(749b) Pseudo-Solid State Polymerization In Amorphous Polymer Micro-Layers: A Novel Route to Produce Ultra-High Molecular Weight Polycarbonate

A novel polymerization technique is presented to produce ultra-high molecular weight bisphenol A polycarbonate via step-growth polymerization in micro-layers using low molecular weight polymer precursors produced by melt polycondensation of bisphenol A and diphenyl carbonate. The polymerization is carried out at low pressures and at temperatures close but below the polymer melting point to ensure the reaction proceeds in amorphous state. It was found that the polymerization rate is much faster than in a conventional solid-state polymerization using pre-crystallized prepolymer particles. Transparent polycarbonates of molecular weights as high as 700,000 Da were obtained. Since the reacting polymer micro-layers are neither in the solid state nor in the melt phase, the proposed polymerization is called pseudo-solid state polymerization (p-SSP). The relatively high mobility of polymer chains in the amorphous state, the efficient removal of the condensation by product (i.e., phenol) from the confined geometry, the free radical-induced reactions via thermal decomposition of the residual casting solvent or Fries rearrangement are hypothesized to be the main responsible for the departure of the proposed polymerization technique from the conventional solid state polymerization. Experimental and theoretical investigations to elucidate the key mechanisms governing the p-SSP in amorphous polymer micro-layers will be presented at the meeting.