Structure and properties of ultra-high molecular weight bisphenol a polycarbonate synthesized by solid-state polymerization in amorphous microlayers

The structure and properties of ultrahigh molecular weight polycarbonate synthesized by solid-state polymerization in micro-layers (SSP_m) are reported. A low molecular weight prepolymer derived from the melt transesterification of bisphenol A and diphenyl carbonate as a starting material was polymerized to highly amorphous and transparent polycarbonate of molecular weight larger than 300,000 g mol^-1 in the micro-layers of thickness from 50 nm to 20 μm. It was observed that when the polymerization time in micro-layers was extended beyond conventional reaction time, insoluble polymer fraction increased up to 95%. Through the analysis of both soluble and insoluble polymer fractions of the high molecular weight polycarbonate by ¹H NMR spectroscopy and pyrolysis-gas chromatography mass spectrometry (Py-GC/MS), branches and partially crosslinked structures have been identified. The thermal, mechanical and rheological properties of the ultra-high molecular weight nonlinear polycarbonates synthesized in this study have been measured by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and rheometry. The nonlinear chain structures of the polymer have been found to affect the polymer's thermal stability, mechanical strength, shear thinning effect, and elastic properties.