Adolphe Merkle Institute, University of Fribourg, Rte de l'ancienne Papeterie 1, CH-1723 Marly, Switzerland.
Langmuir. 2012 Jul 17;28(28):10381-8. doi: 10.1021/la301191n. Epub 2012 Jul 2.
Steric stabilization of colloids forms a robust mechanism to obtain colloids that are stable in a variety of environments, and that can be used to study the phase behavior of hard or soft spheres. We report the synthesis of sterically stabilized colloids in an aqueous environment using readily dissolvable surfactants, with an unsaturated hydrophobic tail. We synthesized a new surfactant by esterification of a poly(ethylene glycol) (PEG) chain of 4.1 kg/mol with oleic acid, called PEG4OA. The micellization of PEG4OA was characterized by light and neutron scattering, which yielded values for the aggregation number and the overall size that are in excellent agreement with a comparable surfactant with a saturated octadecane chain, Brij 700. We successfully used PEG4OA in the emulsion polymerization of polystyrene colloids. In comparison with the smaller surfactant Tween 80, PEG4OA yielded smaller colloids with radii around 50 nm, and the addition of 1-dodecanethiol reduced the formation of aggregates during the synthesis. A contrast variation study with small angle neutron scattering (SANS) showed that a dense PEG layer was grafted to the colloid surface.
胶体的空间稳定形成了一种强大的机制，可获得在各种环境中稳定的胶体，可用于研究硬球或软球的相行为。我们报告了在水相环境中使用易溶解的表面活性剂合成空间稳定胶体的方法，这些表面活性剂具有不饱和的疏水尾。我们通过将 4.1 kg/mol 的聚乙二醇（PEG）链与油酸酯化合成了一种新的表面活性剂，称为 PEG4OA。PEG4OA 的胶束化通过光散射和中子散射进行了表征，得到的聚集数和整体尺寸与具有饱和十八烷链的可比表面活性剂 Brij 700 非常吻合。我们成功地将 PEG4OA 用于聚苯乙烯胶体的乳液聚合。与较小的表面活性剂 Tween 80 相比，PEG4OA 生成的胶体半径约为 50nm，并且在合成过程中添加 1-十二硫醇可减少聚集物的形成。小角中子散射（SANS）的对比变化研究表明，致密的 PEG 层被接枝到胶体表面。
