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Nucleation process and coil-globule transition of poly(methyl methacrylate in dilute solutions)

聚甲基丙烯酸甲酯在稀溶液中的成核过程和卷曲球转变

基本信息

批准号：
10640377
负责人：
NAKATA Mitsuo
金额：
$ 0.38万
依托单位：
HOKKAIDO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

Phase separation occurs very slowly for the dilute solutions of poly(methyl methacrylate) (PMMA) in isoamyl acetate (System I) and PMMA in the mixed solvent ter-butyl alcohol + water(2.5 vol%) (System II). Taking advantage of this slow phase separation, the coil-globule transition and the initial stage of phase separation were studied by light scattering measurements, which were carried out in the concentration range from 0.6 x 10ィイD1-4ィエD1 g/cmィイD13ィエD1 to 6.0x10ィイD1-4ィエD1. For the system I with the molecular weight MィイD2wィエD2 x 10ィイD1-6ィエD1 = 2.4 and 4.4, polymer chains contracted to equilibrium sizes in the first, 30 min after quench. For the system II with MィイD2wィエD2 x 10ィイD1-6ィエD1 = 8.4 and 12.2 , polymer chains contracted very slowly and took a few hundred minutes to a few thousand minutes to attain equlilibrium globules. The contraction of polymer chains occurred in a single stage and was represented by a power law. For the system I with MィイD2wィエD2 x 10ィイD1-6ィエD1 = 2.4 and 4.4 and system II with MィイD2wィエD2 x 10ィイD1-6ィエD1 = 1.57, phase separation process was measured in time periods from a few hours to a few days. The obtained light scattering data were analyzed by the Guinier plot, which yielded the weight average molecular weight, <M>ィイD2wィエD2 and z-average square radius <RィイD12ィエD1>ィイD2zィエD2 of clusters of polymer chains. Both the plots of In<M>ィイD2wィエD2 and In<RィイD12ィエD1>ィイD2zィエD2, versus time were represented by straight lines, whose slopes were proportional to the concentration. The slow phase separation was concluded to be due to the the reaction limited cluster aggregation. Since the aggregation of polymer chains stems from the reaction between segments, tho slow chain contraction was also found to be due to the reaction limited aggregation between segments.

聚甲基丙烯酸甲酯 (PMMA) 的乙酸异戊酯稀溶液（系统 I）和 PMMA 的混合溶剂叔丁醇 + 水（2.5 vol%）（系统 II）的相分离发生得非常缓慢。利用这种缓慢的相分离，通过光散射测量研究了线圈-球体转变和相分离的初始阶段，测量浓度范围为0.6 x 10ィイD1-4ィエD1 g/cmィイD13ィエD1至6.0x10ィイD1-4ィエD1。对于分子量 MィイD2wィエD2 x 10ィイD1-6ィエD1 = 2.4 和 4.4 的系统 I，聚合物链在淬火后 30 分钟内首先收缩到平衡尺寸。对于 MィイD2wィエD2 x 10ィイD1-6ィエD1 = 8.4 和 12.2 的系统 II，聚合物链收缩非常缓慢，需要几百分钟到几千分钟才能达到平衡球。聚合物链的收缩发生在一个阶段，并由幂律表示。对于MィイD2wィエD2 x 10ィイD1-6ィエD1 = 2.4和4.4的系统I和MィイD2wィエD2 x 10ィイD1-6ィエD1 = 1.57的系统II，在几小时到几天的时间段内测量相分离过程。通过Guinier图分析获得的光散射数据，得到聚合物链簇的重均分子量、<M>ィイD2wィエD2和z均平方半径<RィイD12ィエD1>ィイD2zエD2。 In<M>ィイD2wィエD2 和 In<RィイD12ィエD1>ィイD2zィエD2 与时间的关系图均由直线表示，其斜率与浓度成正比。缓慢的相分离被认为是由于反应限制了簇聚集。由于聚合物链的聚集源于链段之间的反应，因此缓慢的链收缩也被发现是由于反应限制了链段之间的聚集。