Infiltration dynamics of poly(styrene-stat-2-vinylpyridine) (PS-stat-P2VP) statistical copolymers (StCPs) undergoing capillary rise infiltration into the interstices of silica nanoparticle (SiO₂ NP) packings are investigated by in situ spectroscopic ellipsometry with varying ratios of strongly interacting 2-vinylpyridine (2VP) and weakly interacting styrene (S) repeat units. As the fraction of 2VP (f_P2VP) increases, a nonmonotonic dependence is observed in the time required to fully fill the interstices of the SiO₂ NP packings (t_inf) and the effective viscosity (η_eff). To understand the mechanism behind the nonmonotonic trend in infiltration dynamics, polymer properties such as zero-shear viscosity (η₀) and glass transition temperature (T_g) are considered; however, these factors fail to explain the trend. When the strong interactions between 2VP and SiO₂ are suppressed by modifying the surface of SiO₂ NPs with the epoxide group, the infiltration dynamics no longer show strong dependence on f_P2VP. This result indicates the important role played by the 2VP unit in the anomalous slowdown observed in StCPs, possibly by controlling its conformation on the pore surface and the interactions between the surface-adsorbed chains and chains that are translated through the pores.

中文翻译：

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统计共聚物组成对毛细管上升浸润动力学的非单调影响


通过原位光谱椭圆偏振法研究了聚（苯乙烯-stat-2-乙烯基吡啶）（PS-stat-P2VP）统计共聚物 （StCPs） 的渗透动力学，这些共聚物经历了毛细管上升渗透到二氧化硅纳米颗粒 （SiO₂ NP） 填料的间隙中，具有不同比例的强相互作用 2-乙烯基吡啶 （2VP） 和弱相互作用的苯乙烯 （S） 重复单元。随着 2VP （f_P2VP） 分数的增加，在完全填充 SiO₂ NP 填料的空隙所需的时间 （t_inf） 和有效粘度 （η_eff） 中观察到非单调依赖性。为了了解渗透动力学中非单调趋势背后的机制，考虑了零剪切粘度 （η₀） 和玻璃化转变温度 （T_g） 等聚合物特性;然而，这些因素无法解释这种趋势。当通过用环氧化物基团修饰 SiO₂ NPs 的表面来抑制 2VP 和 SiO₂ 之间的强相互作用时，渗透动力学不再表现出对 f_P2VP的强烈依赖性。这一结果表明 2VP 单元在 StCPs 中观察到的异常减慢中发挥了重要作用，可能是通过控制其在孔表面的构象以及表面吸附链与通过孔隙平移的链之间的相互作用。