the peak area under the curve and A for each Si species belonging to the organofunctional trialkoxysilane with m BOs and (3-m) NBOs_DlIs a peak surface derived from an organofunctional dialkoxysilane having l BOs and (2-l) NBOsAnd (4) accumulating.

However, the determination of the degree of condensation and polymerization of the core-shell molecules is more complicated. Degree of Polymerization (DP) of core prior to addition of shell precursor and additional acetic anhydride_{Core, initial}) Follow the equation of a pure system and can be quantified²⁹Si NMR (fig. 3) or by the following stoichiometry:

DP_{core, initial}＝∑(n A_Qn)/∑(A_Qn)＝(A_Q1+2A_Q2+3A_Q3+4A_Q4)/(A_Q0+A_Q1+A_Q2+A_Q3+A_Q4)，

DP_{Core, initial}＝2f

Wherein A is_QnQuantification of aliquots taken prior to addition of the shell precursor²⁹Si NMR spectrum was deduced.

For MBB materials according to the invention characterized by a shell grown from an organofunctional trialkoxysilane on an existing tetraalkoxysilane core, the addition of new monomers and acetic anhydride results in the following reaction, where g is defined as the molar ratio of acetic anhydride to organofunctional trialkoxysilane.

i) Continuation of the core polymerization (Q-Q condensation),

ii) homogeneous condensation of T species (T-T condensation), and

iii) grafting of functional silanes onto existing core siloxane branches (T-Q condensation).

The homogeneous condensation reaction (T-T) can only bring about the Degree of Polymerization (DP) of the shell_Shell) Increasing, but according to the exemplary grafting reaction iii) given below, heterogeneous condensation (T-Q) of DP_CoreAnd DP_ShellBoth increase:

iii)

note that in the above example of the grafting reaction, R' is organofunctional with a trialkoxysilane consisting of T⁰Conversion to T¹While the core species on the left-hand side of the reaction (symbolized by three wavy siloxane bonds) is represented by Q³Conversion to Q⁴The respective grafting reaction is describedDP_CoreAnd DP_ShellWhile increasing. It is clear that there is a wide variety of possible grafting reactions (e.g.T)²Species grafted to Q²To respectively generate T³And Q³Or T¹Species grafted to Q²To produce T²And Q³Etc.).

The experimental results suggest that T-Q condensation (grafting) is the preferred reaction within the limitations described in the present invention. As can be seen from the view of figure 5,²⁹Si-²⁹the Si INADEQUATE NMR spectrum showed clear signals related to Q-Q and Q-T correlations, but the peaks related to T-T homogeneous condensation were below the detection limit, demonstrating that the grafting of trifunctional silanes onto the pre-assembled core is the dominant T condensation mechanism, rather than the T-T condensation and/or the formation of a pure phase condensate species made from organofunctional trialkoxysilane building blocks.

The final degree of polymerization of the core-shell macromolecule can be quantified after completion of the reaction with the shell precursor according to the following²⁹Si NMR spectrum determination:

DP_{core, finally}＝∑(n A_Qn)/∑(A_Qn)＝(A_Q1+2A_Q2+3A_Q3+4A_Q4)/(A_Q0+A_Q1+A_Q2+A_Q3+A_Q4)

DP_Shell＝∑(m A_Tm)/∑(A_Tm)＝(A_T1+2A_T2+3A_T3)/(A_T0+A_T1+A_T2+A_T3)

DP_{All are}＝[∑(n A_Qn)+∑(m A_Tm)]/[∑(A_Qn)+∑(A_Tm)]

Wherein A is_QnAnd A_TmFrom the quantity collected after completion of the reaction with the shell precursor²⁹Si NMR spectrum (fig. 4).

DP due to the aforementioned reactions i) to iii)_{Core, finally}And DP_ShellCannot be formed from f, g and n_Shell/n_CoreRather than direct calculation, since the relative importance/selectivity of the T-T and T-Q reactions is not known a priori and will depend on QⁿAnd T^mMonomeric and higher molecular hyPAS core speciesRelative reactivity of (a). Nevertheless, f, g and n are expressed by the following equations_Shell/n_CoreAssociated to the respective degree of polymerization:

DP_{general assembly}＝2[n_Core/(n_Core+n_Shell)]·f+2[n_Shell/(n_Core+n_Shell)]·g

2g＝(n_Core/n_Shell)·ΔDP_Core+DP_Shell

Wherein Δ DP_Core＝DP_{Core, finally}–DP_{Core, initial}E.g. from the quantification collected after (FIG. 4) and before (FIG. 3) addition of trifunctional monomer and acetic anhydride²⁹Si NMR spectrum.

