Ulama Jeanette, Zackrisson Oskolkova Malin, Bergenholtz Johan
Department of Chemistry and Molecular Biology, University of Gothenburg , SE-41296 Göteborg, Sweden.
J Phys Chem B. 2014 Mar 6;118(9):2582-8. doi: 10.1021/jp500568a. Epub 2014 Feb 25.
Fluorinated core-shell spheres have been synthesized using a novel semibatch emulsion polymerization protocol employing slow feeding of the initiator. The synthesis results in aqueous dispersions of highly monodisperse spheres bearing a well-defined poly(ethylene glycol) graft (PEGylation). Measurements are consistent with the synthesis achieving a high grafting density that moreover consists of a single PEG layer with the polymer significantly elongated beyond its radius of gyration in bulk. The fluorination of the core of the particles confers a low index of refraction such that the particles can be refractive index matched in water through addition of relatively small amounts of a cosolvent, which enables the use of optical and laser-based methods for studies of concentrated systems. The systems exhibit an extreme stability in NaCl solutions, but attractions among particles can be introduced by addition of other salts, in which case aggregation is shown to be reversible. The PEGylated sphere dispersions are expected to be ideally suited as model systems for studies of the effect of PEG-mediated interactions on, for instance, structure, dynamics, phase behavior, and rheology.
通过采用引发剂缓慢进料的新型半间歇乳液聚合方法合成了氟化核壳球。该合成方法得到了高度单分散球体的水分散体，这些球体带有明确的聚乙二醇接枝（聚乙二醇化）。测量结果表明，合成过程实现了高接枝密度，而且该接枝密度由单个聚乙二醇层组成，聚合物在本体中显著伸长超过其回转半径。颗粒核心的氟化赋予了低折射率，使得通过添加相对少量的助溶剂，颗粒能够在水中实现折射率匹配，这使得可以使用光学和基于激光的方法来研究浓缩体系。这些体系在氯化钠溶液中表现出极高的稳定性，但通过添加其他盐可以引入颗粒间的吸引力，在这种情况下，聚集被证明是可逆的。聚乙二醇化球体分散体有望非常适合作为模型系统，用于研究聚乙二醇介导的相互作用对结构、动力学、相行为和流变学等方面的影响。
