Dang Alei, Ojha Satyajeet, Hui Chin Ming, Mahoney Clare, Matyjaszewski Krzysztof, Bockstaller Michael R
Department of Materials Science and Engineering, Carnegie Mellon University , 5000 Forbes Avenue, Pittsburgh, Pennsylvania 15213, United States.
Langmuir. 2014 Dec 9;30(48):14434-42. doi: 10.1021/la5037037. Epub 2014 Nov 26.
The role of polymeric ligands on the optical transparency of polymer-matrix composites is analyzed by evaluating the effect of surface modification on the scattering cross-section of particle fillers in uniform particle dispersions. For the particular case of poly(styrene-r-acrylonitrile)-grafted silica particles embedded in poly(methyl methacrylate), it is shown that the tethering of polymeric chains with appropriate optical properties (such as to match the effective refractive index of the brush particle to the embedding matrix) facilitates the reduction of the particle scattering cross-section by several orders of magnitude as compared to pristine particle analogues. The conditions for minimizing the scattering cross-section of particle fillers by polymer-graft modification are established on the basis of effective medium as well as core-shell Mie theory and validated against experimental data on uniform liquid and solid particle dispersions. Effective medium theory is demonstrated to provide robust estimates of the "optimum polymer-graft composition" to minimize the scattering cross-section of particle fillers even in the limit of large particle dimensions (comparable to the wavelength of light). The application of polymer-graft modification to the design of large (500 nm diameter) silica particle composites with reduced scattering cross-section is demonstrated.
通过评估表面改性对均匀颗粒分散体中颗粒填料散射截面的影响，分析了聚合物配体对聚合物基复合材料光学透明度的作用。对于嵌入聚甲基丙烯酸甲酯中的聚（苯乙烯 - 共 - 丙烯腈）接枝二氧化硅颗粒这一特殊情况，研究表明，具有适当光学性质的聚合物链的连接（例如使刷状颗粒的有效折射率与嵌入基质相匹配）相比于原始颗粒类似物，有助于将颗粒散射截面降低几个数量级。基于有效介质理论以及核壳米氏理论，确定了通过聚合物接枝改性使颗粒填料散射截面最小化的条件，并针对均匀液体和固体颗粒分散体的实验数据进行了验证。结果表明，有效介质理论能够提供对“最佳聚合物接枝组成”的可靠估计，以最小化颗粒填料的散射截面，即使在大颗粒尺寸（与光波长相当）的情况下也是如此。展示了聚合物接枝改性在设计具有减小散射截面的大尺寸（直径500 nm）二氧化硅颗粒复合材料中的应用。
