A Model Chiral Graft Copolymer Demonstrates Evidence of the Transmission of Stereochemical Information from the Side Chain to the Main Chain on a Nanometer Scale

A model chiral graft copolymer, poly(phenylacetylene)-g-poly(n-hexyl isocyanate) (PPA-g-PHIC), in which a chiral moiety is located at the end of each PHIC side chain, was synthesized. First, chiral PHIC macromonomers with a phenylacetylene end group were synthesized via living anionic polymerization using the functional initiator sodium N-(4-ethynylphenyl)benzamide (Na-4EPBA) and then end-capped using the chiral terminator (S)-2-acetoxypropionyl chloride ((S)-Ct). The molecular weights (MWs) of the PHIC macromonomers were controlled based on the feed ratio of the monomer to the initiator. Subsequent polymerization of PHIC macromonomers using Rh+(2,5-norbornadiene)[(η6-C6H5)B–(C6H5)3] (Rh(nbd)BPh4) catalyst generated chiral PPA-g-PHIC graft copolymers with varying graft strand lengths. Chiral macromonomers and graft copolymers were characterized by SEC-MALLS, NMR, and CD spectroscopy. This model chiral graft copolymer provided an excellent example of the transmission of stereochemical information from the ...