Conformational behaviors of syndiotactic polystyrene in chloroform revealed by intrinsic fluorescence technique

Abstract

Conformational behaviors of syndiotactic polystyrene (sPS) in chloroform were investigated by detecting its concentration dependence of intrinsic fluorescence in the range from 25 to −62 °C. For the dimer emission, the coexistence of T-shaped configuration with sandwich configuration was observed and the contribution of sandwich configuration increases with increasing sPS concentration in the system. In addition, three conformations are observed in sPS/CHCl 3 systems: (I) coil phase; (II) coil-to-helix transformation; (III) helix-to-network transformation. The conformational ordering of polymer chain in super dilute sPS/CHCl 3 systems during isothermal process indicated that micro-gel formed when the concentration was higher than 0.2 g L −1, and single helix formed at 0.09 ∼ 0.2 g L −1 proceeds through a unimolecular or self-organization mechanism and no helical aggregates were found. The helix was formed by clustering of several chain segments when the polymer concentration was below 0.09 g L −1. Moreover, a model was proposed to describe the elasticity of sPS/CHCl 3 systems near and beyond the critical percolation concentration.