阅读说明：本技术 聚苯并噁嗪交联的耐水解聚硼硅氧烷及其制备方法 (Polybenzoxazine crosslinked hydrolysis-resistant polyborosiloxane and preparation method thereof ) 是由 鲁在君 高生 孙露露 于 2019-08-27 设计创作，主要内容包括：本发明涉及聚苯并噁嗪交联的耐水解聚硼硅氧烷及其制备方法,依次将酚类、甲醛类、胺类、有机溶剂,加入反应瓶中,进行加热搅拌一段时间,反应结束后冷却至室温,旋转蒸发除去有机溶剂,得到含硅苯并噁嗪单体；再将所得苯并噁嗪单体和含硼化合物反应得到含苯并噁嗪侧基的硼硅氧烷预聚物；最后将所得预聚物热固化交联到聚苯并噁嗪交联的聚硼硅氧烷。本发明首次将苯并噁嗪侧基与硼硅氧烷连接起来制备了聚苯并噁嗪交联的聚硼硅氧烷杂化材料,成功解决了普通的聚硼硅氧烷的易水解性的问题。(The invention relates to a polybenzoxazine crosslinked hydrolysis-resistant polyborosiloxane and a preparation method thereof, which comprises the steps of sequentially adding phenols, formaldehydes, amines and an organic solvent into a reaction bottle, heating and stirring for a period of time, cooling to room temperature after the reaction is finished, and removing the organic solvent by rotary evaporation to obtain a silicon-containing benzoxazine monomer; then reacting the obtained benzoxazine monomer with a boron-containing compound to obtain a borosiloxane prepolymer containing benzoxazine side groups; finally, the resulting prepolymer is thermally cured and crosslinked to a polybenzoxazine crosslinked polyborosiloxane. According to the invention, the benzoxazine side group and the borosiloxane are connected for the first time to prepare the poly-borosiloxane hybrid material crosslinked by the polybenzoxazine, and the problem of easy hydrolyzation of common poly-borosiloxane is successfully solved.)

1. A polybenzoxazine crosslinked hydrolysis resistant polyborosiloxane characterized by having a structure represented by formula (VII) or (VIII) or (IX):

Wherein:

n is an integer of 1 to 1000.

2. a method of preparing a polybenzoxazine crosslinked hydrolysis resistant polyborosiloxane of claim 1 comprising the steps of:

The preparation method comprises the steps of taking a silicon-containing benzoxazine monomer and a boron compound as raw materials, taking an oil-soluble solvent as a solvent, preparing a borosilicate siloxane prepolymer containing benzoxazine side groups by a condensation polymerization method, and further carrying out thermal ring-opening cross-linking polymerization to obtain the polybenzoxazine cross-linked hydrolysis-resistant polyborosiloxane.

3. The method for preparing polybenzoxazine crosslinked hydrolysis-resistant polyborosiloxane according to claim 2, wherein the silicon-containing benzoxazine monomer has the structure shown in (I), (II) or (III):

4. The preparation method of the polybenzoxazine crosslinked hydrolysis-resistant polyborosiloxane according to claim 3, wherein the silicon-containing benzoxazine monomer is prepared by the following steps:

Sequentially adding 30-80 parts by weight of phenolic compound, 30-80 parts by weight of amine compound, 20-50 parts by weight of aldehyde compound and 40-100 parts by weight of solvent into a reaction vessel, stirring, and reacting at 50-110 ℃ for 1-48 hours; stopping heating, cooling, and removing the solvent to obtain the benzoxazine monomer.

5. The method for preparing polybenzoxazine crosslinked hydrolysis-resistant polyborosiloxane according to claim 4, wherein the phenolic compound is one of phenol, bisphenol F, bisphenol A, 4 '-dihydroxybenzophenone, 4' -dihydroxybiphenyl sulfoxide, and biphenyltrisphenol; the amine compound is gamma-aminopropylmethyldimethoxysilane or gamma-aminopropylmethyldiethoxysilane, and the aldehyde compound is paraformaldehyde or a formaldehyde water solution with the mass concentration of 37%;

Preferably, the solvent is any one of water, tetrahydrofuran, acetone, N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, dioxane, chloroform and toluene.

6. The preparation method of the polybenzoxazine crosslinked hydrolysis-resistant polyborosiloxane according to claim 4, wherein the mass ratio of the phenolic compound to the amine compound to the aldehyde compound to the solvent is 1 (0.9-8.5) to 80 (1.6-2.5), so as to obtain the compound shown in the formula (I);

Or the mass ratio of the phenolic compound, the amine compound, the aldehyde compound and the solvent is 1 (1.2-2.5) to 80 (1.7-2.2), so as to obtain a compound shown in a formula (II);

Or the mass ratio of the phenolic compound, the amine compound, the aldehyde compound and the solvent is 1 (1.5-2.8) to 80 (2.1-3.6), so as to obtain the compound shown in the formula (III).

