阅读说明：本技术 一种基于阴离子开环聚合机理的三嵌段共聚物及制备方法 (Triblock copolymer based on anion ring-opening polymerization mechanism and preparation method thereof ) 是由 周权 宋宁 于月茹 刘琦 倪礼忠 于 2020-07-06 设计创作，主要内容包括：本发明涉及一种基于阴离子开环聚合机理(ROP)的聚己内酰胺-聚二甲基硅氧烷-聚己内酰胺(PLC-PDMS-PLC)三嵌段共聚物。通过羟基封端的聚二甲基硅氧烷与ε-己内酰胺反应,生成分子量、交联密度可控的三嵌段共聚物。PLC-PDMS-PLC三嵌段共聚物中端羟基聚二甲基硅氧烷链段与环氧树脂不相容,而聚己内酰胺链段与环氧树脂具有良好的相容性,同时聚己内酰胺结构中的酰胺基团可以与环氧树脂发生交联反应,形成三维体型结构。因此将聚己内酰胺-聚二甲基硅氧烷-聚己内酰胺三嵌段共聚物引入环氧树脂中能形成纳米分相结构,起到增韧效果,在航天航空、交通运输及建筑等领域有着广泛的应用。(The invention relates to a polycaprolactam-polydimethylsiloxane-polycaprolactam (PLC-PDMS-PLC) triblock copolymer based on an anion ring opening polymerization mechanism (ROP). The hydroxyl-terminated polydimethylsiloxane reacts with caprolactam to generate the triblock copolymer with controllable molecular weight and crosslinking density. The hydroxyl-terminated polydimethylsiloxane chain segment in the PLC-PDMS-PLC triblock copolymer is incompatible with epoxy resin, the polycaprolactam chain segment has good compatibility with the epoxy resin, and an amide group in the polycaprolactam structure can perform a crosslinking reaction with the epoxy resin to form a three-dimensional structure. Therefore, the polycaprolactam-polydimethylsiloxane-polycaprolactam triblock copolymer is introduced into the epoxy resin to form a nano split-phase structure, has a toughening effect, and has wide application in the fields of aerospace, transportation, buildings and the like.)

1. The invention prepares a polycaprolactam-polydimethylsiloxane-polycaprolactam (PLC-PDMS-PLC) triblock copolymer.

2. The method of preparing the PLC-PDMS-PLC triblock copolymer of claim 1, comprising the steps of:

(1) caprolactam monomer activation: sodium hydroxide and caprolactam monomer are added into the device at room temperature, and the vacuum system device is used to remove moisture and air under the heating state, so that the caprolactam monomer is activated.

(2) Preparing a PLC-PDMS-PLC triblock copolymer: under the protection of inert gas, adding hydroxy polydimethylsiloxane (HO-PDMS-OH) into the activator in the first step, after the reaction is completed, washing the obtained crude product in ethanol to be neutral and drying to finally obtain the PLC-PDMS-PLC triblock copolymer with an amido repeating unit and a siloxane repeating unit.

3. The process of claim 2, wherein the molecular weight of HO-PDMS-OH is 800g/mol to 2000g/mol, the reaction temperature is 80 to 110 ℃, the reaction time is 2 to 4 hours, and the molar ratio of sodium hydroxide to HO-PDMS-OH is 1: (1-3).

4. The PLC-PDMS-PLC triblock copolymer prepared according to claim 2, characterized in that: the molar ratio of HO-PDMS-OH to caprolactam is 1: (10-100), the reaction temperature is 110-130 ℃, and the reaction time is 3-5 hours.

5. The PLC-PDMS-PLC triblock copolymer prepared according to claim 2 is added in the epoxy resin in an amount ranging from 1 to 50 wt%. The epoxy resin is glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, glycidyl ether type epoxy resin, alicyclic epoxy resin and aliphatic epoxy resin.

Technical Field

The invention relates to a preparation method of a polycaprolactam-polydimethylsiloxane-polycaprolactam (PLC-PDMS-PLC) triblock copolymer.

