The Anionic polymerization of 1,3,5-trimethyl-1,3,5-triphenyl- cyclotrisiloxane

• Main Authors: Tsai,Foo-Jung, 蔡馥嶸
• Other Authors: Yang,Mei-Hui
• Format: Others
• Language: zh-TW
• Published: 1993
• Online Access: http://ndltd.ncl.edu.tw/handle/40329257185510516340

碩士 === 國立臺灣大學 === 化學學系 === 81 === The purpose of this work is to investigate the proper synthetic condition under which narrow distributed linear polymethylphenylsiloxane(PMPS) could be synthesized.The assignments of the methyl groups of PMPS on HNMR spectra were also confirmed. In the preparation of narrow molecular weight distributed PMPS, n-BuLi was used as initiator. It was found that narrow molecular weight distributed homopolymers could be obtained through the bulk process under 200C, however backbiting happened and only 81.4% yielded.In solution polymerization, THF and Toluene were used as solvents. It was found that when THF was used both as solvent and promoter under refluxing, narrowly dispersed PMPS could be obtained with high conversion(99.6%) and least backbiting and without chain transfer. The assignments of the methyl groups in the PMPS on proton NMR spectra was done by according to the polymerization mechanisms and the proton NMR analysis. The three peaks of the structures from high field to down field were assigned to be mm,mr,rr. By using molecular model , we found that the reason of the opposite assignments of the methyl groups in the PMPS and poly(α- methyl styrene) could due to the intramolecular compensation in PMPS.