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Photolysis of segmented polyurethanes. The role of hard‐segment content and hydrogen bonding
Author(s) -
Hoyle Charles E.,
Kim KyuJun,
No Y. G.,
Nelson G. L.
Publication year - 1987
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1987.070340227
Subject(s) - photodegradation , polyurethane , hydrogen bond , photodissociation , polymer , decomposition , materials science , polymer chemistry , photochemistry , chemical engineering , chemistry , molecule , composite material , organic chemistry , photocatalysis , catalysis , engineering
The photodegradation of segmented polyurethanes based on methylene 4, 4′‐diphenyldiisocyanate (MDI) is shown to be dependent on the physical structure of the polymer. As the hard segment content of the polyurethane is increased, the photodegradation efficiency is lowered. In particular, the extent of the photolytic decomposition is inversely dependent on the degree of hydrogen bonding in the aryl carbamate groups in the polyurethane backbone. Utilizing appropriate model compounds for comparison, the formation of the ortho photo‐Fries rearrangement product, as detected by fluorescene spectroscopy, is also shown to be dependent onthe degree of hydrogen bonding. In general, the restrictive mobility imposed by hydrogen bonding is a critical factor which must be considered in the photochemistry of segmented polyurethanes.