Bao Huixin, Bihr Timo, Smith Ana-Sunčana, Klupp Taylor Robin N
Institute of Particle Technology, FAU Erlangen-Nürnberg, Cauerstr. 4, 91058 Erlangen, Germany.
Nanoscale. 2014 Apr 21;6(8):3954-66. doi: 10.1039/c3nr04016j. Epub 2013 Nov 19.
Patchy particles comprise regions of differing material or chemical functionality on otherwise isotropic cores. To meet the great potential of these anisotropic structures in a wide range of application fields, completely new approaches are sought for the scalable and tunable production of patchy particles, particularly those with nanoscale dimensions. In this paper the synthesis of patchy particles via a simple colloidal route is investigated. Using surfactant-free cationic polystyrene nanospheres as core particles, gold patches are produced through the in situ reduction of chloroauric acid with ascorbic acid. The fact that such nanostructured metal patches can be heterogeneously nucleated on polymer nanospheres is related to the electrostatic interaction between core and metal precursor. Furthermore, the lateral expansion of the gold patches over the polystyrene surface is facilitated by an excess of ascorbic acid. The morphology of the patches is highly dendritic and process-induced variations in the structure are related to gold surface mobility using Monte Carlo simulations based on the diffusion limited aggregation principle. Considering the pH dependent behaviour of ascorbic acid it is possible to predict the moiety which most likely adsorbs to the polymer surface and promotes gold surface diffusion. This enables the judicious adjustment of the pH to also obtain non-dendritic patches. On account of the plasmonic behaviour of gold, the patchy particles have morphology-dependent optical properties. The systematic development of the synthetic approach described here is expected to lay a foundation for the development of functional materials based on the self- or directed-assembly of nanoscale building blocks with anisotropic interactions and properties.
补丁状颗粒在各向同性的核心上包含不同材料或化学功能的区域。为了挖掘这些各向异性结构在广泛应用领域中的巨大潜力，人们正在寻找全新的方法来可扩展且可调控地制备补丁状颗粒，尤其是那些具有纳米尺度尺寸的颗粒。本文研究了通过简单胶体路线合成补丁状颗粒的方法。以无表面活性剂的阳离子聚苯乙烯纳米球作为核心颗粒，通过用抗坏血酸原位还原氯金酸来制备金补丁。这种纳米结构的金属补丁能够在聚合物纳米球上异质成核这一事实与核心和金属前驱体之间的静电相互作用有关。此外，过量的抗坏血酸促进了金补丁在聚苯乙烯表面的横向扩展。补丁的形态高度呈树枝状，基于扩散限制聚集原理的蒙特卡罗模拟表明，结构中由过程引起的变化与金表面的迁移率有关。考虑到抗坏血酸的pH依赖性行为，有可能预测最有可能吸附到聚合物表面并促进金表面扩散的部分。这使得通过明智地调节pH值来获得非树枝状补丁成为可能。由于金的等离子体行为，补丁状颗粒具有与形态相关的光学性质。预计这里所描述的合成方法的系统发展将为基于具有各向异性相互作用和性质的纳米级构建块的自组装或定向组装来开发功能材料奠定基础。
