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On the Radiation‐Induced Polymerisation of 2,3‐Dihydropyran
Author(s) -
Naumov Sergej,
Janovský Igor,
Knolle Wolfgang,
Mehnert Reiner
Publication year - 2004
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.200400049
Subject(s) - cationic polymerization , chemistry , polymerization , polymer chemistry , dimer , photochemistry , carbocation , polymer , radical polymerization , radical ion , electron paramagnetic resonance , photopolymer , organic chemistry , ion , physics , nuclear magnetic resonance
Summary: Concentrated (5 mol‐%) solutions of 2,3‐dihydropyran in CFCl 2 CF 2 Cl matrix were irradiated at 77 K and several intermediates – radical cation, dimer radical cation, dihydropyryl radical and a trapped polymer radical – were observed by low‐temperature EPR spectroscopy. The irradiated solutions yielded after melting a polymeric product, which was characterised by IR spectroscopy and GPC. The polydisperse polymer is assumed to be formed by a cationic process initiated by a dimer carbocation. The polymerization proceeds via the ring double bonds, while ring‐opening reaction occurs in a small extent. The free‐radical mechanism via the dihydropyryl radical leads to low molecular weight oligomers only. The quantum chemical calculations support the interpretation of the experimental results.