Synthesis and Helical Properties of N-Substituted p-Benzamide Random Copolymers Possessing Chiral/Achiral and (S)/(R) Side Chains

Random copolymers of poly(p-benzamide)s having a methyl-substituted tri(ethylene glycol) unit as a chiral side chain and a nonsubstituted tri(ethylene glycol) or branching alkyl unit as an achiral side chain were synthesized by copolymerization of N-substituted 4-aminobenzoic acid ester monomers with a base in the presence of an initiator. Copoly-merizations of the chiral (S)-monomer with N-tri(ethylene glycol) achiral monomer and with the racemic monomer were carried out by the addition of a mixture of two monomers and an initiator to a solution of a base all at once, affording the corresponding random copolymers. On the other hand, random copolymerization of the chiral monomer with monomer having an achiral branching alkyl side chain required dropwise addition of the achiral monomer to a mixture of the chiral monomer, the initiator, and the base. These copolymers formed helical structures, but analysis of the CD spectra indicated the absence of cooperativity between the monomer units along the copolymers. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 1387-1395,2011