Role of Casting Solvent on Nanoparticle Dispersion in Polymer Nanocomposites
Role of Casting Solvent on Nanoparticle Dispersion in Polymer Nanocomposites
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DOI：
10.1021/ma500619g
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发表时间：
2014-08-12
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：
Jouault, Nicolas;Zhao, Dan;Kumar, Sanat K.
我们研究了浇铸溶剂对纳米粒子在聚合物纳米复合材料中最终空间分散的影响。我们制备了裸二氧化硅纳米颗粒和聚（2-乙烯基吡啶）（P2 VP）的纳米复合材料，从两种不同的溶剂-甲基乙基酮（MEK）和吡啶-这是θ/良好的溶剂，分别为聚合物和纳米颗粒铸造。在MEK中，我们表明，P2 VP强烈吸附到二氧化硅表面上，以创建一个时间稳定的绑定聚合物层。所得的“毛状”颗粒在空间上稳定以防止团聚，并且因此总是实现良好的NP在PNC中的分散，而与P2 VP分子量、浓度或NP负载无关。相反，在吡啶中，P2 VP不吸附在二氧化硅NP上。因此，在这种情况下的相行为是由静电排斥，聚合物引起的耗尽吸引力，和扩散限制NP聚集的动力学减速之间的微妙平衡。虽然在干燥的PNC中几乎没有残留溶剂，并且由于这些分散状态在退火时几乎没有改变，这些结果用于强调浇铸溶剂在聚合物基质中NP的空间分散状态中所起的关键作用。
We investigate the influence of casting solvent on the final spatial dispersion of nanoparticles (NPs) in polymer nanocomposites (PNCs). We prepared nanocomposites of bare silica NPs and poly(2-vinylpyridine) (P2VP) by casting from two different solvents-methyl ethyl ketone (MEK) and pyridine-which are theta/good solvents, respectively, for both the polymer and the NPs. In MEK, we show that P2VP strongly adsorbs onto the silica surface to create a temporally stable bound polymer layer. The resulting "hairy" particles are sterically stabilized against agglomeration, and thus good NP dispersion in PNCs is always achieved, independent of P2VP molecular weight, concentration, or NP loading. On the contrary, in pyridine, P2VP does not adsorb on the silica NPs. The phase behavior in this case is thus governed by a subtle balance among electrostatic repulsion, polymer-induced depletion attraction, and the kinetic slowdown of diffusion-limited NP aggregation. While there is little remnant solvent in the dry PNC, and since these dispersion states are hardly altered on annealing, these results serve to emphasize the crucial role played by the casting solvent in the spatial dispersion state of NPs in a polymer matrix.