Department of Physics, The College of Wooster, Wooster, Ohio 44691, United States.
Langmuir. 2011 Mar 1;27(5):1707-12. doi: 10.1021/la104350g. Epub 2011 Jan 18.
The reverse Pluronic triblock copolymer 17R4 is formed from poly(propylene oxide) (PPO) and poly(ethylene oxide) (PEO): PPO(14)-PEO(24)-PPO(14), where the subscripts denote the number of monomers in each block. In water, 17R4 shows both a transition to aggregated micellar species at lower temperatures and a separation into copolymer-rich and copolymer-poor liquid phases at higher temperatures. For 17R4 in H(2)O and in D(2)O, we have determined (1) the phase boundaries corresponding to the micellization line, (2) the cloud point curves marking the onset of phase separation at various compositions, and (3) the coexistence curves for the phase separation (the compositions of coexisting phases). In both H(2)O and in D(2)O, 17R4 exhibits coexistence curves with lower consolute temperatures and compositions that differ from the minima in the cloud point curves; we take this as an indication of the polydispersity of the micellar species. The coexistence curves for compositions near the critical composition are described well by an Ising model. For 17R4 in both H(2)O and D(2)O, the critical composition is 0.22 ± 0.01 in volume fraction. The critical temperatures differ: 44.8 °C in H(2)O and 43.6 °C in D(2)O. The cloud point curve for the 17R4/D(2)O is as much as 9 °C lower than in H(2)O.
反向 Pluronic 三嵌段共聚物 17R4 由聚（环氧丙烷）（PPO）和聚（环氧乙烷）（PEO）组成：PPO(14)-PEO(24)-PPO(14)，其中下标表示每个嵌段中的单体数。在水中，17R4 在较低温度下表现出向聚集胶束物种的转变，在较高温度下表现出向共聚物富相和共聚物贫相的分离。对于 17R4 在 H(2)O 和 D(2)O 中的情况，我们已经确定了（1）对应于胶束化线的相界，（2）在各种组成下标记相分离开始的浊点曲线，以及（3）相分离的共存曲线（共存相的组成）。在 H(2)O 和 D(2)O 中，17R4 都表现出具有较低共溶温度和组成的共存曲线，这些组成与浊点曲线中的最小值不同；我们认为这是胶束物种的多分散性的一个指示。在接近临界组成的组成下，共存曲线很好地由 Ising 模型描述。对于 17R4 在 H(2)O 和 D(2)O 中，临界组成在体积分数上分别为 0.22 ± 0.01。临界温度不同：在 H(2)O 中为 44.8°C，在 D(2)O 中为 43.6°C。17R4/D(2)O 的浊点曲线比在 H(2)O 中低 9°C。
