Brush/Gold Nanoparticle Hybrids: Effect of Grafting Density on the Particle Uptake and Distribution within Weak Polyelectrolyte Brushes
Brush/Gold Nanoparticle Hybrids: Effect of Grafting Density on the Particle Uptake and Distribution within Weak Polyelectrolyte Brushes
复制标题
DOI：
10.1021/la503432x
复制
发表时间：
2014-11-04
期刊：
影响因子：
3.9
通讯作者：
von Klitzing, Regine
中科院分区：
文献类型：
--
作者：
Christau, Stephanie;Moeller, Tim;von Klitzing, Regine
据报道，刷接枝密度对将 13 nm 金纳米粒子 (AuNP) 负载到固定在平坦的不可穿透基底上的刺激响应聚 (N,N-(二甲基氨基乙基) 甲基丙烯酸酯) (PDMAEMA) 刷中的影响。原子转移自由基聚合 (ATRP) 用于通过“接枝”方法从 2-溴-2-甲基-N-(3-(三乙氧基甲硅烷基)丙基)丙酰胺 (BTPAm) 覆盖的硅基板上生长聚合物刷。通过使用引发剂和不能引发聚合的“虚拟”分子的混合物来改变接枝密度。通过改变刷接密度同时保持所有其他参数恒定来进行系统研究。 X 射线反射率是研究混合物空间结构的合适工具，它与扫描电子显微镜和紫外/可见光谱相结合，研究聚合物刷基质内颗粒的负载和相互渗透。颗粒吸收随着接枝密度的降低而增加，并且对于中等接枝密度来说是最高的，因为聚合物链之间有更多的空间。对于极低接枝密度的 PDMAEMA 刷，由于缺乏用于颗粒附着的聚合物基质，颗粒吸收量会降低。表面接枝聚合物链的结构在颗粒附着后发生变化。颗粒固定后，更多的水被纳入刷子基质中，这导致混合材料中聚合物链的膨胀。通过降低相对湿度可以去除刷子中的水，这会导致刷子收缩并迫使 AuNP 彼此靠近。
The effect of the brush grafting density on the loading of 13 nm gold nanoparticles (AuNPs) into stimuli-responsive poly(N,N-(dimethylamino ethyl) methacrylate) (PDMAEMA) brushes anchored to flat impenetrable substrates is reported. Atom-transfer radical polymerization (ATRP) is used to grow polymer brushes via a "grafting from" approach from a 2-bromo-2-methyl-N-(3-(triethoxysilyl) propyl) propanamide (BTPAm)-covered silicon substrate. The grafting density is varied by using mixtures of initiator and a "dummy" molecule that is not able to initiate polymerization. A systematic study is carried out by varying the brush grafting density while keeping all of the other parameters constant. X-ray reflectivity is a suitable tool for investigating the spatial structure of the hybrid, and it is combined with scanning electron microscopy and UV/vis spectroscopy to study the particle loading and interpenetration of the particles within the polymer brush matrix. The particle uptake increases with decreasing grafting density and is highest for an intermediate grafting density because more space between the polymer chains is available. For very low grafting densities of PDMAEMA brushes, the particle uptake decreases because of a lack of the polymer matrix for the attachment of particles. The structure of the surface-grafted polymer chains changes after particle attachment. More water is incorporated into the brush matrix after particle immobilization, which leads to a swelling of the polymer chains in the hybrid material. Water can be removed from the brush by decreasing the relative humidity, which leads to brush shrinking and forces the AuNPs to get closer to each other.