The MBB according to the invention consists of a core of hyPAS based on tetraalkoxysilane. Selection of f-factor during core assembly determines DP_{Core, initial}(not and DP_{Core, finally}Same required design parameter DP_CoreConfusion) and also the size, molecular weight and degree of branching of the resulting core prior to shell growth. The shell consists of a single polysiloxane layer made from an organofunctional trialkoxysilane monomer or mixture grown in a second (and possibly in additional subshells) in a subsequent temporally separate step (a). Optionally, the shell monomer mixture comprises a minority of organofunctional dialkoxysilane.

The desired amount of acetic anhydride (g-factor) added during shell growth determines its size (polymer average chain length) and species. Higher g-factors (g ═ 0.75 to 1.25) produce chain-like, slightly branched organodisiloxane shells, while lower g-factors (g ═ 0.15 to 0.5) favor end-capping of the core by organofunctional monomers and short oligomers. On the other hand, a low g-factor conversion is always accompanied by a relatively high content of unreacted monomers (T) in the reaction mixture₀Species) which may be undesirable for practical use but which can be removed by distillation as desired.

The MBBs covered by the present invention span a wide range of configurations in terms of the amount of material making up the core and shell, as illustrated in the specific example given in fig. 6. This range of control over shell functionality may be best accomplishedMolar ratio of precursor monomers used to construct the shell and core (n)_Shell/n_Core) A discussion is made. Generally, lower n_Shell/n_Core<The 0.2 ratio yields the following materials: it is considered to be a functional dendrimer and its surface chemistry is dominated by the core composition, whereas the higher n_Shell/n_CoreRatio of>0.5 produced a material: it is apparently star-shaped polymer-like in nature and its surface chemistry is dominated by the shell composition. At n_Shell/n_CoreIn the intermediate compositional range between 0.2 and 0.5, the surface chemistry and reactivity are determined by both (core and shell compounds). For any given n_Shell/n_CoreThe bonding pattern of the shell species can be controlled by the amount of acetic anhydride (g-factor) added during the shell growth step, which directly affects the yield of the shell in the cell²⁹Population of species observed in Si NMR spectra.

For DP_{All are}>2.0 unreacted monomer species (defined as Q for the corresponding tetra-, tri-and di-alkoxysilanes) in the crude MBB reaction mixture according to the invention⁰、T⁰、D⁰) Less than 10% by weight, preferably less than 5% by weight, and most preferably less than 2% by weight. The amount of unreacted monomer species after the core and before the shell growth step can be further reduced by distilling off residual monomer. The amount of unreacted monomer species in the NBB hydrolysate according to the invention is less than 1 wt%.

In an advantageous embodiment, the core is derived from tetraalkoxysilane (preferably TEOS or TMOS) or its low molecular industrial oligomers such as Dynasilan 40(Evonik industries) or equivalent, and the shell is derived from a one-component monomeric organofunctional trialkoxysilane or a multicomponent trialkoxysilane mixture, respectively.

In a further advantageous embodiment, the core is derived from tetraalkoxysilane (preferably TEOS or TMOS) or its low molecular industrial oligomers such as Dynasilan 40(Evonik industries) or equivalent, and the mono-component shell is composed of a mixture of monomeric organofunctional trialkoxysilane and dialkoxysilane. By replacing the organofunctional trialkoxysilane by a dialkoxysilane, the content of hydrolyzable reactive crosslinker groups Si-OR can be precisely controlled. In this way, MBBs with properties similar to more hydrophobic polydimethylsiloxanes (PDMS, silicones) and reduced sensitivity to water can be obtained, with the exact properties adjusted to the specific needs of the application.