7. The method for preparing polybenzoxazine crosslinked hydrolysis-resistant polyborosiloxane according to claim 2, wherein the borosiloxane prepolymer containing benzoxazine side groups has a structure shown in formula (IV) or (V) or (VI):

8. The method for preparing polybenzoxazine crosslinked hydrolysis-resistant polyborosiloxane according to claim 7, wherein the method for preparing the polybenzoxazine side group-containing borosiloxane prepolymer comprises the following steps:

Mixing a silicon-containing benzoxazine monomer with a boron compound, reacting for 3-5 h at 70-120 ℃ with or without a catalyst, stopping heating, and cooling to obtain the borosilicate siloxane prepolymer containing the benzoxazine side group.

9. The method for preparing polybenzoxazine crosslinked hydrolysis-resistant polyborosiloxane according to claim 8, wherein the boron compound is boric acid or phenylboronic acid; when a catalyst is used, the catalyst is hydrochloric acid; the reaction temperature is 120 ℃, and the reaction time is 5 h.

10. The method for preparing polybenzoxazine crosslinked hydrolysis-resistant polyborosiloxane according to claim 2,

Thermally curing the benzoxazine-containing borosiloxane prepolymer at 80-220 ℃ for 8-16 hours to obtain polybenzoxazine cross-linked polyborosiloxane;

Preferably, the borosiloxane prepolymer containing benzoxazine side groups is dissolved in a solvent, and is subjected to film formation through a casting method and thermal curing; the solvent is any one of toluene, N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, dichloromethane, chloroform, dioxane and tetrahydrofuran.

Technical Field

The invention relates to a novel polyborosiloxane hybrid material crosslinked by polybenzoxazine, in particular to novel hydrolysis-resistant polyborosiloxane and preparation thereof.

Background

polyborosiloxane (PBS) is a polymer obtained by substituting some of the silicon atoms in the polysiloxane skeleton with boron atoms, and has the following formula:

Wherein R1 and R2 are alkyl, aryl, hydrogen, oxygen, etc., and R3 is oxygen, aryl, etc.

in the molecular chain of PBS, the bond energy of B-O and Si-O is respectively up to 537.6kJ/mo1 and 422.5kJ/mol, and p-pi and d-pi conjugate effects exist, so that the common use temperature of some PBS can reach 450 ℃ and the maximum use temperature can reach 550 ℃, and the heat resistance of the PBS is far higher than that of the conventional polyimide (the common use temperature is 200 ℃ and the maximum use temperature is 250 ℃). The ceramic fiber prepared by using PBS as a precursor has outstanding oxidation resistance, the weight loss starts only at 700 ℃, and the residue at the temperature of more than 1000 ℃ still keeps 40 percent which is higher than that of pure carbon fiber (30 percent). Therefore, the PBS can be used for preparing heat-resistant coatings, heat-resistant adhesives, environment-friendly flame retardants, antioxidant ceramics and the like, and is particularly used as a heat-resistant material with the long-term use temperature of 450 ℃, which arouses great interest of researchers.

In the aspect of the synthesis development process of PBS, in 1960, Vale firstly synthesizes polyborodimethylsiloxane by condensing dimethyldichlorosilane and boric acid, and the polyborodimethylsiloxane has good heat resistance, but because the polarity of a B-O bond is stronger than that of a Si-O bond, the tendency of carrying out an ionic reaction is increased, and the product is very easy to hydrolyze in air and cannot be applied. In the middle of the 70's, Yajima et al synthesized polyborodiphenylsiloxane in a similar manner, with a much improved water resistance, but still less desirable. So far, the synthesis of PBS has been reported sporadically at home and abroad, for example, Zhanhongwei uses hydroquinone to modify polyborodiphenylsiloxane, Besseling uses polydimethylsiloxane as raw material to synthesize PBS, but the PBS still has no great breakthrough in hydrolysis resistance and is in a slowly developing state.

In addition, CN107868252A discloses a hyperbranched polyborosiloxane containing functional groups, which has the characteristics of hyperbranched topological structure, stable storage performance, controllable viscosity, and the like, and has excellent compatibility with the existing polymer materials. CN107312175A discloses a preparation method of linear polyborosiloxane, which specifically refers to a preparation method of linear polyborosiloxane by removing hydrogen under the catalysis of tris (pentafluorobenzene) borane by taking tetramethyldisiloxane, diorganodialkoxysilane and phenylboronic acid as raw materials. However, none of the above polyborosiloxanes was investigated for hydrolysis performance. The molecular structure of the synthesized polyborosiloxane still does not solve the problem of hydrolysis resistance. JP2015168804A discloses a process for producing a polyborosiloxane which is improved in hydrolysis resistance by introducing a benzene ring into the polyborosiloxane, but the improvement is not so great that the product cannot be exposed to air for a long period of time.

