Preparation and Photoreaction of Polyurethanes Containing Coumarin Dimer Component

• Main Authors: Kong-Hong Chen, 陳冠宏
• Other Authors: Yun Chen
• Format: Others
• Language: zh-TW
• Published: 1995
• Online Access: http://ndltd.ncl.edu.tw/handle/35959160191846025119

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.