单体结构和聚合条件对大体积乙烯基聚合物旋光性质的影响

INFLUENCE OF CHEMICAL STRUCTURE AND POLYMERIZAION CONDITIONS ON CHIROPTICAL PROPERTIES OF BULKY VINYL POLYMERS

合成了3种手性大体积烯类单体——(+)-4,4″-二[(S)-2-甲基丁氧基]-2′-乙烯基对三联苯(p-BMVT)、(+)-3,3″-二[(S)-2-甲基丁氧基]-2′-乙烯基对三联苯(m-BMVT)和(+)-2,2″-二[(S)-2-甲基丁氧基]-2′-乙烯基对三联苯(o-BMVT),其中后两个为新化合物.系统研究了单体结构对其聚合反应活性以及单体结构和反应条件对所得聚合物旋光性质的影响.p-和m-BMVT在合适的条件下可以顺利地进行自由基聚合,形成某一旋向占优的手性二级结构;手性取代基在单体分子上移动一个共价键的距离导致聚合物的旋光方向相反.单体o-BMVT的合成产率低且不能进行自由基聚合.提高芳烃类或者降低非芳烃类聚合溶剂的极性、升高反应温度、减少单体浓度有利于得到旋光度大的聚合物.

Three chiral bulky vinyl monomers, （ ＋ ）-4,4＂-bis [ （ S）-2-methylbutoxy ]-2＇-vinyl-para-terphenyl （ p- BMVT）, （ ＋ ）-3,3＂-his [ （ S）-2-methylbutoxy]-2＇-vinyl-para-terphenyl （m-BMVT） and （ ＋ ）-2, 2＂-his [ （ S）-2- methylbutoxy]-2＇-vinyl-para-terphenyl （o-BMVT） were synthesized. The later two were new molecules. The dependence of polymerizabilities of monomers on the chemical structures and the dependence of ehiroptical properties of polymers on the chemical structures and reaction conditions were systematically studied, p-BMVT and m-BMVT were readily polymerized by radical mechanism to produce optically active helical polymers. Moving the chiral alkoxy groups on terphenyl by just a distance of one bond length inversed the direction of optical rotation, o-BMVT was obtained with quite low yield and couldn＇t undergo radical polymerization. Using polar aromatic solvent and apolar aliphatic solvent, increasing reaction temperature, and reducing monomer concentration favored the formation of polymers with higher specific optical rotation.