NMR Spectroscopy and MALDI‐TOF MS Characterisation of End‐Functionalised PVP Oligomers Prepared with Different Esters as Chain Transfer Agents

Summary: Ester‐functionalised poly(1‐vinylpyrrolidin‐2‐one) (PVP) oligomers obtained by radical polymerisation in methyl propionate, diethyl malonate and diethyl 2‐methylmalonate were characterised by NMR spectroscopy, and MALDI‐TOF mass spectrometry. The chain‐transfer constants were determined as 5.54 × 10−4, 1.22 × 10−3 and 1.70 × 10−2, respectively, by measuring the variation of the number‐average molecular weight on conversion. These values were compared with those of methyl isobutyrate (1.65 × 10−3) and ethyl lactate (1.03 × 10−2), which had been previously determined. A clear dependence was found on the reactivity of the mobile hydrogen atoms α with the ester group. All of the macromolecules carried a single ester function. Therefore, the re‐initiation step by the CTA‐derived radicals overwhelmingly prevailed over initiation by the primary radicals. MALDI‐TOF mass spectra of broad‐distribution, end‐functionalised PVP oligomers, analysed in an HCCA matrix. a): PVPL; MALDI molecular weights: M ₙ = 3 465; M w = 3 891; polydispersity index = 1.12. b) PVPM; MALDI molecular weights: M ₙ = 2 272; M w = 2 775; polydispersity index = 1.22. magnified image MALDI‐TOF mass spectra of broad‐distribution, end‐functionalised PVP oligomers, analysed in an HCCA matrix. a): PVPL; MALDI molecular weights: M ₙ = 3 465; M w = 3 891; polydispersity index = 1.12. b) PVPM; MALDI molecular weights: M ₙ = 2 272; M w = 2 775; polydispersity index = 1.22.