Greyling Guilaume, Pasch Harald
Department of Chemistry and Polymer Science, University of Stellenbosch, Private Bag X1, 7602 Stellenbosch, South Africa.
Department of Chemistry and Polymer Science, University of Stellenbosch, Private Bag X1, 7602 Stellenbosch, South Africa.
J Chromatogr A. 2015 Oct 2;1414:163-72. doi: 10.1016/j.chroma.2015.08.023. Epub 2015 Aug 15.
Poly(methyl methacrylate)-polystyrene (PMMA-PS) micelles with isotactic and syndiotactic coronas are prepared in acetonitrile and subjected to thermal field-flow fractionation (ThFFF) analysis at various conditions of increasing temperature gradients. It is shown for the first time that multidetector ThFFF provides comprehensive information on important micelle characteristics such as size (Dh), shape (Rg/Rh), aggregation number (Z), thermal diffusion (DT) and Soret coefficients (ST) as a function of temperature from a single injection. Moreover, it is found that micelles exhibit a unique decreasing trend in DT as a function of temperature which is independent of the tacticity of the corona and the micelle preparation method used. It is also demonstrated that ThFFF can monitor micelle to vesicle transitions as a function of temperature. In addition to ThFFF, it is found from DLS analysis that the tacticity of the corona influences the critical micelle concentration and the magnitude to which micelles expand/contract with temperature. The tacticity does not, however, influence the critical micelle temperature. Furthermore, the separation of micelles based on the tacticity of the corona highlight the unique capabilities of ThFFF.
在乙腈中制备了具有全同立构和间同立构冠层的聚（甲基丙烯酸甲酯）-聚苯乙烯（PMMA-PS）胶束，并在温度梯度不断增加的各种条件下进行热场流分级（ThFFF）分析。首次表明，多检测器ThFFF从单次进样中提供了关于重要胶束特性的全面信息，如尺寸（Dh）、形状（Rg/Rh）、聚集数（Z）、热扩散（DT）和索雷特系数（ST）随温度的变化。此外，发现胶束的DT随温度呈现独特的下降趋势，这与冠层的立构规整度和所用的胶束制备方法无关。还证明了ThFFF可以监测胶束向囊泡的转变随温度的变化。除了ThFFF，从动态光散射（DLS）分析中发现，冠层的立构规整度影响临界胶束浓度以及胶束随温度膨胀/收缩的程度。然而，立构规整度并不影响临界胶束温度。此外，基于冠层立构规整度对胶束的分离突出了ThFFF的独特能力。