In another advantageous embodiment, the shell is prepared to consist of more than one layer of a plurality of organofunctional trialkoxysilanes and also optionally dialkoxysilanes. Just as in order to selectively grow the shell on top of the core by temporally separating the core and shell assembly, additional layers of organofunctional siloxane may be grown by repeating the shell growth procedure once or several times. In a particularly preferred embodiment, the first shell carries an organic functional group selected from methyl, vinyl, etc., which serves the primary purpose of controlling the hydrophobic and hydrolytic/condensation properties of the resulting MBB material, and the outermost shell layer carries a specific functional group selected to aid reactive crosslinking, polymerization, and interfacial compatibility with the application-related matrix, such as a thiol, (BOC or FMOC protected) amine, vinyl, acrylate, phosphonic acid, or sulfonate ester, etc.

In a further advantageous embodiment, the core is prepared to also comprise a minor component (less than 25% on a molar basis) bearing selected chemical functional groups capable of, for example, increasing the adsorption/doping of guest species such as metals and transition metal ions or small molecule drugs, etc., in order to control and preferably tailor the functional groups. Particularly suitable for this purpose are tetraalkoxysilanes, preferably TEOS (tetraethoxysilane) or TMOS (tetramethoxysilane) or oligomers thereof, and compounds which carry specific ligand groups (-NH)₂、SH、-PO₃H) Or covalently bonded positively or negatively charged species (-SO 3)^-、-PO₃ ^-2、COO^-、-NR₃ ⁺) A core of a mixture of organofunctional trialkoxysilanes. The ligand group bearing a functional group is preferably formed by reacting a primary tetraalkoxide component with a protected functional group monomer precursor (e.g., -NH-BOC or-NH-FMOC, -NH (butylene), -SO) through the core₃R、-PO₃R₂Blocked trialkoxysilane) are co-assembled together.

One of the main advantages of the new class of MBBs covered by the present invention lies in the fact that: these materials are essentially free of hydroxyl species (< 0.5% Si-OH mass content), which means that they provide greatly improved stability and shelf life and substantially more structural control over conventional sol-gel based hybrid materials. In practical applications, MBB can be used "as is" in non-polar organic solvents, blends, etc. or doped directly into a hydrophobic matrix such as a polymer melt.

The relative amounts of core and shell materials may vary over a considerable range. According to an advantageous embodiment, the shell-to-core molar ratio n_Shell：n_CoreFrom 0.05 to 2.0, preferably from 0.1 to 1.0.

According to a further embodiment, the relative atomic content of T species in the shell is at least 10%, and preferably at least 20%.

According to one aspect, the MBB product is converted to nanoscale components by hydrolysis directly in water or in a suitable water/solvent system, as desired, in the presence of an acid or base catalyst. The hydrolysate according to the invention is a Nanoscale Building Block (NBB) but has a perfectly controllable molecular substructure and customizable functionalities, as schematically shown in fig. 7. Compared to the state of the art, such novel hydrolysate NBB has the following advantages: improved composition control and more efficient use of shell components (tri-and dialkoxysilanes with functional groups) which are generally cost-prohibitive components in practical applications.

Further, an advantageous method for the preparation of MBB is outlined. The hyPAS core is first prepared according to a core build reaction i), that is, a tetraalkoxysilane, such as TEOS or TMOS, is combined with a selected substoichiometric amount f of acetic anhydride in the presence of a catalyst and the mixture is heated to a typical reaction temperature in the range of 120-140 ℃. Mechanistically, acetic anhydride first reacts with free alkoxy groups in a rate limiting step to form acetoxy intermediates (equation i)_a) And a first molecule of an acetate reaction byproduct. In the second step (equation i)_b) In (3), the acetoxy intermediate is then reacted with a monomer, oligomer or an already present hyPAS moleculeThe second alkoxy group on to form a second molecule of M-O-M (in this case Si-O-Si) bonds and acetate by-products. Initially, the starting materials (tetraalkoxide and acetic anhydride) were high, which means that the kinetic rate was high and acetate rapidly accumulated in the reaction mixture. Thus, boil-over (boil over) of acetate by-product formation can occur after the reaction begins, the acetate by-product having a significantly lower boiling point than both the starting material and the hyPAS primary reaction product. As the reaction proceeds, the average size, molecular mass, and thus DP of the hyPAS core with more and more siloxane bonds formed_{Core, initial}And is increased. At higher f-factors, NMR speciation is also directed to higher QⁿAnd (4) evolution. Acetic anhydride is used in substoichiometric amounts in the starting mixture, so that it will be exhausted at some point and the reaction will spontaneously terminate. Again, since the reaction is completely stoichiometric with respect to the starting materials, the progress of the reaction or more technically the degree of polymerization DP_{Core, initial}Proportional to f-factor and DP_ShellAnd DP_CoreThe statistically weighted sum is proportional to the g-factor. This means that the core and shell growth are separated in time and can be controlled independently of each other.

