Synthesis and Side Chain Liquid Crystal Polymers by Living Ring Opening Metathesis Polymerization. 5. Influence of Mesogenic Group and Interconnecting Group on the Thermotropic Behavior of the Resulting Polymers
MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF CHEMISTRY
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Norbornene derivatives containing 4-cyano-4-biphenyloxy mesogens linked to the norbornene through methylene groups n 3-7, 9-12 and an ester were polymerized by MoCHRNArO-t-Bu2 Ar 2,6-C6H3-i-Pr2, R t-Bu in a living manner. Polymers in which n 3 were amorphous, whereas all other polymers n 4-7, 9-12 displayed enantiotropic nematic mesophases that were independent of the molecular weight. Polymers having 9-12 methylene spacers did not undergo side chain crystallization and did not show an odd-even effect, in contrast to analogous polymers containing 4-methoxy-4-biphenyloxy mesogens, which exhibited side chain crystallization when n 8 and an odd-even effect when n 7. The lower tendency to form a more ordered phase and the absence of an odd-even effect are attributed to dipole-dipole repulsions between 4-cyano- 4-biphenyloxy mesogens. Polymers containing 4methoxy-4-biphenyloxy mesogens attached through ether linkages gave highly crystalline SCLPCs, even with relatively few spacers n 4-6 . polymers, SCLPCs side chain liquid crystalline polymers, block copolymers, mesogens.
- Organic Chemistry
- Polymer Chemistry