Optimization of living polymerization through distributed control of a nitroxide radical

An optimal control methodology is applied to the goal of lowering the react ion time while maintaining low polydispersity in living free-radical polyme rization. An illustration using a nitroxide radical profile for living free -radical polymerization of styrene in a plug how reactor is provided. The r eactor designs show that a distributed nitroxide radical Aux along the leng th of the reactor can reduce the reaction rime significantly for a given co nversion. The reduction in residence time comes at the expense of a modest increase in polydispersity. A reference simulation with no optimization sho ws a conversion of 85% after 70 h and a final polydispersity of 1.31. Optim ization of a 2,2,6,6-tetramethyl-1-piperidinyloxy flux results in a convers ion of 90% after only 46 h while the polydispersity rises slightly to 1.42. The majority of the conversion takes place in the first 35 h. The theoreti cal designs, although not proven to be globally optimal, are of high qualit y. (C) 2000 Elsevier Science Ltd. All rights reserved.