Increases in Miscibility of a Binary Polymer Blend Confined within a Nanoparticle Packing
Increases in Miscibility of a Binary Polymer Blend Confined within a Nanoparticle Packing
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DOI：
10.1021/acs.macromol.2c01918
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发表时间：
2023-01
期刊：
影响因子：
5.5
通讯作者：
Anastasia Neuman;Shan Zhang;Daeyeon Lee;Robert A. Riggleman
中科院分区：
文献类型：
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作者：
Anastasia Neuman;Shan Zhang;Daeyeon Lee;Robert A. Riggleman
尽管已经探索了各种物理和化学策略，但聚合物共混物的增容已被证明是难以捉摸的。聚合物的限制已经显示出诱导这些材料的玻璃化转变温度、动力学和形态的实质性和有时意想不到的变化。虽然限制共混物的薄膜已被证明会影响相分离结构和链的流动性，限制聚合物混合物的相容性的影响是少得多的理解。在这里，我们提出了一个计算研究，使用场论模拟，以了解热力学的聚合物共混物，被限制在纳米颗粒填料的间隙，其中两种聚合物与纳米颗粒表面的中性相互作用。我们计算了它们的双节点相包络，并表明，两种聚合物，将经历宏观相分离变得混溶时，他们受到极端的纳米约束。诱导相分离所需的排斥力的强度随着限制的增加而显著增加。我们发现，这种增强的相容性是由相分离时的熵罚增加和随着限制的增加而减少的排斥力驱动的。我们涉及的焓的变化，以减少在纳米粒子表面附近的聚合物-聚合物接触的数量和熵的变化，以减少构象自由度由于形成的聚合物-聚合物界面附近的纳米粒子表面。在纳米颗粒填料中的聚合物的约束诱导混合可以使纳米复合材料薄膜和膜的机械和传输性能的精确调节成为可能。
Despite various physical and chemical strategies that have been explored, compatibilization of polymer blends has proved elusive. Confinement of polymers has shown to induce substantial and at times unexpected changes in glass-transition temperature, dynamics, and morphology of these materials. Although confinement of blends to thin films have shown to influence phase separation structure and chain mobility, the impact of confinement on the miscibility of polymer mixtures is much less understood. Here, we present a computational study using field-theoretic simulations to understand the thermodynamics of polymer blends that are confined in the interstices of nanoparticle packings where both polymers have neutral interactions with the nanoparticle surfaces. We calculate their binodal phase envelopes and show that two polymers that would undergo macroscopic phase separation become miscible when they are subjected to extreme nanoconfinement. The strength of the repulsion required to induce phase separation increases significantly as confinement increases. We find that this enhanced miscibility is driven by both an increase in entropic penalty upon phase separation and a decrease in enthalpic repulsion with increasing confinement. We relate the change in enthalpy to a reduction in the number of polymer–polymer contacts near nanoparticle surfaces and the change in entropy to a reduction in conformational freedom due to the formation of a polymer–polymer interface near nanoparticle surfaces. Confinement-induced mixing of polymers in nanoparticle packings could enable precise tuning of mechanical and transport properties of nanocomposite films and membranes.