Synthesis of semitelechelic poly[N-(2-hydroxypropyl)methacryl-amide] 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-mercaptopropionate (MMP) and 2-mercaptoethylamine (MEA) were used as chain transfer agents and 2,2′-azobisisobutyronitrile (AIBN) was used as the initiator. Semitelechelic (ST) polymers produced under various reaction conditions were analyzed by Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) and size exclusion chromatography (SEC). The molecular weight of the ST polymers was regulated by the initial molar ratio of chain transfer agent to HPMA. The free radicals formed by the decomposition of AIBN initiated a fraction of polymer chains; such chains were not terminated in a functional group. The amount of these polymer chains depended on the concentration and efficiency of the chain transfer agent, concentration of AIBN, and conversion. Decreasing the concentration of AIBN and increasing the concentration of the chain transfer agent reduced the formation of nonfunctionalized polymer chains.