Polysiloxane Polyimides

PEEK can be blended with polyimide/siloxane copolymers to produce materials with improved ductility. Such materials may be suitable 

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Yilgor I, Yilgor E, Johnson BJ, Eberle J, Wilkes GL, McGrath JE (1983) Segmented polysiloxane-polyimide copolymers. Polymer Preprints 24(2) 78... 

Sysel P, Babu JR, Konas M, Riffle JS, McGrath JE (1992) Preparation and evaluation of arylamine containing polysiloxane-polyimide block copolymers Polym Prepr (Am Chem Soc Div Polym Chem) 33 2 218... 

Kang C, Eiss NS, Jr. (1992) Fretting wear of polysiloxane-polyimide copolymer coatings as a function of varying humidity wear. Wear 158(1—2) 29... 

Hydrosilylation of BMI with l,4-bis(dimethylsilyl)benzene leads to the formation of polysiloxane polyimide [69]. 

In another approach to copolymers, linear H-terminated polysiloxanes are hydrosilated to introduce reactive groups. Examples are the addition of allylamine to give reactive intermediates that can be converted to polysiloxane-polyimides or polyamides, and the hydrosilylation of allyl glycidyl ether to produce a silicone that can be copolymerized with epoxides or acrylates (equations 29 and 30). 

More recently, we have also reported the synthesis of thermoplastic siloxane elastomers based on hybrid polysiloxane/polyimide block copolymers (the hybrid polysiloxane being fluorinated or not) that were obtained through polyhydrosilylation of dienes with a,dihydrooligosiloxanes [76-78], as follows ... 

Stability of polysiloxane-polyimides to oxygen plasmas was attributed to formation of a silica overlayer by Yilgor, I., Yilgor, E., Spinu, M. Polymer Preprintsl9S7, 23, 84. 

As mentioned earlier, siloxanes impart a number of beneficial properties to polymeric systems into which they are incorporated, including enhanced solubility, resistance to degradation in aggressive oxygen environments, impact resistance and modified surface properties. These particular advantages render polysiloxane-modified polyimides attractive for aerospace, microelectronic and other high performance applications (40-43). 

Recently Sulzer, working with Grace Davison [35,59] and using polyimide, polysiloxane or polyurea urethane membranes, and ExxonMobil [60], using Nation or cellulose triacetate membranes, have described processes to separate sulfur compounds from various refinery streams. 

Sysel P,Oupicky D (1996) Polyimide-polysiloxane block copolymers synthesized from alpha omega-(3-aminophenoxy)-terminated poly[oxy(dimethylsilyl)-14-phenylene (dimethylsilylene)]s Polym Int49(4) 275... 

Furukawa N, Yausa M, Yamada Y, Kimura Y (1998) Synthesis and properties of novel thermosetting polysiloxane-block-polyimides with vinyl functionality. Polymer... 

Furukawa N, Yamada Y, Furukawa M.YuasaM, KimuraY (1997) Surface and morphological characterization of polysiloxane-block-polyimides. J Polym Sci Part A Polym Chem 35(11) 2239... 

Furukawa N, Yamada Y, Kimura Y (1996) Preparation and stress relaxation properties of thermoplastic polysiloxane block polyimides. High Perform Polym 8(4) 617... 

Tian SB,Pak YS,Xu G (1994) Polyimide-polysiloxane-segmented copolymers as high temperature polymer electrolytes. J Polym Sci Part B Polym Physics 32 2019... 

Because PBI is expensive, other thermostable polymers were explored and tested as catalysts (246). A cross-linked version of a polyimide (PI) support with incorporated triazole rings (12b) gave better results than PBI for the epoxidation of cyclohexene. Moreover, it can be reused in the cyclohexene epoxidation at least 10 times without any loss of activity (247). Even less expensive, but thermooxidatively stable materials include polysiloxane-based resins, which have also been used for incorporation of Ti (see Section II,A). In this case, the synthesis comprises the polymerization of TEOS and an oligomeric dimethyl silanol with the addition of functional trialkoxysilanes such as trimethoxysilyl-2-ethylpyridine instead of Ti(OiPr)4 (248). Preliminary results show that the activity per Mo atom is higher than that of PBI-Mo. Furthermore, the degree of leaching of Mo is very low. Thus, it is expected that the polysiloxane-based systems may soon find wide application in oxidation chemistry. 

The polymers and copolymers described in this chapter were derived fi"om the novel anhydride-terminated disiloxane, 5,5 -bis(l,l,3,3-tetra-methyl-1,3-disiloxanediyl)norbornane-2,3-dicarboxylic anhydride (DiSiAn) (14). Both siloxane-polyimide polymers and copolymers based on DiSiAn and its polysiloxane derivatives were investigated. This chapter describes the synthesis, characterization, and physical properties of these materials. 

Siggia and co-workers proposed methods for the determination of carboxylic esters [262], polysiloxanes [263] and imides, aromatic polyimides, polyamides and poly-(amide-imides) [264] by alkali fusion reaction GC. 

The selective stationary phases were further divided in the scheme proposed by Horning et al. [79] for the steroid separations into the types selective to alcohols, ketones, multiple bonds, etc. Here, various selective interactions between the column and the separated solutes are utilized. Most importantly, various polyglycols, polyesters, polyphenyl ethers, polyamides and polyimides belong to these categories. In addition, substitution of an alkyl group in a polysiloxane polymer by a more polar... 

The specialty resins are expensive, produced in relatively small volumes either for a specific application or looking for a market niche. Their Tg > 200°C and modulus > 3 GPa. In 1991 the total world consumption of polysulfones (PSE) and polyethersulfones (PES) was 8.5 kton. Blends of the following polymers are known polyfluorocarbons, polysiloxanes, sulfur-containing polymers (PPS, PPSS, PES, and PSF), polyetherk-etones (PEK, PEEK, PEKK), polyimides (PI, PEI, and PAI), PAr, COPO, polyphosphazene (PHZ) and LCP. 

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