کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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5183600 | 1381023 | 2012 | 8 صفحه PDF | دانلود رایگان |
A novel polyurethane was synthesized, which consisted of isophorone diisocyanate, polyethylene glycol and photo-reversible moiety 5,7-bis(2-hydroxyethoxy)-4-methylcoumarin. By taking advantage of reversible photodimerization and photocleavage habit of coumarin, the polyurethane can be repeatedly crosslinked and de-crosslinked under successive UV irradiations at 350 and 254Â nm. More importantly, damages in crosslinked version of the polyurethane can be re-bonded through chain reconnection on fracture surfaces resulting from the photochemical reactions, as characterized by mechanical strength restoration tests. Compared to the previous proof-of-concept trial with monohydroxyl coumarin derivatives as the photosensitive groups, the application of dihydroxyl coumarin derivatives in the present work prevented the undesirable gelation during synthesis and enabled properties-oriented structure adjustment of polymerization products. Besides, structure-performance relationship study of the polyurethane revealed that rubbery domains resulting from microphase separation were necessary for the photo-remending with high efficiency.
Journal: Polymer - Volume 53, Issue 13, 7 June 2012, Pages 2691-2698