Once the core assembly is complete and the distilling off of the acetate has ceased, the core is end-capped with and/or grown on an organofunctional siloxane shell by at least one addition, but optionally also a subsequent controlled addition of a plurality of times, of an organofunctional trialkoxysilane compound or mixture and also optionally an organofunctional dialkoxysilane or mixture, together with a selected substoichiometric amount (g-factor) of acetic anhydride required for the shell polymerization, under continuous stirring at temperature to this same reaction mixture. Distillation of additional acetate reaction by-products is resumed during or shortly after the addition. It is noted that organofunctional trialkoxy-and dialkoxysilanes contain only three and two alkoxy groups available for the acetic anhydride reaction and therefore the effective g-factor needs to be adjusted to a given specific shell or sub-shell mixture. The ratio of substoichiometric acetic anhydride to total shell silane monomer is determinedDefined as g-factor and typically selected such that DP_ShellAnd is kept in the range of 0.3-2.5. According to the invention, the molar fraction of T-species in the shell based on trialkoxysilane must be at least 5%, 10% and preferably at least 20%.

In a further advantageous embodiment, the multi-component shell construction is deposited by repeating the shell addition procedure multiple times with a plurality of organofunctional trialkoxysilane and optionally dialkoxysilane monomers. Each monomer is preferably added with its selected equivalent amount of acetic anhydride, which is required to produce the desired degree of condensation of the sub-shell of interest.

As known from the original published work on hyPAS reported by Moeller et al (Macromolecules 2006, 39, 1701-1708), the degree of polymerization/f-factor of single-component tetraalkoxysilane compounds is limited to values of about 2.5/1.25, respectively. The explanation lies in the fact that: the pure hyPAS core remained growing with more and more M-O-M bonds formed due to the increase in DP/f. At some point we will reach a point where most of the low-molecular species have reacted away and since then the dendritic arms of the hyPAS will join together through additional condensation reactions. This explains why the viscosity of such compounds increases considerably at DP/f values above 2.2/1.1, respectively, and also translates into a considerable range of available liquid material viscosities. For the single precursor TEOS hyPAS model compound prepared using the Moeller method, an f-factor above 1.3 will result in a solid three-dimensional cross-linked product that is no longer soluble. The core-shell MBBs according to the invention are also limited in size, with the sum of the common limits and the f and g factors (DP)_{General assembly}) Are directly related. Following the same logic as the Moeller original model system, grafting a trifunctional organofunctional trialkoxysilane onto the hyPAS core by additional acetic anhydride resulted in MBB growth. Grafting and upconversion of echelon T with an increase in g-factor when organofunctional trialkoxysilane monomer⁰->T¹->T²->T³The same situation as the pure hyPAS component will occur, that is, most of the monomer and small molecule species have reacted away and become statistically more prevalent as followsIt is possible to: the new bond formed connects the two arms through the residual alkoxy groups. In experimental studies, once the core of a given f-factor is further converted to core-shell MBB and the g-factor steadily increases, a sharp increase in the viscosity is observed, eventually leading to the formation of a fully three-dimensionally crosslinked rubber or gel-like material.

Characterization of the reaction products with respect to viscosity is carried out by means of standardized viscosity measuring devices, such as cylindrical rotational viscometers, according to, for example, ASTM E2975-15: "Standard Test Method for Calibration of centralized Cylinder rotation scales" was easily analyzed. Other viscosity measurement methods are also possible, such as a Staudinger type capillary viscometer or a modern kinetic viscosity analysis method.

