Synthesis of Thermotropic Liquid Crystalline Side-Chain Polymers via Chemical Modification of Polymeric Carboxylic Acids

摘要

Esterification of poly(acrylic acid) and poly (methacrylic acid) with relatively bulky alkyl halides via the corresponding tetrabutylammonium salts in dimethylformamide was conducted by following three different procedures. The following observations were made: 1) the presence of methanol and water was detrimental to the desired reaction on the polymeric substrate, 2) the excess tetrabutylammonium hydroxide in the presence of a small amount of water caused the hydrolysis of base-sensitive alkylating agents, and 3) residual water accompanying polymeric carboxylate was conducive to the enhancement of the degree of substitution and product yield for alkylating agents that can survive the basic condition. For the base-sensitive alkylating agent, it is essential that residual tetrabutylammonium hydroxide be removed. The product showed liquid crystallinity with a degree of substitution as low as 25% for the polyacrylate backbone. For the stiffer polymethacrylate backbone, a degree of substitution of a least 40% is needed for mesophase formation. Reprints. (AW)