Causse J, Lagerge S, de Menorval L C, Faure S
Laboratoire des Agrégats Moléculaires et Matériaux Inorganiques, C.N.R.S. UMR-5072, Université de Montpellier II, CC 015, Place E. Bataillon, 34095 Montpellier Cedex 05, France.
J Colloid Interface Sci. 2006 Aug 15;300(2):724-34. doi: 10.1016/j.jcis.2006.04.043. Epub 2006 Apr 25.
The solubilization of tributylphosphate (TBP), a polar oil, in various micellar solutions of Pluronic has been investigated by (1)H NMR spectroscopy. Partial phase diagrams of the three components systems (Pluronic-TBP-water) have shown two characteristic temperatures, called CPT and SMT, which control the phase behavior (see Part I); Both temperature depend on the copolymer structure and, interestingly, are directly related to the TBP concentration in the medium. Monophasic microemulsions are observed only when the temperature ranges between the SMT and the CPT. Moreover, the evolution of the CPT with the TBP content clearly indicated the occurrence of a structural change of the microemulsions which allows higher quantities of TBP to be solubilized. In this second part, (1)H NMR studies of TPB/micellar systems have essentially focused on elucidating the nature of the interactions between TBP and micelle, or on the location of the solubilized species, mainly from the dependence of chemical shifts or linewidths on TBP concentration. Especially, the NMR spectra of the microemulsions before and after the structural change have been compared with those obtained for pure solution of Pluronic in D(2)O at different temperatures and in CDCl(3). The analysis of the (1)H NMR chemical shifts suggests a structural transformation of the TBP-Pluronic micelles in the sense of an hydrophobic TBP-PPO core becoming more and more dense as the TBP concentration increases. Especially, (1)H NMR data evidence an evolution of the hydration state of the hydrophobic core following addition of TBP in the micellar solutions. During the addition of TBP, the microemulsion structure turns from spherical swelled micelles to nanodroplets of pure TBP stabilized by the Pluronic (pure nanophase of TBP stabilized by the copolymer). It is shown that the structural change strongly depends on the temperatures (CPT and SMT, see Part I) and on the copolymer structure.
通过核磁共振氢谱（¹H NMR）研究了磷酸三丁酯（TBP，一种极性油）在多种普朗尼克胶束溶液中的增溶作用。三元体系（普朗尼克 - TBP - 水）的部分相图显示出两个特征温度，称为CPT和SMT，它们控制着相行为（见第一部分）；这两个温度均取决于共聚物结构，有趣的是，它们与介质中TBP的浓度直接相关。仅当温度在SMT和CPT之间时才观察到单相微乳液。此外，CPT随TBP含量的变化清楚地表明微乳液发生了结构变化，从而使得能够增溶更多量的TBP。在第二部分中，TPB/胶束体系的¹H NMR研究主要集中在阐明TBP与胶束之间相互作用的本质，或者增溶物质的位置，主要是从化学位移或线宽对TBP浓度的依赖性方面进行研究。特别是，将结构变化前后微乳液的核磁共振谱与在不同温度下普朗尼克在D₂O中的纯溶液以及在CDCl₃中获得的谱图进行了比较。对¹H NMR化学位移的分析表明，随着TBP浓度增加，TBP - 普朗尼克胶束发生了结构转变，即疏水的TBP - PPO核变得越来越致密。特别是，¹H NMR数据证明了在胶束溶液中加入TBP后疏水核的水合状态发生了变化。在加入TBP的过程中，微乳液结构从球形膨胀胶束转变为由普朗尼克稳定的纯TBP纳米液滴（由共聚物稳定的纯TBP纳米相）。结果表明，结构变化强烈依赖于温度（CPT和SMT，见第一部分）和共聚物结构。
