Direct observations of three nucleation/growth processes of charge-stabilized dispersion polymerizations with varying water/methanol ratios.
Direct observations of three nucleation/growth processes of charge-stabilized dispersion polymerizations with varying water/methanol ratios.
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DOI：
10.1021/jp102936n
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发表时间：
2010-08
期刊：
影响因子：
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通讯作者：
Fen Zhang;Yuhong Ma;Lianying Liu;Wantai Yang
中科院分区：
文献类型：
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作者：
Fen Zhang;Yuhong Ma;Lianying Liu;Wantai Yang
本文对自行研制的阳离子电荷稳定苯乙烯/水/甲醇分散聚合体系的三种聚合模式进行了观察：（1）水/甲醇（20/80）体系，对应于典型的分散聚合模式，即粒子在溶液相中成核，在粒子相中生长;（2）纯CH（3）OH体系，包括在溶液相中的第一次成核和在该相中形成的小颗粒和聚合物的吸附生长，以及当高分子量共聚物出现在溶液相中时在颗粒相中的第二次成核和生长;和（3）水/甲醇（5/95）体系，在前90分钟期间类似于常规分散聚合模式，随后进行外延生长。有趣的是，亚稳态的成核阶段，包括微小的6-nm的颗粒，它们的聚集体，和聚集的过程中，首次观察到实验。通过定量跟踪三种体系中沉积分子量与成核/生长过程的关系，提出沉积聚合物的分子量必须达到特定的高值才能吸附或捕获单体形成光滑/球形的核或颗粒。
This article presents observations of three polymerization modes of a self-developed cation-charge-stabilized styrene/water/methanol dispersion polymerization system: (1) a water/methanol (20/80) system, corresponding to a typical dispersion polymerization mode where the particle nucleation occurred in the solution phase and growth in the particle phase; (2) a pure CH(3)OH system, including a first nucleation in the solution phase with growth by absorption of the small particles and polymers formed in this phase, and a secondary nucleation with growth in the particle phase, when high molecular weight copolymers appeared in the solution phase; and (3) a water/methanol (5/95) system, similar to the conventional dispersion polymerization mode during the first 90 min, with subsequent epitaxial growth. Interestingly, the metastable state of the nucleation stage, including minuscule 6-nm particles, their aggregates, and the aggregating process, was first observed experimentally. By quantitatively following the relationship of the deposited molecular weight and the nucleation/growth process in the three systems, it was proposed that the molecular weight of the deposited polymer had to reach a specific high value before they could absorb or capture monomer to form smooth/spherical nuclei or particles.