Pseudoliving polymerization

Nearly at the same time, Johnson and Young reported a similar system for the polymerization of -butyl vinyl ether with iodine, and called the process a pseudoliving polymerization [55], Also, Pepper suggested that the active centers in polystyrene derived from perchloric acid might have a long lifetime at a very low temperature [32,50], and later obtained block copolymers of styrene with /< r/-butylazyridine by a sequential polymerization from the perchlorate-initiated polystyrene end [56]. 

A study of the polymerization kinetics of methyl methacrylate, in the presence of PBN, and of molecular-mass properties of the obtained polymers shows that the systems react by the pseudoliving mechanism (699). In the first stages of the polymerization process, PBN reacts with oligomeric radicals, forming stable nitroxyl radical-spin adducts A-, see Scheme 2.207. 

Research over the past 30 years has produced a large number of ROMP polymers, and virtually all of these polymerizations have been reviewed elsewhere. The most recent work has revolved about the living or pseudoliving nature of ROMP polymerization, and a few words regarding this chemistry are worth mentioning here. 

The block copolymer preparative techniques reviewed in this report include sequential addition to macroanions, "pseudoliving" carbenium ion systems, used of coordination catalysts, coupling of polymer termini, and various preparations employing free radical polymerization. The review covers 133 papers and patents. 

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