Background

The anion ring-opening polymerization (ROP) is a reaction in which monomers form an anion initiation center by means of an anion initiator, chain growth is carried out by a chain reaction mechanism, and the terminal group of a growing chain formed has a negative charge. In the presence of strong alkali, the initiator and the transition metal complex are halogen atom carriers, and reversible dynamic equilibrium is established between active species and dormant species through redox reaction, so that the control of polymerization reaction is realized. Because the method has the advantages of being suitable for various monomers, being capable of synthesizing polymers with uniform molecular weight, being suitable for various industrial polymerization methods and the like, the method attracts wide attention, and has wide application prospect in the aspects of modified thermosetting resin and the like. The PLC-PDMS-PLC is a novel triblock copolymer, wherein Si-O bonds provided by Polydimethylsiloxane (PDMS) can improve the heat resistance and mechanical property of a system; the introduction of Polycaprolactam (PLC) can increase the number of hydrogen bonds and amide groups, so that the toughness of the system is improved, and meanwhile, amide bonds react with epoxy groups in the epoxy resin, so that the crosslinking density is improved. The compatibility of PDMS and amide chain segments in a matrix is controlled by controlling the proportion of PDMS to the amide chain segments, and a nano phase-splitting structure is formed, so that the system has good comprehensive performance. Therefore, the PLC-PDMS-PLC triblock copolymer has more excellent performance than pure caprolactam and PDMS, utilizes a ring-opening polymerization mechanism, is convenient to control the reaction rate and the reaction degree, is simple to operate, and has mild and safe conditions.

Disclosure of Invention

1. The invention aims to provide a PLC-PDMS-PLC triblock copolymer with better heat resistance and mechanical property, and figure 1 is a structural formula diagram of the polymer, wherein: m and n are integers more than or equal to 1.

2. The invention provides a polymer with a brand-new structure, and a repeating unit of the polymer at least contains a Si-O structure. By adjusting the mass ratio of PDMS to caprolactam to 1 (10-100), the molecular weight and molecular structure of the polymer and the nano phase separation structure of the polymer in the resin can be easily controlled, thereby achieving the purpose of adjustability of the polymer performance.

3. The invention provides a preparation method of a PLC-PDMS-PLC triblock copolymer, which comprises the following steps:

(1) caprolactam monomer activation: mixing caprolactam and sodium hydroxide in a mass ratio of (3-4): 1, keeping a reaction system in a vacuum state, heating and dissolving caprolactam monomer at 110-120 ℃ for 2-3 hours, fully removing water and activating to form activated caprolactam monomer, wherein the figure 2 is a reaction formula diagram thereof.

(2) Preparing a PLC-PDMS-PLC triblock copolymer: under the protection of inert gas, adding hydroxyl-terminated polydimethylsiloxane (HO-PDMS-OH) into an activated caprolactam monomer, carrying out mixed reaction for 3-5 hours according to the amount of the material 1 (10-100), cooling the product to room temperature, washing the product to be neutral by using ethanol, and drying the product in an oven to obtain the PLC-PDMS-PLC triblock copolymer with different molecular weights. The triblock copolymer prepared according to the above description, FIG. 3 is a reaction scheme thereof.

Wherein: FIG. 4 is a structural formula diagram of HO-PDMS-OH

4. The invention starts from the design of molecular structure, PDMS is taken as a chain segment, and the Si-O bond provided by the PDMS is beneficial to improving the heat resistance and the mechanical property of the system; the terminal hydroxyl initiates caprolactam to grow into an amide chain segment, and the provided amide group is beneficial to improving the compatibility of the block copolymer and an epoxy resin system and improving the toughness of the system.

5. According to the invention, from the design of chain segment compatibility, the PDMS chain segment is insoluble in epoxy resin, and the caprolactam chain segment containing amide groups has good compatibility with the epoxy resin matrix, so that the prepared PLC-PDMS-PLC triblock copolymer forms a nano phase-splitting structure in the epoxy resin matrix, and the phase-splitting structure is changed along with the difference of the content of the block copolymer.

The specific embodiment example is as follows:

in order that the invention may be readily understood, the following examples illustrate more particular details, but are not intended to limit the invention.