TEMPO-controlled free radical suspension polymerization

The free radical polymerization controlled by 2,2,6,6-tetramethylpiperidine -N-oxyl (TEMPO) was carried out in a water/oil suspension at 120-135 degree s C. Suspension polymerization is a polymerization reaction with high conve rsion and allows high-molecular-weight polymers to be synthesized. The poly merization was started by a styrene macroinitiator. The block length is det ermined by the level of conversion and the initial macroinitiator concentra tion. A kinetic model is introduced which predicts a drastic reduction of p olymerization time (at ca. 90% conversion a reduction from ca. 20 h to 5-3 h) and improved polydispersity through selective addition of initiator. The agreements between the simulated results and the experimental findings are surprisingly good. From model calculation, the percentage and molar mass d istributions of the dead polymers can also be derived.