Synthesis of a novel one-handed helical poly(phenylacetylene) bearing poly(l-lactide) side chains

摘要

The living ring-opening polymerization of l-lactide was carried out by using organocatalyst to synthesize the molecular weight controlled poly(l-lactide) with an phenylacetylenyl end group (HCCPLLA), then the homopolymerization of HCCPLLA was performed by using two different rhodium catalysts. Low molecular weight poly-PLLA_6-1 (M_(w,SEC-MALLS) = 46,700) was synthesized by using Rh(nbd)BPh_4 as the catalyst, and higher molecular weight poly-PLLA_6-2 (M_(w,SEC-MALLS) = 471,000) was synthesized by using the [Rh(nbd)Cl]_2/Et_3N catalyst system. Then high molecular weight poly-PLLA_(20), poly-PLLA_(29), and poly-PLLA_(68) were successfully synthesized by using the [Rh(nbd)Cl]_2/Et_3N catalyst system. The α values of the poly-PLLAs using [Rh(nbd)Cl]_2/Et_3N catalyst system were all in the range of 0.6-0.8, this means that these polymers possess linear flexible chain. It is concluded that [Rh(nbd)Cl] _2/Et_3N was more suitable for the synthesis of the cylindrical polymer brush, poly-PLLA with high molecular weight. The analyses of the CD spectra indicated that poly-PLLA possesses a predominantly one-handed helical conformation, temperature and solvents had significant influences on the helical structure of poly-PLLA.