Polyimide Synthesized from Organosilicon Monomer
Jul 13, 2023
Polyimide synthesized from organosilicon monomer with amino groups at both ends. The most commonly used organosilicon monomers of this type are bis (3-aminopropyl) tetramethyldisiloxane and a'w - bis (aminopropyl) polydimethylsiloxane. The siloxane modified polyamide acid was prepared by two different methods, in the mixed solvent of N, N-neneneba dimethylacetamide (DMAc) and tetrahydrofuran (THF) or N-methylpyrrolivanone (NMP) and THF, using benzophenone dianhydride (CBTDA) and aminopropyl terminated polydimethylsiloxane oligomers with different relative molecular weights (950~10000), as well as meta substituted diaminodiaminodiphenyl inkstone (DDS) or diphenylenediamine-1 masking (DABP) chain extenders. The first method is the traditional method of synthesizing polyimide, that is, adding the solid dianhydride into the selected diamine solution; Method 2 is to dropwise add excess BTDA terminated siloxane oligomers to the chain extender DDS or DABP solution. The polyimide siloxane copolymer was prepared by heating, dehydration and cyclization of the reaction mixture film. By adjusting the dosage and relative molecular weight of siloxane oligomers, a series of structurally controllable polymers with high strength, transparency, softness, and solubility can be obtained.
The glass transition temperature of the higher temperature zone is close to that of the unmodified polyimide, which indicates that there is obvious micro phase separation. An analysis was conducted on two methods, and it was found that the first method is only applicable to situations where the relative molecular weight of siloxane oligomers is less than 2000, while the second method is applicable to situations where the relative molecular weight range of siloxane oligomers can be extended to 10000. When using the first method, if the relative molecular weight of the oligomer exceeds 2000, it cannot be guaranteed that all relative molecular weight fractions of the polymer can be dissolved during the polymerization process, resulting in a polymer with appropriate relative molecular weight control.
The thermal polymerization and thermal properties of the copolymer obtained by copolymerization of benzophenone dianhydride, bis (3-aminopropyl) tetramethyldisiloxane and maleic anhydride were studied by DSC, etc. The results showed that the copolymer had good thermal stability, and the interlayer Shear strength between impregnated glass cloth and metal was 17 24kPa. It is reported in the literature that polyimide was synthesized with bis (3-aminopropyl) tetramethyldisiloxane as the diamine component. It was blended with Epikote828 and Xylok resin to produce flexible printed circuit boards, and the flame retardancy reached UL94V-0 grade;
After hot pressing and bonding with copper pins at 160 ° C, the glass strength is 1 3kg/cm, and has good welding resistance at 260 ° C. The permeability of Si CMS obtained by pyrolysis of polyimide siloxane (PIS. There are many reports on the application of aminopropyl (poly) siloxane in Japanese patents, and these products can endow materials with good properties.
Benzoyldiamide, bis (p-aminophenoxy) dimethoxysilane and isophthaloyl chloride diester were used to prepare polyimide containing alcohol. The introduction of oxane units enhances the adhesion of products to substrates (such as Si02); At the same time, with the increase of dioxane content, the dielectric constant of the product gradually decreases, and the gel fraction reaches 88%~90% when the photocrosslinking is carried out under the irradiation of high voltage light collector. A photosensitive organic polyimide LB (Lomgmuir Blodgett) film was synthesized by using bis (aminophenyl) tetramethyldisiloxane as a positive film 25 µ m. The relaxation behavior of polyimides synthesized from positional isomeric di (aminophenyl) disiloxane and di (aminophenyl) hexamethyltrisiloxane in the glass transition region was studied. It was shown that the molecular chain of the para isomeric copolymer has a large conformation and is easy to move. There are also many reports on silicon-containing monomers with amine groups as the active groups at both ends of the reaction.
Polyimide synthesized by introducing silicon containing dianhydride monomer into the main chain structure
Like the silicon containing diamine monomer, the polyimide synthesized by introducing silicon containing dianhydride monomer into the main chain. Mainly through the synthesis of monomers containing siloxane component dianhydride and siloxane component dianhydride. Then prepared by reacting these monomers with corresponding diamines. Therefore. The synthesis of silicon containing dianhydride monomer is the key to prepare this type of silicon containing polyimide.
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