NMR spectroscopy and MALDI-TOF MS characterisation of end-functionalised PVP oligomers prepared with different esters as chain transfer agents |
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Authors: | Ranucci Elisabetta Ferruti Paolo Annunziata Rita Gerges Irini Spinelli Giuseppe |
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Institution: | Department of Organic and Industrial Chemistry, University of Milano, 20133 Milano, Italy. elisabetta.ranucci@unimi.it |
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Abstract: | 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 x 10(-4), 1.22 x 10(-3) and 1.70 x 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 x 10(-3)) and ethyl lactate (1.03 x 10(-2)), which had been previously determined. A clear dependence was found on the reactivity of the mobile hydrogen atoms alpha 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. |
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Keywords: | chain‐transfer radical polymerization functionalization of polymers hydrophilic polymers 1D and 2D NMR spectroscopy PVP functional oligomers |
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