Departamento de Física de la Materia Condensada, Facultad de Física, Universidad de Santiago de Compostela, Spain.
J Colloid Interface Sci. 2011 Sep 1;361(1):154-8. doi: 10.1016/j.jcis.2011.05.059. Epub 2011 May 24.
We have used pyrene fluorescence spectroscopy and isothermal titration calorimetry (ITC) to investigate the effect of hydrophobic-block length on values of the critical micelle concentration (cmc) for aqueous solutions of triblock poly(butylene oxide)-poly(ethylene oxide)-poly(butylene oxide) block copolymers (B(n)E(m)B(n), where m and n denote the respective block lengths) with hydrophobic block lengths in the range n=12-21. Combined with results from previous work on B(n)E(m)B(n) copolymers with shorter B blocks, plots of log(10)(cmc) (cmc in molar units and reduced to a common E-block length) against total number of B units (n(t)=n for diblock or n(t)=2n for triblock copolymers) display transitions in the slopes of the two plots, which indicate changes in the micellisation equilibrium. These occur at values of n(t)which can be assigned to the onset and completion of collapse of the hydrophobic B blocks, an effect not previously observed for reverse triblock copolymers. The results are compared with related data for diblock E(m)B(n) copolymers.
我们使用芘荧光光谱法和等温热滴定法（ITC）研究了疏水嵌段长度对一系列三嵌段聚（氧化丁烯）-聚（氧化乙烯）-聚（氧化丁烯）嵌段共聚物（B(n)E(m)B(n)，其中 m 和 n 分别表示各自的嵌段长度）在水中的临界胶束浓度（cmc）值的影响，这些共聚物的疏水嵌段长度范围为 n=12-21。结合之前对具有较短 B 嵌段的 B(n)E(m)B(n)共聚物的研究结果，以摩尔单位表示的 cmc（cmc 被还原到共同的 E 嵌段长度）的对数（10）（cmc 与 B 单元总数（n(t)=n 对于二嵌段或 n(t)=2n 对于三嵌段共聚物）的关系图显示出两条曲线斜率的转变，这表明胶束化平衡发生了变化。这些转变发生在 n(t)的值，可以归因于疏水 B 嵌段的展开和崩溃的开始和完成，这是以前在反向三嵌段共聚物中未观察到的效应。结果与相关的二嵌段 E(m)B(n)共聚物数据进行了比较。
