β－二酮或β－三酮对铈（Ⅳ）盐引发烯类单体聚合的影响

Effect of β-Diketone andβ-Triketone on Vinyl Polymerization Initiated by Ceric Salt

研究了β－二酮或β－三酮（如：３－苄基乙酰丙酮、苯甲酰基丙酮、二苯甲酰基甲烷及３－苯甲酰基乙酰丙酮）对铈（Ⅳ）盐引发丙烯酰胺聚合的促进作用，测定了聚合反应速度及表现活化能，表明铈（Ⅳ）盐／β－二酮或β－三酮可组成活性很高的氧化还原体系；采用自旋捕捉技术及ＥＳＲ谱研究了体系的初级自由基结构；通过ＦＴＩＲ光谱端基分析检测到这类体系引发丙烯腈所得聚合物端基有β－二酮结构。以此为基础，提出了这类体系引发烯类单体聚合的机理。

The effect of β-diketone and β-triketone,such as 3-benzy1-2,4-pentanedione(BzyAcAc),benzoylacetone(BzAc),dibenzoylmethane(DBzM) and 3-benzoy1-2,4-pentanedione(BzAcAc),on polymerization of acrylamide(AAM) initiated by ceric ion was investigated.The determination of polymerization rate and overall activation energy showed that theseβ-diketones(orβ-triketone) coupled with ceric ion can form very active redox systems.The structures of free radicals resulting from these systems were monitored by radical trapping technique and ESR spectra,and the β-diketone fragments in polyacrylonitrile initiated by above mentioned systems were detected by means of FTIR spectra end group analysis.The initiating mechanisms of ceric ion/β-diketone(orβ-triketone) systems were proposed.