Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States.
Langmuir. 2013 Jul 16;29(28):8989-96. doi: 10.1021/la401522v. Epub 2013 Jul 1.
The governing parameters controlling the miscibility of particle additives within polymeric host media are analyzed for the particular case of silica particle fillers embedded within a poly(methyl methacrylate) (PMMA) matrix. For athermal polymer-graft modification of particles (corresponding to equal chemical composition of graft and matrix polymer), compatibility is found to be a sensitive function of the degree of polymerization of graft and host polymer chains as well as the particle radius. In agreement with theoretical predictions, uniform particle dispersion is observed if the degree of polymerization of grafted chains is comparable to (or exceeds) the corresponding value of the polymer matrix. The resulting restriction to high degree of polymerization limits the accessible inorganic fraction that is attainable in athermal particle/polymer blends. In contrast, favorable interaction between grafted polymer chains and the polymeric host (as realized in the case of poly(styrene-r-acrylonitrile)-grafted particles embedded within PMMA matrix) is shown to facilitate thermodynamically stable and uniform particle dispersion across the entire compositional range even in the limit of large particle size, short grafted chains, and high molecular matrix chains. The synthesis of thermoplastic composite materials with inorganic fraction exceeding 50 vol % combining quantitative optical limiting within the UV frequency range and polymer-like mechanical properties is demonstrated.
本文分析了控制颗粒添加剂在聚合物基体中混溶性的控制参数，特别针对二氧化硅颗粒填充聚甲基丙烯酸甲酯（PMMA）基体的情况。对于非热聚合物接枝改性的颗粒（对应于接枝和基体聚合物具有相同的化学组成），相容性是接枝和主链聚合物链的聚合度以及颗粒半径的敏感函数。根据理论预测，如果接枝链的聚合度与聚合物基体的相应值相当（或超过），则可以观察到均匀的颗粒分散。接枝链的高聚合度限制了非热颗粒/聚合物共混物中可达到的高无机分数。相比之下，接枝聚合物链与聚合物基体之间的有利相互作用（如在聚苯乙烯-r-丙烯腈接枝颗粒嵌入 PMMA 基体的情况下）被证明可以促进整个组成范围内热力学稳定且均匀的颗粒分散，即使在大颗粒尺寸、短接枝链和高分子基体链的极限情况下也是如此。本文证明了可以合成具有超过 50%体积分数的无机部分的热塑性复合材料，其在 UV 频率范围内具有定量光限制和类似聚合物的机械性能。
