Collaborative Research: Unusual Temperature Dependent Behavior of Polymer Nanocomposites

将纳米粒子集成到聚合物中可以提高复合材料的热性能、力学性能和形状变化性能。在传统的聚合物复合材料中，通常使用化学上与基质聚合物相同的聚合物对纳米颗粒表面进行功能化处理，以控制颗粒的分散。然而，在高温加工和应用过程中保持分散性和力学性能对聚合物产品的制造和性能至关重要。这笔赠款的重点是了解颗粒-聚合物相互作用对分散性、机械性能和加工的作用。为了实现这一目标，PI将专注于对可逆机械响应进行按需控制的材料系统设计。可逆加筋复合材料可用于各种应用，从软机器人、柔性电子产品到受热时应保持机械完整性的可注射植入物。这项合作工作提供了一个基础研究计划，整合了PI在聚合物纳米复合材料的实验和分子动力学模拟方面的专业知识，以研究潜在的机制。此外，该项目还为研究生和本科生提供纳米材料设计和加工方面的教育。为了在高中教育中拓宽纳米科学和纳米材料的知识，PI旨在为新泽西州和纽约地区的教师组织一个研讨会。该团队旨在探索聚合物纳米复合材料中的可逆硬化现象。假设包覆高玻璃化转变温度(Tg)聚合物并分散在低玻璃化转变温度(Tg)聚合物中的颗粒在受热时发生液-固相变。实验工作旨在展示这一行为在具有不同玻璃化转变温差的各种可混溶共混物中的普遍性。这一现象将被应用到磁性纳米颗粒上，以证明可以通过颗粒的局部加热来调节机械行为。此外，为了捕捉实验系统设计中的物理和力学响应，还计划进行额外的实验，以关联不对称共混物在界面上的局部粘度和粒子松弛。模拟将并行运行，并将用于指导材料设计，更重要的是将确定导致高温硬化的原子尺度物理。将进行加工研究，以了解界面层的稳定性，以及加工后的复合材料结构(形态)和性能。加工结果与材料设计非常相关，例如对于生物医学植入物，在其预期用于体内骨形成的过程中，材料将经历频繁且可控的动态载荷。

Integration of nanoparticles into polymers leads to enhancement in thermal, mechanical and shape changing properties of composite materials. Functionalizing nanoparticle surfaces with polymers that are chemically identical to matrix polymer are commonly employed in conventional polymer composites simply to control particle dispersion. However, maintaining dispersion and mechanical properties during high temperature processing and applications holds a critical importance in manufacturing and performance of polymeric products. This grant focuses on understanding the role of particle-polymer interactions on dispersion, mechanical properties and processing. Towards this goal, the PIs will focus on a material system design with on-demand control on reversible mechanical response. Reversibly stiffening composites can be used in various applications from soft robotics, flexible electronics to injectable implants where mechanical integrity should be maintained when heated. This collaborative work offers a fundamental research plan integrating the expertise of the PIs on experimental and molecular dynamics simulations on polymer nanocomposites to study the underlying mechanisms. In addition, the project offers to educate graduate and undergraduate students on nanomaterials design and processing. To broaden the knowledge of nanoscience and nanomaterials in high school education, the PIs aim to organize a workshop for teachers in New Jersey and New York area.The team aims to explore the phenomenon of reversible stiffening in polymer nanocomposites. It is hypothesized that particles coated with a high glass transition temperature (Tg) polymer and dispersed in a low-Tg polymer exhibit liquid-to-solid transition upon heating. Experimental work is designed to show the universality of this behavior in various miscible blends with different glass-transition temperature differences. The phenomenon will be employed on magnetic nanoparticles to demonstrate that the mechanical behavior can be regulated with local heating of particles. Moreover, additional experiments to relate the local viscosity and particle relaxations in asymmetric blends on interphases are planned in order to capture the physics and mechanical response in the experimental system design. Simulations will run in parallel and will be used to guide the material design and more importantly will identify the atomistic scale physics that leads to stiffening at high temperatures. Processing studies will be conducted to understand the stability of interphase layers, and composite structure (morphology) and properties after processing. The processing results are very relevant for the material design such as for biomedical implants where materials will experience frequent and controlled dynamic loadings during their intended use for in vivo bone formation.