Balmer Jennifer A, Armes Steven P, Fowler Patrick W, Tarnai Tibor, Gáspár Zsolt, Murray Kenneth A, Williams Neal S J
Dainton Building, Department of Chemistry, The University of Sheffield, Sheffield, Brook Hill, S3 7HF United Kingdom.
Langmuir. 2009 May 5;25(9):5339-47. doi: 10.1021/la8041555.
The adsorption of small silica particles onto large sterically stabilized poly(2-vinylpyridine) [P2VP] latex particles in aqueous solution is assessed as a potential route to nanocomposite particles with a "core-shell" morphology. Geometric considerations allow the packing efficiency, P, to be related to the number of adsorbed silica particles per latex particle, N. Making no assumptions about the packing structure, this approach leads to a theoretical estimate for P of 86 +/- 4%. Experimentally, dynamic light scattering is used to obtain a plot of hydrodynamic diameter against N, which indicates the conditions required for monolayer coverage of the latex by the silica particles. Transmission electron microscopy confirmed that, at approximately monolayer coverage, calcination of these nanocomposite particles led to the formation of well-defined hollow silica shells. This is interpreted as strong evidence for a contiguous monolayer of silica particles surrounding the latex cores. On this basis, an experimental value for P of 69 +/- 4% was estimated for nanocomposite particles prepared by the heteroflocculation of a 20 nm silica sol with near-monodisperse P2VP latexes of either 463 or 616 nm diameter at approximately pH 10. X-ray photoelectron spectroscopy was used to quantify the extent of latex surface coverage by the silica particles. This technique gave good agreement with the silica packing efficiencies estimated from calcination studies.
评估了小二氧化硅颗粒在水溶液中吸附到大型空间稳定化聚（2-乙烯基吡啶）[P2VP]胶乳颗粒上的情况，将其作为制备具有“核壳”形态的纳米复合颗粒的潜在途径。通过几何考量，可使填充效率P与每个胶乳颗粒吸附的二氧化硅颗粒数量N相关。在不对填充结构做任何假设的情况下，这种方法得出P的理论估计值为86±4%。实验上，使用动态光散射获得流体动力学直径对N的曲线图，该图表明了二氧化硅颗粒对胶乳进行单层覆盖所需的条件。透射电子显微镜证实，在大约单层覆盖时，这些纳米复合颗粒的煅烧导致形成了明确的中空二氧化硅壳。这被解释为围绕胶乳核的二氧化硅颗粒形成连续单层的有力证据。在此基础上，对于通过在约pH 10条件下将20 nm二氧化硅溶胶与直径为463或616 nm的近单分散P2VP胶乳进行异质絮凝制备的纳米复合颗粒，估计其P的实验值为69±4%。使用X射线光电子能谱来量化二氧化硅颗粒对胶乳表面的覆盖程度。该技术与从煅烧研究估计的二氧化硅填充效率具有良好的一致性。