Polybenzoxazines (PBZ) are a new class of heat-resistant resins that have emerged internationally in recent years with a number of outstanding advantages, such as (i) high cost performance: the heat resistance is better than that of phenolic aldehyde and epoxy resin, and is comparable to that of bismaleimide, but the price of the bismaleimide resin is only half of that of the bismaleimide resin. Excellent flame retardancy: because of the nitrogen element, the intrinsic flame retardance is better than that of the phenolic resin. Flexible variability of molecular design: a variety of phenols and amines can be linked together in a "one-pot" process. Therefore, the attention of researchers at home and abroad to polybenzoxazines is continuously increased.

At present, benzoxazine groups are introduced into polyborosiloxane to obtain a polyborosiloxane hybrid material crosslinked by polybenzoxazine, and reports are not found.

Disclosure of Invention

Aiming at the defects of the prior art, in particular to the defect of poor hydrolysis resistance of the existing polyborosiloxane, the invention provides a polybenzoxazine crosslinked hydrolysis-resistant polyborosiloxane and a preparation method thereof. The preparation method comprises the steps of firstly, taking aminopropylsilane, phenol and paraformaldehyde as raw materials, synthesizing a series of benzoxazine monomers containing siloxane groups by utilizing benzoxazine chemical design, then carrying out polycondensation on the siloxane groups and boron compounds to obtain a PBS prepolymer containing the benzoxazine side groups, and finally carrying out thermal ring opening reaction to obtain the polyborosiloxane (PBS-PBZ) crosslinked by benzoxazine ring opening polymerization.

The technical scheme of the invention is as follows:

A polybenzoxazine crosslinked hydrolysis resistant polyborosiloxane (PBS-PBZ) having the structure of formula (VII) or (VIII) or (IX):

Wherein: r1 ═ CH2,

R3 is OH or

n is an integer of 1 to 1000.

According to the invention, the preparation method of the polybenzoxazine crosslinked hydrolysis-resistant polyborosiloxane (PBS-PBZ) comprises the following steps:

The preparation method comprises the steps of taking a silicon-containing benzoxazine monomer and a boron compound as raw materials, taking an oil-soluble solvent as a solvent, preparing a borosilicate siloxane prepolymer containing benzoxazine side groups by a condensation polymerization method, and further carrying out thermal ring-opening cross-linking polymerization to obtain the polybenzoxazine cross-linked hydrolysis-resistant polyborosiloxane.

The silicon-containing benzoxazine monomer has a structure shown in (I), (II) or (III):

The preparation method of the silicon-containing benzoxazine monomer comprises the following steps:

sequentially adding 30-80 parts by weight of phenolic compound, 30-80 parts by weight of amine compound, 20-50 parts by weight of aldehyde compound and 40-100 parts by weight of solvent into a reaction vessel, stirring, and reacting at 50-110 ℃ for 1-48 hours; stopping heating, cooling, and removing the solvent to obtain the benzoxazine monomer.

Preferably, 40-80 parts by weight of phenolic compound, 40-75 parts by weight of amine compound, 30-50 parts by weight of formaldehyde and 70-95 parts by weight of solvent are sequentially added into a reaction vessel, stirred and reacted for 12-36 hours at 75-100 ℃; stopping heating, cooling, removing the solvent, and drying in vacuum to obtain the benzoxazine monomer.

preferably, the phenolic compound is one of phenol, bisphenol F, bisphenol a, 4 '-dihydroxybenzophenone, 4' -dihydroxybenzophenone sulfoxide and biphenyltriphenol.

preferably, the amine compound is γ -aminopropylmethyldiethoxysilane.

Preferably, the aldehyde compound is paraformaldehyde or a 37% formaldehyde aqueous solution.

preferably, the solvent is any one of water, tetrahydrofuran, acetone, N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, dioxane, chloroform and toluene.

According to the preparation method of the silicon-containing benzoxazine monomer, the mass ratio of the phenolic compound to the amine compound to the aldehyde compound to the solvent is preferably 1 (0.9-8.5) to 80 (1.6-2.5), so that the compound shown in the formula (I) is obtained;

Or the mass ratio of the phenolic compound, the amine compound, the aldehyde compound and the solvent is 1 (1.2-2.5) to 80 (1.7-2.2), so as to obtain a compound shown in a formula (II);

Or the mass ratio of the phenolic compound, the amine compound, the aldehyde compound and the solvent is 1 (1.5-2.8) to 80 (2.1-3.6), so as to obtain the compound shown in the formula (III).

