褐藻酸铜配合物膜催化VAc自由基聚合  

VAc Free-Radical Polymerization Catalyzed by Copper Alginate Complex Film

作　　者：程贤甦[1] 苏英草[1] 关怀民[1] 程传煊[2] 

机构地区：[1]福建师范大学高分子研究所,福州350007 [2]福建师范大学化学系,福州350007

出　　处：《Chinese Journal of Chemical Physics》2000年第5期629-636,共8页化学物理学报（英文）

摘　　要：以褐藻酸钠膜浸渍在 15%CuCl2 ·2H2 O水溶液中 4 8h的方法 ,于室温制备了疏水性的褐藻酸铜 (Ⅱ)配位聚合物膜 ,并通过ESR、UV -Vis、IR、XPS和电导率等手段 ,研究此配位催化剂褐藻酸铜 (Ⅱ)配位聚合物膜表面的组成、配位结构和性质 ,得知 1个Cu2 + 是以dsp2 杂化空轨道与褐藻酸 2个链节单元的 2个羧羟基氧及其 2个脱质子带负电荷氧的孤对电子发生配位作用 ,形成低自旋构型的褐藻酸铜 (Ⅱ)配位聚合物 ,中心Cu2 + 的配位数为 4 ,这对于低分子配合物而言 ,其空间构型一般是正方形 ,但在褐藻酸铜 (Ⅱ)配位聚合物中 ,由于褐藻酸分子链的缠绕和卷曲 ,使上述的空间构型被扭曲 ,甚至有些配位体没有到位 ,导致该配位聚合物的中心Cu2 + 存在一些空位中心而具有配位催化活性 ,因此 ,HSO3 - 能按配位催化机理产生初级自由基氢 ,使醋酸乙烯酯 (VAc)按自由基加聚反应历程进行聚合 ,这有别于CuCl2 -Na2 SO3 -H2 O氧化还原引发聚合体系。测定VAc在本体系和室温、pH=7条件下聚合的诱导期为 90s ,反应时间 2 4h。聚醋酸乙烯酯 (PVAc)得率 82 % ,mw=1.0 2× 10 6,mn=2 .2 7× 10 5,mw/mn=4 .4 9。A hydrophobic Cu(Ⅱ)-alginate coordination polymer film was prepared by soaking sodium alginate film into 15% CuCl 2·2H 2O aqueous solution at room temperature over 24 h. The composition, structure and property of Cu(Ⅱ)-alginate as coordination catalyst were studied by ESR, UV-Vis, IR, XPS and electric conductivity methods. It was shown that low spin Cu(Ⅱ) complex was formed as a result of the acceptance of dsp 2 hydrid orbitals with nonpair electrons transferred from oxygen atoms of two carbonyl hydroxyl groups and negative charge oxygen atoms of two deprotonated carbonyl hydroxyl groups of two alginate chains. The coordination number of center Cu(Ⅱ) in Cu(Ⅱ)-alginate is four. It can be concluded that the vacant site and catalysis active resulted from the distorted tetragonal configuration that was caused by wine and crimp of alginate molecular chain. HSO 3 - could produce primary free-radical hydrogen by coordination catalysis mechanism, and VAc conducted polymerization by free-radical mechanism, which is different from that of polymerization initiated by CuCl 2-Na 2SO 3-H 2O oxidation-reduction system. The induction period for VAc polymerization is 90 s and yield is 82%, m w, m n and m w/m n of PVAc obtained is 1.02×10 6 , 2.27×10 5 and 4.49, respectively.

关 键 词：催化 醋酸乙烯醋 自由基聚合 褐藻酸铜配合物膜 

分 类 号：O631[理学—高分子化学]