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HERO ID
4798227
Reference Type
Journal Article
Title
Synthesis, kinetics of photo-dimerization/photo-cleavage and physical properties of coumarin-containing branched polyurethanes based on polycaprolactones
Author(s)
Seoane Rivero, R; Bilbao Solaguren, P; Gondra Zubieta, K; Peponi, L; Marcos-Fernandez, A
Year
2016
Is Peer Reviewed?
Yes
Journal
Express Polymer Letters
ISSN:
1788-618X
Volume
10
Issue
2
Page Numbers
84-95
DOI
10.3144/expresspolymlett.2016.10
Web of Science Id
WOS:000366128600002
Abstract
A series of coumarin-containing branched polyurethanes based on polycaprolactones, hexamethylene diisocyanate and a monohydroxylated coumarin monomer with 5 and 10% content by weight of coumarin units were successfully prepared. Chain architecture was controlled by combination of polycaprolactone (PCL) triol or tetrol with PCL diol. Terminal coumarin units segregated from the polyurethane matrix as measured by differential scanning calorimetry (DSC). Photo-dimerization with 313 nm lamps presented an anomalous behavior in two steps with high irreversibility at high conversions. Photo-dimerization/photo-cleavage reactions showed an increase in irreversibility with the increase in cycles. It was demonstrated that conversion measured by Raman spectroscopy gave the same results than conversion measured by ultraviolet (UV) spectroscopy. Photo-dimerization produced an elastomeric material with much better mechanical properties than non-irradiated material as a consequence of the crosslinking produced. Photo-cleavage decreased the mechanical properties and repeated photo-dimerization increased mechanical properties again.
Keywords
smart polymers; coumarin; polycaprolactone; polyurethanes
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