Applications and novel syntheses of arborescent graft copolymers

Abstract

Arborescent polymers were investigated as melt processing additives for commercial polymers. The branched polymers were blended with linear polystyrene (PS) or poly(methyl methacrylate) (RMMA), and the melt viscosity of the blends was monitored as a function of temperature. Arborescent polystyrene with a low branching functionality, when blended with PS, yielded an increase in melt viscosity at high temperatures. The enhancement was proportional to the amount of branched polymer added. For a PMMA matrix, however, the arborescent polystyrene additive led to a 2- to 3-fold decrease in melt viscosity in the temperature range studied. Arborescent copolymers containing polyisoprene segments of different lengths were also investigated. Blends of PMMA and the polyisoprene copolymers (1-10% w/w) with short branches displayed a decrease in melt viscosity up to 10-fold over the temperature range examined.

The second goal of the research concerned the synthesis of arborescent graft copolymers using anionic ring opening polymerization techniques. These copolymers incorporated a polystyrene core and either polydimethylsiloxane (PDMS) or polycaprolactone side chains. The graft copolymers were obtained by a grafting from method using hydroxyl-functionalized polystyrene cores to initiate the polymerization of hexamethylcyclotrisiloxane (D3) or e-caprolactone.