Characterization of the reaction product with respect to molecular precursors and DP of both the core and shell is simplest for a one-component core/one-component shell material, where the species formation of the core and shell is from a quantitative solution²⁹Si NMR measurement devices were easily analyzed. For more complex compositions, in general,²⁹si NMR still allows significant separation of the organofunctional components of the core and shell as long as the specific spectrum of the organofunctional group shifts. A specific chemical assay protocol for the general case (with optional functional pre-mix according to claim 1) comprises preparing a core as defined in claim 1, aspirating an aliquot, and subjecting it to a permissive determination of DP_Core，_InitialIs/are as follows²⁹Si-NMR analysis, followed by one or more shell growth steps, and again by²⁹Si-NMR analysis of the final material to give DP_{Core, finally}And DP_Shell。

For the specific case where the premix of the functional silane component in the core growth step is zero (claim 2) and the material claims dependent thereon (claim 9), the mono-component of the final material²⁹Si NMR spectrum sufficient for DP_CoreAnd DP_ShellIt is characterized in that the relative amounts can be directly deduced from the characteristics of the Q-and T, D-form NMR spectra, respectively.

One of the key aspects of the present invention is the grafting of the shell monomer onto the preformed core. Relating to TEOS-core/MTES (methyl-triethoxysilane)) 2D INADEQUATE of Shell model Compounds²⁹Si-²⁹Si NMR studies have revealed that₂/T₂、Q₂/T₁Strong cross peaks in between, which is strong evidence for direct grafting of functional T species onto the Q core. More importantly, high selectivity is predicted due to the absence of T-T cross peaks in the 2D NMR spectra. Surprisingly, the rate of dosing of the shell monomer does not significantly alter the product distribution, as would be expected by analogy with seeded-growing core-shell nanoparticles. This is supported by the following observations: the rate of the shell assembly reaction, as measured by the distillation rate of the acetate reaction product, was found to be completely independent of the trifunctional silane addition rate.

The use of elevated temperatures in combination with catalysts is required for non-hydrolyzed acetic anhydride chemistry in order to allow for sufficiently fast kinetics to produce reasonable reaction times. The reaction temperature of steps b) to e) is in the range of 70 ℃ to 170 ℃, preferably in the range of 100 ℃ to 150 ℃, and most preferably in the range of 120 ℃ to 140 ℃. The pressure during steps b) to d) is in the range of 0.1 to 2 bar, preferably in the range of 0.5 to 1.4 bar, and most preferably between 0.9 and 1.2 bar.

Depending on the reaction temperature, some of the monomers and acetic anhydride reagents are close to their boiling points. Each reaction step (core and shell/subshell formation) typically takes between half an hour and several hours depending on the type and concentration of catalyst used, some of the reagent tends to distill off with the acetate by-product. This leads to a gradual loss of the selected reagents depending on their boiling point and thus to an f/g efficiency factor lower or higher than that expected from the stoichiometry analysis used and also to a DP value. These losses can be quantified as the difference between the molar amount of acetic anhydride used (f, g factor) and the bond effectively formed (NMR analysis, quantification of acetate reaction product).

In an advantageous embodiment (claim 6), the loss of monomer and/or acetic anhydride reagent during the entire reaction is counteracted by: the reactor was equipped with a distillation attachment containing a separation stage with multiple theoretical plates connected to a distillation bridge, allowing quantitative separation of low boiling acetate reaction byproducts from unused high boiling volatile reagents, which were fed directly back to the reactor. This greatly improves both the accuracy (DP effective value is consistent with the selected amount of reagent used) and the reproducibility (the derivation of the theoretical value relative to f, g effective factor depends on the starting monomer & reaction temperature, etc.) of the manufacturing process.

Such asThe catalysts reported in their original patent applications for the non-hydrolysis process of acetic anhydride are advantageously selected from the family of tetraalkoxy titanates Ti (OR)₄Or zinc diethanolate Zn (OR)₂Wherein R is-CH₂CH₃、-CH(CH₃)₂、-CH₂CH₂CH₃、-C(CH₃)₃or-CH₂CH₂CH₂CH₃. More recent studies have identified titanium tetrakis (trimethylsiloxy) Ti (O-Si (CH) as a particularly suitable catalyst₃)₃)₄. The catalyst concentration is typically in the range of 0.02% mol to 1.5% mol, based on the total molar amount of silicon alkoxide used in MBB production. The catalyst is typically added in the core build step and the injection of additional catalyst during the shell growth step is optional but generally not necessary.

