SYNTHESIS AND CHARACTERIZATION OF OPTICAL-ACTIVE AND AMPHIPHILIC GRAFT COPOLYMERS OF POLYACETYLENE-MPEG

Abstract

The novel graft copolymers of(poly(a-co-b),(a:propiolic acid L-menthol ester;b:propiolic acid polyethylene glycol monomethyl ether ester)) having C-chirality and hydrophilic macromolecules as pendant groups were synthesized via copolymerization of monomer a and monomer b by using(nbd)Rh +[η6-C6H5B-(C6H5)3]as catalyst.The structure of copolymers was characterized by FTIR.Moderate molecular weights(Mn)(13000 ～ 15000) and Mw /Mn(2.1 ～ 2.2) of copolymers were measured by GPC.The maximum amount of MPEG for successful copolymerization of copolymers was 20 mol%.The optical activity and secondary structure of the copolymers were characterized by specific rotations([α]D) and circular dichroism(CD) spectra.The copolymers with relatively low yields(32.3% ～ 46.6%) exhibited high optical activity in contrast to chiral monomer,which accorded with the"Chiral Amplification"effect.All the copolymers formed single helical conformation in despite of adding the long chain of MPEG.Certainly,the optical activity of copolymers decreased with the increase of MPEG content.The helical conformation of the copolymers kept the better stability in CHCl3 comparing to other three selective solvents.As the time delay,the optical activity of the copolymers decreased due to their instability.By adding the hydrophilic chain of MPEG,rigid and flexible chain were linked finely and formed the hydrophilic /hydrophobic interaction,which provided the best driving force for self-assembly behavior.