ISSN:
1022-1352
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
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.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
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