Thermal degradation of polystyrene produced by nitroxide-controlled radical polymerization

Although the controlled free radical polymerization brings great advantages , a knowledge of the thermal stability of the products is important for ind ustrial processes. For polystyrene prepared by nitroxide-controlled free ra dical polymerization (macroinitiator PS-N), a first step of mass loss takes place in thermogravimetric analysis (TGA) at temperatures between 180 and 280 degreesC. The temperatures of the first step and the value of the first step mass loss are dependent on the molecular weight and the terminator co ncentration. Detailed stepwise pyrolysis leads to the assumption that there are two parallel reactions for terminator removal. The results of stepwise pyrolysis show the scission of the polystyrene-nitroxide (PS-ONR) bond fol lowed by a weak depolymerization proceed from a secondary macroradical as o ne of the reactions at lower temperatures. With increasing temperature the contribution of the homolysis of the PSO-NR bond rises. (C) 2001 Elsevier S cience B.V. All rights reserved.