Siloxane-Ester Copolymers

Synthesis of Segmented Siloxane-Ester Copolymers with (Si—O—C) Linkages 1851 

In both of the above techniques the reactive end-groups on siloxane oligomers were directly bonded to the terminal silicon atoms [i.e. Si—Cl and Si—N(CH3)2 respectively]. Therefore the resultant siloxane carbonate copolymers contained (Si—O—C) 

Synthesis of Bisphenol-A Carbonate-Siloxane Segmented Copolymers152  

Polydimethylsiloxane based multiblock copolymer systems containing 1,1-dichloro-2,2-bis(4-hydroxyphenyl)ethylene polycarbonate units and phenolphthalein polycarbonate units were synthesized and evaluated231 . Both copolymer systems showed good phase separation, increased rubbery character and improved processa- 

transparent, heat and flame resistant, multiblock (bisphenol fluorenone carbonate) (BPF)-dimethylsiloxane copolymers have been synthesized by interfacial polycondensation of phosgene with various mixtures of BPF end-capped siloxane oligomers and free BPF or its monosodium salt 232). Siloxane content of the copolymers were varied between 7 and 27%. Presence of two Tg s, one below —100 °C and the other as high as 275 °C, showed the formation of two-phase morphologies. 

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Recently siloxane-imide copolymers have received specific attention due to various unique properties displayed by these materials which include fracture toughness, enhanced adhesion, improved dielectric properties, increased solubility, and excellent atomic oxygen resistance 1S3). The first report on the synthesis of poly(siloxane-imides) appeared in 1966, where PMDA (pyromellitic dianhydride) was reacted with an amine-terminated siloxane dimer and subsequently imidized 166>. Two years later, Greber 167) reported the synthesis of a series of poly(siloxane-imide) and poly(siloxane-ester-imide) copolymers using different siloxane backbones. However no physical characterization data were reported. 

Poly(unsaturated ester)-siloxane segmented copolymers have been prepared by the polycondensation of epoxy-terminated polydimethylsiloxanes and carboxy-terminated poly(ethylene adipate-co-maleate) oligomers 243). Reactions have been conducted in cellosolve solvent, at 140-150 °C, in the presence of 2% by weight potassium hydroxide catalyst. The molecular weights reported were fairly low. The same group has also prepared poly(hexamethylene adipate)-polydimethylsiloxane copolymers con-... 

Surfactants are used to control cell size and structure. The most common surfactants are siloxane-oxyalkylene copolymers, polyoxyethylene sorbitan fatty acid esters, and the condensation products of ethylene oxide with castor oil and alkyl phenols. A commonly added additive is urea which is used as a formaldehyde scavenger. Very fine particle size inorganic fillers can be added to act as nucleating sites and to promote finer, more uniform cell structure, as well as increased compressive strength, but at a cost of higher density. 

Poly(siloxane)-poly(ester) copolymer surfactant" ... 

M. El Fray, Synthesis and thermal properties of poly(ester-siloxane) multiblock copolymers, Des. Monomers. Polym., 3 325-337,2000. 

Table 16 shows various characteristics of segmented siloxane-(aryl ester) block copolymers. The effect of the variation in the polyester backbone was also studied by replacing bisphenol-A with tetramethyl substituted bisphenol-A. The major difference in these systems was an increase in the high temperature Tg to around 210 to 215 °C 193). 

Synthesis and characterization of ABA type copolymers containing polydimethyl-siloxane or poly(trifluoropropyl,methyl)siloxane middle blocks and aromatic ester based liquid crystalline end blocks were reported 252,253). These materials were synthesized in solution by the reaction of primary or secondary amine-terminated, di-... 

Pubhcations on curing polymers with TAIC include TEE-propylene copolymer (135), TEE-propylene—perfluoroahyl ether (136), ethylene—chlorotrifluoroethylene copolymers (137), polyethylene (138), ethylene—vinyl acetate copolymers (139), polybutadienes (140), PVC (141), polyamide (142), polyester (143), poly(ethylene terephthalate) (144), siloxane elastomers (145), maleimide polymers (146), and polyimide esters (147). 

Methyidithiomethane. See Methyl disulfide Methyl docosanoate. See Methyl behenate Methyl 1, 2, 3, 4, 4a, 4b, 5, 6, 7, 8,10,10a-dodecahydro- 7- isopropyl-1,4a-dimethylphenanthren-1- carboxylate. See Methyl ester of rosin, partially hydrogenated Methyl dodecanoate Methyl n-dodecanoate Methyl dodecylate. See Methyl laurate Methyidodecyl, methyl (2-phenylpropyl) siloxane. See Dodecylmethylsiloxane/2-phenylpropylmethylsiloxane copolymer Methyl eicosanoate... 

Since the cyanobiphenyl derivatives had proved to be excellent materials for electro-optic displays, equivalent homopolymer poly-siloxane liquid crystals, based on these low molar mass mesogens, were synthesized. Their properties are summarized in Table 1. Since the homopolymers only exhibited smectic phases, copolymers were prepared using destabilizing 2-methyl-substituted ester side-groups. As shown in Table 2, at sufficiently high ester-group concentrations, a... 

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