双官能及多官能引发剂引发苯乙烯、丙烯酸酯原子转移自由基聚合研究

【作者】 刘海涛；

【导师】 焦书科； 傅志峰；

【作者基本信息】 北京化工大学 ， 材料学， 2000， 硕士

【摘要】 本论文提出一种新型ATRP双官能团引发剂(如α，α-二溴化苄、α，α-二溴乙酸乙酯)，并用聚合反应速度法、GPC法、核磁分析法进行双官能度的验证，并通过两步聚合合成以聚丙烯酸酯为中间嵌段、苯乙烯或甲基丙烯酸甲酯为两端嵌段的ABA型三嵌段共聚物。 分别以1-苯基溴乙烷、α，α-二溴化苄为引发剂进行了苯乙烯的本体聚合及N，N-二甲基甲酰胺(DMF)参与的溶液聚合，所得的聚苯乙烯分子量实测值与理论值接近，分子量分布较窄(Mw／Mn＜1.4)，-Ln(1-X)随反应时间t线性增加，聚合的可控程度较好，证明α，α-二溴化苄为ATRP有效的引发剂。但由于两体系各组分浓度不同，α，α-二溴化苄引发的苯乙烯聚合反应速度并不是1-苯基溴乙烷为引发剂时的两倍。采用1-苯基溴乙烷／α，α-二溴化苄混合引发剂进行苯乙烯的ATRP反应时，所得聚苯乙烯的GPC谱图为双峰，分子量相差一倍，初步证明了α，α-二溴化苄引发苯乙烯ATRP反应时是双官能引发剂，并用~1H-NMR对聚合物结构进行分析，进一步证明了α，α-二溴化苄引发苯乙烯ATRP时是双端同时增长的。按同样思路和方法，借助GPC法证明了α，α-二溴乙酸乙酯也是丙烯酸酯ATRP的双官能引发剂。 以α，α-二溴乙酸乙酯／CuBr／bpy为引发体系，在碳酸亚乙酯的参与下合成了窄分子量分布的聚丙烯酸丁酯大分子引发剂，然后，以CuBr或CuCl为催化剂成功地合成了PSt-PBA-PSt三嵌段共聚物。但是合成PMMA-PBA-PMMA时，须用CuCl为催化剂才可得到高的嵌段效率。 本文还用二氯乙酰氯与多元醇进行酯化反应合成了丙烯酸酯多官能引发剂，并对官能度进行了验证。 本论文为以ATRP法制备聚丙烯酸酯为中间嵌段的热塑性弹性体以及星型聚合物的研究奠定了基础。更多还原

【Abstract】 A new type of difunctional initiator (benzyl dibromide, ethyl dibromoacetate) was proposed in this paper and used to synthesize poly (alkyl acrylate) based triblock copolymers such as PSt-PBA-PSt, PMMA-PBA-PMMA.The atom transfer radical polymerization (ATRP) of styrene in bulk and in aqueous solution with dimethylformamide (DMF) was investigated using CuBr/bpy catalytic system with 1-phenylethyl bromide and benzyl a,oc-dibromide as initiator respectively. The polymerization was well controlled. It suggests that 1-phenylethyl bromide and benzyl dibromide are good initiator for ATRP of styrene. Because of different concentration of each component in above systems, it doesn’t show that benzyl a,a-dibromide is a difunctional initiator. When ATRP of styrene was investigated with 1-phenylethyl bromide/benzyl a,a-dibromide mixture as initiator, the GPC chromatogram shows two elution peaks and the molecular weighs of the peaks are approximately in a 2/1 ratio. It suggests that benzyl dibromide is a difunctional initiator of ATRP of styrene. The analysis of end group using 1H-NMR also proves the result above. Similarly, by way of GPC chromatogram we proved that ethyl dibromoacetate is a good difunctional initiator of ATRP of acrylate.In this paper, narrow molecular weight distribution poly (butyl acrylate) difunctional precursors were prepared by ATRP using ethyl dibromoacetate as initiator and CuBr/bpy complex as catalyst, in the present of ethylene carbonate (EC). Then, well-defined PSt-PBA-PSt triblock copolymers were prepared using bromine end capped poly (butyl acrylate) as difunctional initiator, CuCl/bpy or CuBr/bpy as catalyst. But only with CuCl/bpy as catalyst can well-defined PMMA-PBA-PMMA triblock copolymers be prepared using bromine end capped poly (butyl acrylate) as difunctional initiator. In addition, tetrafunctinal and hexafunctional initiators were prepared simply by esterification of chloride dichloroacetyl and confirmed by GPC and 1H-NMR.This work is useful for the preparation of four-armed and six-armed star polymers and TPEs with higher oxidation resistance and oil resistance.更多还原