New oligomers of N‐vinyl‐2‐pyrrolidinone functionalized at one end with either ester or lactone functions were obtained by radical polymerization in the presence of different ester (methyl isobutyrate and methyl phenylacetate) and lactone (ε‐caprolactone, δ‐valerolactone and γ‐butyrolactone) compounds as chain transfer agents. The oligomeric samples obtained were characterized in terms of molecular weight and molecular weight distribution by means of analytical size exclusion chromatography (SEC), using purposely synthesized poly(N‐vinyl‐2‐pyrrolidinone) standards. The chain transfer constant CT of either methyl isobutyrate, δ‐valerolactone, or γ‐butyrolactone towards N‐vinyl‐2‐pyrrolidinone were determined with the help of the known cumulative number‐average degree of polymerization Xn and monomer conversion Yt of the samples during the reaction.
Polymethacrylonitrile (PMAN) was prepared by bulk, solution and precipitation polymerization. The thermal stability of the polymer, which is affected by the structure of the chain end groups, was studied by non-isothermal thermogravimetry (TG). On the basis of the differential TG curves of samples prepared by polymerization in the presence of chlorinated solvents, it may be concluded that, in addition to end-chain and random main chain scission initiated depolymerization, hydrogen chloride evolution also occurs during the thermal degradation of PMAN.
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