Advantageously (claim 7), the catalyst is chosen from Ti (OR ")₄OR Zn (II) alkoxide Zn (OR')₂Wherein R ═ CH₂CH₃、-CH(CH₃)₂、-CH₂CH₂CH₃、-C(CH₃)₃、-CH₂CH₂CH₂CH₃Or the catalyst is Ti (O-Si (CH)₃)₃)₄And the amount of catalyst is between 0.01 and 1.5% based on moles of total alkoxysilane precursor used in the step of growing the core.

In summary, the invention solves the following tasks: the selective shell growth of organofunctional trialkoxysilanes, optionally also containing organofunctional dialkoxysilanes, onto the hyPAS "core" by temporally separated reactions results in a new set of functional Molecular Building Blocks (MBBs) with extreme variability in terms of composition, architecture and properties within a limited stoichiometric window of core/shell compounds. Further, the MBB-derived hydrolysates covered by the present invention provide a new way to prepare nanoscale components (NBBs) with great precision and control over their sub-nanostructure and composition. The corresponding process for the manufacture of core-shell MBBs comprises a two-or multi-step reaction wherein a mixture comprising at least an organofunctional trialkoxysilane and optionally an organofunctional dialkoxysilane is selectively deposited using the same acetic anhydride reaction, temporally after the preparation of a core derived from a tetraalkoxysilane or oligomer selected therefrom by a non-hydrolytic acetic anhydride process. The temporally separated shell deposition can be repeated multiple times, allowing the assembly of complex multi-layer shell constructions.

Drawings

The above-mentioned and other features and objects of this invention and the manner of attaining them will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1 molecular and nanoscience constitute a general classification of atomic numbers and effective sizes;

FIG. 2 limitations of classical sol-gel hydrolysis methods for the preparation of functional Nanoscale Building Blocks (NBB); the product distribution of NBB is determined by random events in solution and the relative reaction rates of the different alkoxide and silane precursors and is therefore poorly controllable;

FIG. 3 quantification of cores collected before shell growth²⁹Si NMR spectrum: DP_{Core, initial}＝1.87；

FIG. 4 quantification of core-shell samples with TEOS-based core and MTES-based shell²⁹Si NMR spectrum: DP_{Core, finally}＝2.40，ΔDP_Core＝2.40-1.87＝0.53，DP_Shell＝1.86，n_Shell/n_Core＝0.09，DP_{General assembly}＝2.35；

FIG. 5 core-Shell sample with TEOS-based core and MTES-based Shell (n)_Shell/n_Core＝0.38、DP_{Core, finally}＝2.33、DP_Shell＝2.08、DP_{General assembly}2.26 from Rad²⁹Si NMR) of²⁹Si-²⁹Si INADEQUATE NMR spectrum and its projection. Peaks are evidence of Si-O-Si covalent bridges between different T and Q species; peaks on diagonal are a pair of adjacent identical species (e.g. Q)²-Q²Or Q³-Q³) Evidence of (a). Adjacent dissimilar species appear as a pair of peaks (e.g., a pair of Ts) that are symmetric around a diagonal²-Q²And Q²-T²Peaks);

FIGS. 6a) to d), presenting terminal chemical functionality and relative content of functional groups (n)_Shell/n_Core) And other model sketches defining the classification of the molecular building blocks by the parameters; and

FIG. 7 is a schematic illustration of the potential use of MBBs according to the invention in the following applications: condensation and/or self-assembly results in the formation of NBB with a uniform composition and customizable surface chemistry.

Detailed Description

Example 1: having n_Core：n_Shell1: synthesis of 0.43 TEOS/MTES core-Shell MBB

i) Production of the core of HypAS, target DP_Core＝1.8/f＝0.9

52g/250mmol Tetraethoxysilane (TEOS) and 0.83ml titanium tetrakis (trimethylsiloxy) (0.75 mol%, relative to TEOS) were placed inside a 250ml round bottom flask with a distillation bridge. 23.2g/225mmol of acetic anhydride Ac were added to the mixture₂O and the glassware set-up was briefly purged with nitrogen, sealed, placed under nitrogen pressure (balloon) and immersed in a hot oil bath at 140 ℃. The reaction mixture was allowed to reach temperature with stirring at 500 rpm. After about 10 minutes from the time of immersion, the reaction started as evidenced by the accelerated reflux rate of the reaction by-product ethyl acetate, which began to pass upwardly into the distillation tube. After about 15 minutes, a continuous stream of ethyl acetate was distilled off through a distillation bridge and collected in a catch vessel. The reaction was continued for a total of about 45 minutes, at which point the reaction ceased, which was reacted with ethyl acetateThe distillation of the ester stopped coincidently. The collection vessel was removed and emptied after a total of 1h of reaction time, yielding a total volume of 41ml of collected reaction by-product mixture.

