FUNDAMENTAL-STUDIES OF GRAFTING REACTIONS IN FREE-RADICAL COPOLYMERIZATION .1. A DETAILED KINETIC-MODEL FOR SOLUTION POLYMERIZATION

Graft site initiation occurs by primary radical and/or polymeric radic al attack on the backbone polymer. The controlling mechanism is determ ined by the structure of the backbone and the activity of the free rad icals. The efficiency of incorporating monomer into the graft chains d epends upon the graft site initiation mechanism and the mode of polyme r chain termination (recombination or disproportionation). A kinetic a nalysis results a series of uniquely different expressions describing the graft efficiency, phi, corresponding to different combinations of graft site initiation and chain termination mechanisms. The dependency of phi upon monomer, initiator, and backbone concentrations is differ ent from case to case. The complete kinetic model is capable of predic ting reaction rate, graft efficiency, graft frequency, graft ratio, an d molecular weight averages and distributions. Simulations are provide d to compare predicted results with experimental data for two differen t systems which show contrasting mechanisms of graft site initiation a nd mode of termination. (C) 1995 John Wiley & Sons, Inc.