| Summary: | 碩士 === 國立成功大學 === 化學工程研究所 === 83 === Polyurethanes containing coumarin dimer component were prepared
by polyaddition of diisocyanates with anti 7-hydroxy
(-4-methyl) coumarin dimers, which were synthesized by
photodimerization under 350 nm UV light. Polymerization
conditions and properties of the polyurethanes were first
investigated, then their reversible photocleavage were also
studied. In order to control the structure of coumarin dimer
chrompohores in main chain, 7-acetoxy(-4-methyl) coumarins were
first prepared and then photodimer- ized under 350 nm UV light
to give anti head-to-head 7-acetoxycoumarin dimer and anti head-
to- tail 7-acetoxy-4-methylcoumarin dimer . After hydrolyzing
under acidic conditions to (4-methyl)umbrelliferone
,respectively, they were polymerized with aliphatic and
aromatic diisocyanates in an aprotic solvent to give the
polyurethanes. The polymerization condition, viscosity, and
solution property of these two polyurethanes were investigated
and compared in detail. Then the polyurethanes were
photocleavaged by 254 nm UV light to study its asymmetric
photolytic behaviors. Reversible photodimerization of
photocleavaged compounds were also investigated under 350 nm UV
light.
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