ii) growth of MTES Shell on the HypAS core, target DP_Shell＝3.6/g＝1.8

In the shell growth step, the reaction mixture from the preceding step a) is stirred at the same reaction temperature (the oil bath is set at 140 ℃) and will consist of 19.15g/107mmol MTES (methyltriethoxysilane) and 19.6g/192mmol acetic anhydride Ac₂The mixture of O was added slowly by means of a syringe pump with constant stirring during about 100 minutes. At the beginning of the MTES/Ac filling₂After about 10-15 minutes from the O mixture, the start of ethyl acetate distillation was again observed. After the addition was complete, the reaction mixture was kept stirring at temperature for an additional 20 minutes, with a total reaction time of the shell growth step of about 2 hours. At the end of the reaction, the heating source was removed from the reaction vessel and the mixture was allowed to cool to room temperature without more ethyl acetate distilling off. The crude product yield was 32.8g of a pale yellow viscous oil. The shell growth step also produced 34ml of distillate collected from the trapping vessel.

Example 2: having n_Core：n_Shell1: synthesis of 0.15 TEOS/VTES core-Shell MBB

i) Production of the core of HypAS, target DP_{Core, initial}＝2.4/f＝1.2

Similarly to example 1i), a hyPAS core derived from TEOS was prepared at the same catalyst amount, temperature and stirring rate. TEOS and Ac used for this synthesis₂The amounts of O were 52g/250mmol and 30.6g/300mmol, respectively, giving an f-th factor of 1.2. The total reaction time was 1 hour and 30 minutes and 55ml of distillate by-product was produced.

ii) growing VTES shells on a hypAS core, g 1.12

Similar to example 1ii), an over growth (overgrowth) of TEOS hyPAS core was prepared, differing mainly in the type and amount of functional trialkoxysilane used for shell growth. Correspondingly, 7.13g/37.5mmol of Vinyltriethoxysilane (VTES) and 4.32g/42mmol of Ac₂O is 30 minutesAnd filling in the clock process. The crude product yield was 32.8g of a slightly viscous, pale yellow oil. The shell growth step also produced 10ml of distillate collected from the trapping vessel.

Examples 3 to 9: synthesis of multiple two-component core-shell MMBs with trialkoxysilane shell chemistry

i) Production of the core of the HypAS

In analogy to example 1i), pure tetraalkoxide hyPAS and mixing core were prepared with the same amount of catalyst, temperature and stirring rate. The amount of tetraalkoxy compound and optional second precursor component functional trialkoxysilane and Ac used for this synthesis₂The amount of O selected can be found in the tables of the experiments above and is in millimoles [ mmol ]]It is given. The reaction time was 1 hour and 30 minutes.

ii) growth of an organofunctional trialkoxysilane shell

In a second step, a shell based on a plurality of organofunctional trialkoxysilanes and mixtures thereof is grown according to the general process described in example 1 ii). The exact reaction parameters are given in the table below. Further, the reaction product is obtained by²⁹Si NMR spectroscopic analysis characterization and Material parameters (DP)_{Core, initial}、DP_{Core, finally}、DDP_Core、DP_Shell、DP_{General assembly}、n_Shell/n_Core) Calculated using the equations given in the earlier discussion.

The set of embodiments presented herein should be considered as experimental evidence of the wide applicability of the method and the wide range of material chemistries available through it.

Examples 10 to 12: having n_Core：n_Shell1: (0.25-0.3) Synthesis of TEOS core/(MTES/DMDES) -Shell MBB

Similarly to example 1i), a hyPAS core material derived from TEOS was prepared at 140 ℃ oil bath temperature with the same amount of catalyst and stirring rate. TEOS and Ac used for this synthesis₂The amounts of O were 52g/250mmol and 25.5g/250mmol, respectively, which corresponds to a f-th factor of 1.0, (DP)_{Core, initial}2.0). The reaction time for core formation was 1 hour and 30 minutes. Condensation collected from the core forming stepThe amount of substance was 45ml in each case, indicating good reproducibility of the core formation step.

