Grafted Nanoparticle Surface Wetting during Phase Separation in Polymer Nanocomposite Films
Grafted Nanoparticle Surface Wetting during Phase Separation in Polymer Nanocomposite Films
复制标题
聚合物纳米复合薄膜相分离过程中接枝纳米颗粒的表面润湿
DOI：
10.1021/acsami.1c09233
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发表时间：
2021
影响因子：
9.5
通讯作者：
Rannou, Patrice
中科院分区：
文献类型：
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作者：
Maguire, Shawn M.;Boyle, Michael J.;Bilchak, Connor R.;Demaree, John Derek;Keller, Austin W.;Krook, Nadia M.;Ohno, Kohji;Kagan, Cherie R.;Murray, Christopher B.;Rannou, Patrice
聚合物接枝纳米粒子在聚合物纳米复合膜中的润湿是由组分之间的表面能差异和整体热力学，即相互作用参数χ的值所驱动的。在含有25wt%聚甲基丙烯酸甲酯(PMMA)接枝二氧化硅纳米颗粒(PMMA-NPs)的PNC中，研究了当在较低临界溶液温度(LCST，160°C)以上热处理时，这些贡献之间的相互作用。原子力显微镜(AFM)研究表明，颗粒的面密度迅速增加，然后接近随机紧密堆积的硬球的80%。与170°C相比，190°C时观察到的面密度略高。PMMA-NPs还可以在类似聚合物混合物不稳定的条件下防止PNC膜脱湿。透射电子显微镜成像表明，PMMA-NPs对称润湿了两个界面，并形成横跨自由表面和衬底界面的柱状物。利用掠入射卢瑟福背散射光谱(GI-RBS)，PMMA-NP表面过剩(Z*)最初随时间迅速增加，然后在较长时间内趋于恒定值。与面密度一致，Z*在更深的淬火深度略大，这归因于PMMA刷子和SAN段之间更不利的相互作用。用早期的Z*值来确定PMMA-NP扩散系数，其值明显大于理论预测值。这些研究为PNC中润湿和相分离之间的相互作用提供了深入的见解，并可用于表面依赖性质的纳米技术应用，如润湿性、耐久性和摩擦力。
Wetting of polymer-grafted nanoparticles (NPs) in a polymer nanocomposite (PNC) film is driven by a difference in surface energy between components as well as bulk thermodynamics, namely, the value of the interaction parameter, χ. The interplay between these contributions is investigated in a PNC containing 25 wt % polymethyl methacrylate (PMMA)-grafted silica NPs (PMMA-NPs) in poly(styrene-ran-acrylonitrile) (SAN) upon annealing above the lower critical solution temperature (LCST, 160 °C). Atomic force microscopy (AFM) studies show that the areal density of particles increases rapidly and then approaches 80% of that expected for random close-packed hard spheres. A slightly greater areal density is observed at 190 °C compared to 170 °C. The PMMA-NPs are also shown to prevent dewetting of PNC films under conditions where the analogous polymer blend is unstable. Transmission electron microscopy (TEM) imaging shows that PMMA-NPs symmetrically wet both interfaces and form columns that span the free surface and substrate interface. Using grazing-incidence Rutherford backscattering spectrometry (GI-RBS), the PMMA-NP surface excess (Z*) initially increases rapidly with time and then approaches a constant value at longer times. Consistent with the areal density,Z* is slightly greater at deeper quench depths, which is attributed to the more unfavorable interactions between the PMMA brush and SAN segments. TheZ* values at early times are used to determine the PMMA-NP diffusion coefficients, which are significantly larger than theoretical predictions. These studies provide insights into the interplay between wetting and phase separation in PNCs and can be utilized in nanotechnology applications where surface-dependent properties, such as wettability, durability, and friction, are important.