Department of Applied Mathematics, Research School of Physics and Engineering, Australian National University , Canberra, 0200 ACT, Australia.
Langmuir. 2013 Dec 3;29(48):14748-55. doi: 10.1021/la403439r. Epub 2013 Nov 21.
The adsorption isotherms and aggregate structures of adsorbed surfactants on smooth thin-film surfaces of mineral oxides have been studied by optical reflectometry and atomic force microscopy (AFM). Films of the mineral oxides of titania, alumina, hafnia, and zirconia were produced by atomic layer deposition (ALD) with low roughness. We find that the surface strongly influences the admicelle organization on the surface. At high concentrations (2 × cmc) of cetyltrimethylammonium bromide (CTAB), the surfactant aggregates on a titania surface exhibit a flattened admicelle structure with an average repeat distance of 8.0 ± 1.0 nm whereas aggregates on alumina substrates exhibit a larger admicelle with an average separation distance of 10.5 ± 1.0 nm. A wormlike admicelle structure with an average separation distance of 7.0 ± 1.0 nm can be observed on zirconia substrates whereas a bilayered aggregate structure on hafnia substrates was observed. The change in the surface aggregate structure can be related to an increase in the critical packing parameter through a reduction in the effective headgroup area of the surfactant. The templating strength of the surfaces are found to be hafnia > alumina > zirconia > titania. Weakly templating surfaces are expected to have superior biocompatibility.
通过光学反射测量法和原子力显微镜（AFM）研究了光滑的矿物氧化物薄膜表面上吸附表面活性剂的吸附等温线和聚集结构。通过原子层沉积（ALD）在低粗糙度下生成了 TiO2、Al2O3、HfO2 和 ZrO2 等矿物氧化物的薄膜。我们发现表面强烈影响表面上的准胶束组织。在十六烷基三甲基溴化铵（CTAB）的高浓度（2×cmc）下，表面活性剂在 TiO2 表面上的聚集物呈现出扁平化的准胶束结构，平均重复距离为 8.0 ± 1.0nm，而在 Al2O3 基底上的聚集物则呈现出较大的准胶束，平均分离距离为 10.5 ± 1.0nm。在 ZrO2 基底上可以观察到具有平均分离距离为 7.0 ± 1.0nm 的蠕虫状准胶束结构，而在 HfO2 基底上则观察到双层聚集结构。表面聚集结构的变化可以通过表面活性剂的有效头基面积的减少与临界堆积参数的增加相关联。发现表面的模板强度为 HfO2＞Al2O3＞ZrO2＞TiO2。预计弱模板化表面具有优异的生物相容性。
