LIQUID-CRYSTALLINE SIDE-CHAIN POLYSILOXANES WITH 4-AMINO-4'-STILBENECARBOXYLIC ESTER MESOGENS

Side chain polysiloxanes with 4-(dimethylamino)- and 4-[4-(hexyloxy)piperidino]-4'-stilbenecarboxylic ester mesogens were synthesized from poly(hydromethylsiloxane) and poly(hydromethylsiloxane-co-dimethylsiloxane) and the 10-undecen-1-yl esters. Size exclusion chromatography (SEC) underestimates M(n) of the (dimethylamino)stilbene homopolymer by a factor of 4 and M(n) of the piperidinoetilbene homopolymer by a factor of 2 compared with H-1 NMR end group analyses. SEC and NMR values of M(n) approximately agree for the copolymers. The phases of the monomers and polysiloxanes were assigned by polarizing microscopy and X-ray diffraction. The copolysiloxanes have T(g) near -40-degrees-C by DSC, but T(g) was not detected for the homopolysiloxanes. Both homopolysiloxanes have nematic phases, and both copolymers have S(A) phases. The [(hexyloxy)piperidino]stilbene polymers have more ordered phases, assigned ag S(B) of the copolymer and either S(B) or hexagonal nematic of the homopolymer. The isotropic transitions were detected by polarizing microscopy but not by DSC. All of the polysiloxanes form stable monolayers on water that can be compressed to mean areas per stilbene repeat unit ranging from 23 to 34 angstrom2 and to pressures of greater-than-or-equal-to 50 mN/m.