And (3) drying the product at 50-90 ℃ for 6-24 hours in vacuum to obtain the refined silicon-containing benzoxazine monomer.

preferably, the vacuum drying temperature is 40 ℃ and the vacuum drying time is 24 hours.

the benzoxazine side group-containing borosiloxane prepolymer has a structure shown as a formula (IV) or (V) or (VI):

According to the present invention, preferably, the preparation method of the borosilicate prepolymer containing benzoxazine side groups comprises the following steps:

And mixing the obtained benzoxazine-containing monomer with a boron compound, reacting for 3-5 h at 70-120 ℃ with or without a catalyst, stopping heating, and cooling to obtain the borosilicate siloxane prepolymer containing the benzoxazine side group.

Preferably, the boron compound is boric acid or phenylboronic acid.

Preferably, the reaction conditions are carried out without using a catalyst; when a catalyst is used, the catalyst is hydrochloric acid.

Preferably, the reaction temperature is 120 ℃.

Preferably, the reaction time is 5 h.

According to the invention, the polybenzoxazine crosslinked polyborosiloxane has a structure represented by formula (VII) or (VIII) or (IX):

According to the invention, the polyborosiloxane crosslinked by polybenzoxazine is obtained by carrying out thermal ring-opening crosslinking polymerization on a borosiloxane prepolymer containing benzoxazine side groups, and the preparation method comprises the following steps:

And thermally curing the benzoxazine-containing borosiloxane prepolymer at 80-220 ℃ for 8-16 hours to obtain the polybenzoxazine cross-linked polyborosiloxane PBS-PBZ.

more preferably, the borosiloxane prepolymer containing benzoxazine side groups is dissolved in a solvent, and is subjected to film formation by a casting method and thermal curing; the solvent is any one of toluene, N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, dichloromethane, chloroform, dioxane and tetrahydrofuran.

The invention firstly provides a new idea of crosslinking the PBS oligomer by using the benzoxazine group. Because a unique molecular structure is generated after ring opening polymerization of benzoxazine: the molecular chain of the hydrolysis-resistant polyester resin contains nitrogen atoms and phenolic hydroxyl groups, and the nitrogen atoms can form coordinate bonds with boron atoms, so that hydrolysis reaction is hindered, and a breakthrough is made in the aspect of improving hydrolysis resistance. In addition, the phenolic hydroxyl group can undergo a thermally reversible reaction at high temperatures, similar to transesterification, with Si-O-B, resulting in "reworkable" properties. Therefore, a novel hydrolysis-resistant, high Tg and reprocessable PBS can be obtained.

The invention has the following remarkable advantages:

1. The invention synthesizes the poly-benzoxazine cross-linked polyborosiloxane PBS-PBZ for the first time and has excellent hydrolysis resistance. The appearance and quality of the samples did not change significantly after 6 months immersion in water.

2. according to the polybenzoxazine cross-linked polyborosiloxane PBS-PBZ, due to the existence of a benzoxazine structure and boron atoms, nitrogen atoms and boron atoms formed by ring opening of an oxazine ring generate a coordination effect, so that the hydrolysis resistance of the PBS-PBZ is remarkably improved compared with that of common polyborosiloxane, the polyborosiloxane can exist in the air for a long time, and the application of the polyborosiloxane is widened.

3. The synthetic route of the polybenzoxazine crosslinked polyborosiloxane PBS-PBZ is simple and easy to implement, and the adopted main raw materials are from commercial products, so the synthetic cost of the polybenzoxazine crosslinked polyborosiloxane PBS-PBZ is relatively low, and the polybenzoxazine crosslinked polyborosiloxane PBS-PBZ is easy for industrial production.

Drawings

FIG. 1 shows FT-IR spectra of a benzoxazine-containing monomer a obtained in example 2 of Experimental example 1, a borosilicate prepolymer b having a monocyclic benzoxazine-containing side group obtained in example 12, and a polybenzoxazine-crosslinked polyborosiloxane c obtained in example 18.

FIG. 2 is a 1H NMR spectrum of a borosiloxane prepolymer containing pendant monocyclic benzoxazine groups obtained in example 12 of Experimental example 1.

FIG. 3 is a 11B NMR spectrum of a borosiloxane prepolymer containing pendant monocyclic benzoxazine groups obtained from example 12 of Experimental example 1.

FIG. 4 TGA curve of polybenzoxazine crosslinked polyborosiloxane PBS-PBZ from example 18 of Experimental example 2.

FIG. 5 is a photograph showing an experiment of hydrolysis resistance of the polybenzoxazine-crosslinked polyborosiloxane PBS-PBZ synthesized in example 3.

Detailed Description

The present invention will be further described with reference to the accompanying drawings and examples, which are provided for the purpose of illustration only and are not intended to limit the scope of the invention.