Compatibilizing Immiscible Polymer Blends with Sparsely Grafted Nanoparticles
Compatibilizing Immiscible Polymer Blends with Sparsely Grafted Nanoparticles
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DOI：
10.1021/acs.macromol.0c02108
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发表时间：
2020-12-08
期刊：
影响因子：
5.5
通讯作者：
Kumar, Sanat K.
中科院分区：
文献类型：
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作者：
Alkhodairi, Husam;Russell, Sebastian T.;Kumar, Sanat K.
使用纳米粒子(NP)增容不相容的聚合物共混物仍然是一个持续的挑战，需要对NP的分散和局部化进行高水平的控制。在这里，我们展示了疏松地接枝到长聚苯乙烯(PS)链上的二氧化硅纳米颗粒是类似表面活性剂的，因为它们允许核-核、核-基质和电晕-基质相互作用。当放置在不相容的聚甲基丙烯酸甲酯(PMMA)-PS界面上时，硅芯与一个组分(PMMA)强烈相互作用，而电晕与另一个组分(PS)混合。这些精心设计的纳米粒子被证明是有效的稳定剂，甚至性能优于嵌段共聚物。虽然这种类似表面活性剂的行为是显而易见的，并且是根据现有的想法来理解的，但我们利用的一个新概念是界面自由能分布的形状如何受到表面接枝密度的影响。对于最佳选择的接枝密度和接枝链长，我们发现了一个近乎对称的自由能分布，它是界面上NP接触角的函数，确保了NPs在稳定方面最有效的区域被强烈地局域化。
The use of nanoparticles (NPs) to compatibilize immiscible polymer blends remains an ongoing challenge requiring a high level of control over the NP dispersion and localization. Here, we show that silica NPs "sparsely" grafted with long polystyrene (PS) chains are surfactant-like because they permit core-core, core-matrix, and corona-matrix interactions. When placed at an immiscible polymethyl methacrylate (PMMA)-PS interface, the silica core strongly interacts with one component (PMMA), while the corona mixes with the other (PS). These carefully designed NPs are demonstrated to be efficient stabilizers, even outperforming block copolymers. While such surfactant-like behavior is evident, and understood on the basis of existing ideas, a new concept that we leverage is how the shape of the interfacial free energy profile is affected by the surface grafting density. For an optimally chosen grafting density and graft chain length, we find a nearly symmetric free energy profile as a function of the NP contact angle at the interface, ensuring that the NPs are strongly localized in a region where they are the most efficient in terms of stabilization.