丙烯酰胺在聚乙二醇水溶液中聚合初期的液滴形成与成长过程  

INITIAL DROPLETS FORMATION AND GROWTH PROCESS OF ACRYLAMIDE DURING AQUEOUS TWO-PHASE POLYMERIZATION IN AQUEOUS POLY(ETHYLENE GLYCOL) SOLUTION

作　　者：吕挺[1] 单国荣[1] 

机构地区：[1]化学工程国家重点实验室(浙江大学)浙江大学化工系,杭州310027

出　　处：《高分子学报》2010年第1期39-44,共6页Acta Polymerica Sinica

基　　金：国家自然科学基金(基金号20776125;20876136);教育部新世纪优秀人才支持计划(项目号NCET-05-0512)资助项目

摘　　要：用动态激光光散射(DLS)在线观测了丙烯酰胺(AM)在聚乙二醇(PEG)水溶液中聚合初期液滴的出现、生长及聚并过程,考察了PEG分子量和浓度对聚合初期液滴尺寸的影响;用透射电镜(TEM)对聚合初期液滴形态的演变进行了观察,发现与DLS结果能很好吻合.用分光光度计对聚合体系分相点进行确定,采用溴化法测定了聚合体系临界分相时的转化率.随PEG分子量或浓度的升高,临界分相转化率逐渐减小;随温度的升高,临界分相转化率先减小后增大,在50℃左右出现最小值.用凝胶渗透色谱(GPC)对聚合体系临界分相时聚丙烯酰胺(PAM)的分子量进行了研究,变化趋势与临界分相转化率的变化一致.在上述基础上,提出了AM在PEG水溶液中聚合初期的液滴形成、成长机理.In order to explore the droplet formation process of the aqueous two-phase polymerization of acrylamide（AM） in aqueous poly（ethylene glycol）（PEG） solution,dynamic light scattering（DLS） was employed to investigate the appearance,the size and size distribution of droplets in the initial stage of polymerization.The effects of PEG molecular weight and concentration on the droplets size and distribution were studied.It was found that the droplets stability in aqueous PEG solution decreased,and the droplets aggregated with each other to form larger and more uniform droplets with decreasing PEG molecular weight or PEG concentration.The morphology of the droplets rich in polyacrylamide（PAM） was observed with transmission electron microscopy（TEM）.The droplets shape in the initial stage of polymerization is spherical but polydisperse.However,some oval droplets formed in the product,while the conversion was still very low,which indicated some coalescence of droplets in this stage.As the polymerization proceeds,the droplet size increased rapidly and the size distribution of droplets become uniform.These results were well in agreement with the DLS results.With using the spectrophotometer,the phase separation point was determined where the transparence of reaction solution declined suddenly.The effect of various parameters on the critical conversion of phase separation was measured by bromating method.It decreased with the increase of PEG molecular weight or PEG concentration.With raising temperature from 30℃ to 70℃,the critical conversion decreased at first,and then turned to increase when the temperature was at about 50℃.The critical molecular weight was also systemically investigated by gel permeation chromatogram（GPC）.It could be seen that the evolution of critical molecular weight corresponded well with that of critical conversion at various reaction conditions.On the basis of above mentioned results,an initial droplet formation and growth mechanism of AM aqueous two-phase polymerization

关 键 词：丙烯酰胺 双水相聚合 临界分相转化率 临界分子量 

分 类 号：O631.3[理学—高分子化学]