After core formation, the oil bath temperature was reduced to 120 ℃ to partially suppress the loss of the more volatile DMDES monomer and the system was allowed to equilibrate for 15 minutes. Shell growth was then triggered by the addition of a Methyltriethoxysilane (MTES)/dimethyldiethoxysilane (DMDES) mixture over the course of 40 minutes by means of a laboratory syringe pump. The table below shows selected shell composition parameters (grey shaded cells) defined by stoichiometric analysis of the added reagents for examples 11 to 13. The g-theoretical factor used in this series is about 1.1.

The material obtained was a clear pale yellow oily liquid. The reaction mixture was then further purified by distilling off unreacted monomers and acetic anhydride by evacuating the reaction vessel to 50 mbar, heating the mixture to 150 ℃ with constant stirring, and holding under temperature/vacuum for a period of 40 minutes.

Examples 13 to 18: gelation testing of NBB hydrolysates derived from (TEOS/MTES) and (TEOS/VTES) core-shell NBB

TEOS/MTES and TEOS/VTES core shells, prepared under the same conditions as given in example 1 but with n changed, were converted to their corresponding NBB hydrolysates respectively using standard hydrolysis procedures_Shell：n_CoreThe ratio sum adjusts the f-factor. NBB sol (hydrolysate) was prepared using the following preparation scheme:

4.32g (6.4ml) ethanol and 3.84 NBB crude mixture with TEOS core/MTES shell were weighed into an Erlenmeyer beaker and heated to 40 ℃ with stirring. After a 5 minute wait period, 15 microliters of 10% H₂SO₄0.27ml of distilled water was added to the mixture. After a short homogenization period, the beaker was closed with parafilm, removed from the heating source and allowed to stand at ambient conditions for 60 hours.

The NBB sol thus obtained was then gelled using the following standard protocol: 7ml of NBB sol was diluted in a 100ml beaker with 16.3ml of absolute ethanol denatured with 2% methyl ethyl ketone and 0.78ml of distilled water. Subsequently, 0.28ml of a 5.5M aqueous ammonia solution was added to the diluted sol and the mixture was stirred for 5 minutes. The activated sol was then transferred to a 50x 50x 20mm square plastic mold and allowed to gel at room temperature and the gelation time was recorded.

From the above examples it can be seen that the gelation time is considerably faster, in particular by comparison with the reference examples given below. Furthermore, for MTES, it is compared with n_Shell/n_CoreThe ratio is completely independent, but for VTES functional materials it follows n_Shell/n_CoreIs increasing and rapidly increasing.

Comparative examples 19 to 24: gelation testing of (TEOS/MTES) and (TEOS/VTES) sols obtained by classical hydrolysis of alkoxylate mixtures

Standard sols were prepared from the same TEOS/MTES and TEOS/VTES compound mixtures using classical hydrolysis and their gelation time was measured for comparison with the MBB- > NBB pathway according to the invention. The TEO to (MTES/VTES) molar ratio was varied in a similar range as in the above examples, with a window range of functional silane to TEOS molar ratios ranging from 0.15 to 0.47.

The sol was prepared in the same manner as the hydrolyzed NBB sol described above: shells of 4.32g (6.4ml) ethanol and 3.84 TEOS/MTES or TEOS VTES mixtures, respectively, were weighed into an Erlenmeyer beaker and heated to 40 ℃ with stirring. After a waiting period of 5 minutes, 15 microliters of 10% H₂SO₄0.27ml of distilled water was added to the mixture. After a short homogenization period, the beaker was closed with parafilm, removed from the heating source and allowed to stand at ambient conditions for 60 hours.

Likewise, gelation tests were conducted using the same gelation protocol as in examples 18-23 above. A summary of the comparative experiments is shown in the table below.

All samples took more than 5 hours to gel and were left to stand overnight. Surprisingly, in the following morning, all samples had gelled. In summary, by comparison, the following becomes clear: sols obtained by classical hydrolysis gelate much slower than their analogues derived from MBB- > NBB sols. This is due to the higher degree of control over the molecular scale building blocks of the sols obtained using the methods described in the present invention.

Overview of the embodiments: