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Synthesis and ring‐opening polymerization of cyclic diurethanes of AA/BB‐type; characterization of the corresponding polyurethanes
Author(s) -
Schmitz Frank,
Keul Helmut,
Höcker Hartwig
Publication year - 1998
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/(sici)1521-3935(19980101)199:1<39::aid-macp39>3.0.co;2-d
Subject(s) - polymer chemistry , polymerization , polyurethane , gel permeation chromatography , chemistry , ring opening polymerization , molar mass distribution , condensation polymer , polymer , step growth polymerization , organic chemistry
Cyclic diurethanes of AA/BB type 3a–d were prepared starting from the diamines 1,2‐diaminoethane ( 1a ), 1,3‐diaminopropane ( 1b ), 1,3‐diamino‐2,2‐dimethylpropane ( 1c ), 1,4‐diaminobutane ( 1d ) and 2,2‐dimethyltrimethylene bis(chloroformate) ( 2 ) under high dilution conditions. The NMR spectroscopic characterization of the cyclic diurethanes reveals a highly rigid conformation of the diurethane cycles. Upon interfacial polycondensation the starting materials result in polyurethanes 4a—d . Gel‐permeation chromatography (GPC) reveals the multimodal distribution of the polymers: beside high molecular weight material low molecular weight cyclic oligomers are observed in appreciable amount. Ring‐opening polymerization of the diurethanes 3a—c results in cyclic ureas 6a—c and 2,2‐dimethyltrimethylene carbonate (DTC), respectively, oligomers formed from DTC. Ring‐opening polymerization of the cyclic diurethane 3d in the melt or in solution with various nucleophilic initiators results in polyurethane 4d . NMR spectroscopic analysis of polyurethane 4d reveals that beside urethane groups carbonate and urea groups are present, their concentration being dependent on the initiator used and the polymerization conditions applied. The polyurethane 4d obtained by ring‐opening polymerization does not contain cyclic oligomers.