Synthesis of semitelechelic poly [N-(2-hydroxypropyl) methacrylamide] by radical polymerization in the presence of alkyl mercaptans

The free radical polymerization of N-(2-hydroxylpropyl)methacrylamide (HPMA ) in the presence of chain transfer agents was studied. Methyl 3-mercaptopr opionate (MMP) and 2-mercaptoethylamine (MEA) were used as chain transfer a gents and 2,2'-azobisisobutyronitrile (AIBN) was used as the initiator. Sem itelechelic (ST) polymers produced under various reaction conditions were a nalyzed by Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) and size exclusion chromatography (SEC). The mo lecular weight of the ST polymers was regulated by the initial molar ratio of chain transfer agent to HPMA. The free radicals formed by the decomposit ion of AIBN initiated a fraction of polymer chains; such chains were not te rminated in a functional group. The amount of these polymer chains depended on the concentration and efficiency of the chain transfer agent, concentra tion of AIBN, and conversion. Decreasing the concentration of AIBN and incr easing the concentration of the chain transfer agent reduced the formation of nonfunctionalized polymer chains.