Effect of polymer–nanoparticle interactions on solvent-driven infiltration of polymer (SIP) into nanoparticle packings: a molecular dynamics study
Effect of polymer–nanoparticle interactions on solvent-driven infiltration of polymer (SIP) into nanoparticle packings: a molecular dynamics study
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DOI：
10.1039/c9me00148d
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发表时间：
2020-03
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通讯作者：
R. Venkatesh;Tianren Zhang;N. Manohar;K. Stebe;Robert A. Riggleman;Daeyeon Lee
中科院分区：
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作者：
R. Venkatesh;Tianren Zhang;N. Manohar;K. Stebe;Robert A. Riggleman;Daeyeon Lee
天然形成的纳米复合材料，如珠质，其特殊的机械性能归功于由小体积聚合物桥接的高负荷血小板。聚合物渗透到密集的纳米粒子集合中，为制造仿生纳米复合材料提供了一种强大的、潜在的可扩展方法，可以模仿珍珠层的结构。溶剂驱动的聚合物渗透（SIP）进入玻璃聚合物薄膜上形成的纳米颗粒填料中，是通过纳米颗粒之间的空隙（NP）中溶剂的毛细凝结诱导的，随后聚合物的塑化和运输进入充满液体的孔隙中，导致纳米复合结构的形成。为了了解聚合物-纳米颗粒相互作用对聚合物在SIP中渗透动力学的影响，我们进行了分子动力学模拟。研究了聚合物的渗透机理以及聚合物与NPs相互作用对渗透动力学的影响。根据相互作用的强度，聚合物渗透要么遵循(a)溶解主导的渗透，其中增塑化的聚合物链在孔隙中保持溶剂化并迅速扩散到填料中，要么遵循(b)粘附主导的运输，其中链被吸附到纳米颗粒表面并缓慢地通过纳米颗粒薄膜作为一个明确的前沿。随着粘接强度的增加，出现非单调趋势；随着黏附力的增加，在黏附和溶解的共同作用下，链的渗透速度加快，但当聚合物-纳米颗粒的黏附作用占主导地位时，链的渗透速度最终减慢。
Naturally occurring nanocomposites like nacre owe their exceptional mechanical properties to high loadings of platelets that are bridged by small volume fractions of polymers. Polymer infiltration into dense assemblies of nanoparticles provides a powerful and potentially scalable approach to manufacture bio-inspired nanocomposites that mimic nacre's architecture. Solvent-driven infiltration of polymers (SIP) into nanoparticle packings formed on top of glassy polymer films is induced via capillary condensation of a solvent in the interstitial voids between nanoparticles (NP), followed by plasticization and transport of polymers into the liquid-filled pores, leading to the formation of the nanocomposite structure. To understand the effect of polymer–nanoparticle interactions on the dynamics of polymer infiltration in SIP, we perform molecular dynamics simulations. The mechanism of polymer infiltration and the influence of interactions between polymer and NPs on the dynamics of the process are investigated. Depending on the strength of interaction, polymer infiltration either follows (a) dissolution-dominated infiltration where plasticized polymer chains remain solvated in the pores and rapidly diffuse into the packing or (b) adhesion-dominated transport where the chains adsorb onto the nanoparticle surface and move slowly through the nanoparticle film as a well-defined front. A non-monotonic trend emerges as the adhesion strength is increased; the infiltration of chains becomes faster with the co-operative effect of adhesion and dissolution as adhesion increases but eventually slows down when the polymer–nanoparticle adhesion dominates.