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Journal of Polymer Science Part A: Polymer Chemistry, Vol.38, No.23, 4315-4325, 2000
Synthesis and polymerization of chiral methacrylates bearing a cholesteryl or menthyl group
Chiral methacrylates, that is, cholesteryl (ChMOC) and I-menthyl (MnMOC) N-(2-methacryloyloxyethyl)carbamates, were synthesized from 2-methacryloyloxyethyl isocyanate and cholesterol and l-menthol, respectively. Radical polymerizations of ChMOC and MnMOC gave number-average molecular weights for poly(ChMOC) and poly(MnMOC) of up to 3.74 x 10(4) and 9.39 x 104, respectively, and the specific rotations ([alpha](435)(25)) were -43.1 degrees to -47.7 degrees and -87.6 degrees to -89.0 degrees, respectively. Temperature dependence of the specific optical rotation was observed for poly(ChMOC) but not for poly(MnMOC). The hydrogen bonds based on urethane segments for poly(ChMOC) were stronger than those for poly(MnMOC) according to IR spectra. In addition, the chiroptical properties of poly(ChMOC) were slightly affected by temperature in the presence of trifluoroacetic acid acting as an inhibitor for the formation of hydrogen bonds. Therefore, poly(ChMOC) may have a regular conformation due to hydrogen bonds and interaction between cholesteryl groups. Radical copolymerizations of ChMOC with styrene, methyl methacrylate, N-cyclohexylmaleimide, and N-phenylmaleimide were performed with 2,2'-azobisisobutyronitrile in tetrahydrofuran at 60 degreesC. Monomer reactivity ratios and Alfrey-Price Q-e were determined. Chiroptical properties of the copolymers were influenced by co-units. Thermal and X-ray diffraction analyses were performed for the homopolymers and copolymers.
Keywords:2-methacryloyloxyethyl isocyanate;radical polymerization;hydrogen bond;chiral methacrylate;optically active polymer;monomer reactivity ratios