Synthesis of Side-chain Liquid-crystalline Polymers with Narrow Molecular Weight Distribution from Mesogenic Methacrylates Using Aluminum Porphyrin Complex.

Abstract

Synthesis of side-chain liquid-crystalline polymers with narrow molecular weight distribution and controlled molecular weight from mesogenic methacrylates (MEM) with cyano and/or ester groups in their mesogen was achieved through their photopolymerization using (5, 10, 15, 20-tetraphenylporphinato)aluminum methyl (MTPP) as a photosensitizer. The poly(MEM) obtained using MTPP have slightly higher contents of syndiotactic triads and lower contents of isotactic and heterotactic triads than those obtained with a radical initiator. Further, it was found that the tacticities of poly(MEM) are not much different from those of poly(methyl methacrylate) for both the polymerization systems, i.e., polymerizations with MTPP and the radical initiator. Copolymerizations of MEM initiated with MTPP and the radical initiator yielded copolymers with same compositions as those of monomer mixture in feed. Possibility for the control of molecular weight and its distribution of the copolymers obtained using MTPP has been shown. These results opened the way for the synthesis of block copolymers with liquid-crystalline polymeric chain as one component which are considered to form liquid crystals with unique properties, e.g., dimensional stability.