Chaibundit Chiraphon, Ricardo Nágila M P S, Costa Flávia de M L L, Yeates Stephen G, Booth Colin
Polymer Science Program, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla, Thailand.
Langmuir. 2007 Aug 28;23(18):9229-36. doi: 10.1021/la701157j. Epub 2007 Aug 3.
The micellization in dilute aqueous solution of Pluronic copolymers P123 (E21P67E21) and F127 (E98P67E98) and mixtures of the two was investigated using static and dynamic light scattering. Gelation of concentrated solutions of the two copolymers and their mixtures was studied using tube inversion and oscillatory rheometry. The two copolymers comicellized to give micelles with narrow size distributions. Clouding temperatures and critical micelle temperatures decreased as the proportion of P123 in the mixture was increased. Micelle association numbers of the mixed micelles lay between the values found for micelles of P123 and F127 alone, whereas micelle radii passed through maximum values in the range 0-50 wt % P123. As judged by the ratio of the thermodynamic to the hydrodynamic radius, the micelle interaction potential changes gradually from soft to hard as the proportion of P123 in the mixture is increased. Regions of cubic and hexagonal (birefringent) gel were defined for concentrated solutions. The high-temperature boundary of the 30 wt % cubic gel decreased monotonically from 90 to 43 degrees C as the proportion of P123 in the mixture was increased from 0 to 100 wt %, whereas the low-temperature boundary was essentially constant at 15 +/- 3 degrees C. Increasing the proportion of P123 in the mixture at 25 degrees C increased the concentration at which the cubic gel was first formed and decreased the concentration at which the hexagonal gel was first formed.
采用静态和动态光散射法研究了泊洛尼克共聚物P123（E21P67E21）和F127（E98P67E98）在稀水溶液中的胶束化行为以及二者的混合物。使用试管倒置法和振荡流变学研究了这两种共聚物及其混合物浓溶液的凝胶化过程。两种共聚物形成混合胶束，其尺寸分布较窄。随着混合物中P123比例的增加，浊点温度和临界胶束温度降低。混合胶束的胶束聚集数介于单独的P123和F127胶束的数值之间，而胶束半径在P123含量为0 - 50 wt%范围内出现最大值。根据热力学半径与流体力学半径的比值判断，随着混合物中P123比例的增加，胶束相互作用势从软逐渐变为硬。确定了浓溶液的立方相和六方相（双折射）凝胶区域。随着混合物中P123的比例从0增加到100 wt%，30 wt%立方相凝胶的高温边界从90℃单调下降至43℃，而低温边界基本恒定在15±3℃。在25℃下增加混合物中P123的比例，会提高立方相凝胶首次形成时的浓度，并降低六方相凝胶首次形成时的浓度。
