Dynamics of PEO–PPO–PEO triblock copolymer in aqueous solutions investigated by internal friction
Dynamics of PEO–PPO–PEO triblock copolymer in aqueous solutions investigated by internal friction
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DOI：
10.1088/0953-8984/19/46/466102
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发表时间：
2007-10
期刊：
影响因子：
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通讯作者：
X. B. Wu;Z. G. Zhu;S. Shang;Q. L. Xu;J. Shui;G. Zhang
中科院分区：
文献类型：
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作者：
X. B. Wu;Z. G. Zhu;S. Shang;Q. L. Xu;J. Shui;G. Zhang
本文用倒置管法和内耗法研究了聚氧化乙烯-嵌段-聚氧化丙烯-嵌段-聚氧化乙烯（PEO-PPO-PEO）在水溶液中聚合物浓度范围为10.0- 45.0wt%的动力学。在α ≤ 31.0wt%时，观察到两个具有一级相变特征的内耗峰，对应于不透明的液-液相变和相分离。不透明的液-液转变是由于胶束形状的球-棒转变，相分离是由于核-壳结构的破坏。在α ≥ 32.0wt%时，除了与相分离相关的内耗峰外，还观察到另外两个峰，其分别对应于溶液-凝胶（液晶-晶体）转变和凝胶-溶液（晶体-液体）转变。前者是由于胶束结晶，而后者是球形胶束在高温下融合成蠕虫状或棒状胶束的结果。
The dynamics of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (PEO–PPO–PEO) in aqueous solutions in the range of the polymer concentration ϕ = 10.0–45.0 wt% has been investigated by the tube inversion method and the internal friction technique. At ϕ≤31.0 wt%, two internal friction peaks are observed with the characteristics of the first-order phase transition, corresponding to the opaque liquid-to-liquid transition and the phase separation. The opaque liquid-to-liquid transition is due to the sphere-to-rod transition in shape of the micelles, and the phase separation is caused by the destruction of core–shell structure. At ϕ≥32.0 wt%, besides the internal friction peak associated with phase separation, two other peaks are observed, which correspond to the solution-to-gel (liquid-to-crystal) transition and gel-to-solution (crystal-to-liquid) transition, respectively. The former is due to the micelle crystallization, whereas the latter is the result of spherical micelles fusing into wormlike or rodlike micelles at elevated temperatures.