Synthesis and characterization of a chiral copoly(ether sulfone) with high molecular weight

A series of chiral poly(ether sulfone)s containing (S)-binaphthyl unit were synthesized via nucleophilic substitution polycondensation. The as-synthesized polymers were characterized by NMR. The molecular weights of these polymers were calculated by viscosity and gel permeation chromatography. The thermal stability was measured by TGA. The optical activities of the polymers were studied by circular dichroism and optical rotation. It was found that introducing more reactive 2,2′-biphenol monomer to partly substitute the binaphthol monomer could increase the molecular weight of the polymer from 4.1 × 104 to 9.8 × 104 g mol−1. Meanwhile, the thermal stability increased and the decomposition temperature rose from 447 to 518 °C, with the optical activity of the polymer well preserved. However, the value of the specific optical rotation decreased with increasing biphenol to binaphthol molar ratio. In addition, the optical rotation direction of the polymer was contrary to that of the pristine binaphthol monomer, which indicated that the chiral polymers formed a secondary structure. © 2013 Society of Chemical Industry