Soft matter: complex transport processes and micro-mechanics

我的研究项目最近在理解聚合物复合材料中发生的复杂传输过程方面做出了几项重要贡献。首先，对于水凝胶复合材料（带电的胶体颗粒固定在不带电的水凝胶基质中），我们已经为推进新的诊断技术建立了严格的理论基础，从长远来看，这些技术可能会感知水凝胶复合材料中的生物分子反应，监测固定组织培养物中的细胞代谢，并促进乳腺癌的早期发现。在这项工作中，我们将开发模型实验系统，以证明实验室测量与纳米复合材料微观结构的物理化学特性之间的定量联系。其次，对于聚合物纳米复合材料（纳米颗粒分散在聚合物熔体和玻璃中），我们开发了一个原创理论，成功地量化了不可穿透的纳米颗粒如何出乎意料地增强用于气体分离的玻璃膜的渗透性和反向选择性。为了预测在工业相关条件下的膜性能，我们将扩展目前的理论来计算纳米颗粒聚类，这反过来将用于预测高颗粒负载下膜的渗透性和选择性。我的研究项目还成功地应用了电动力学理论，提出了关于接枝到磷脂膜表面的聚合物的动力学和组织的假设。由于聚合物动力学在实验室诊断中起着重要作用，并影响脂质体药物配方的稳定性和有效性，我们将在电动力和水动力剪切力的影响下通过直接成像聚合物衍生磷脂来实验验证我们的假设。最后，我们将发展一种理论来阐明聚合物纳米管自发弯曲和折叠的倾向。这项研究将结合理论和微力学测试，使用我的团队最近建造的一个复杂的光学镊子装置，设计出控制纳米管合成和组装的实用策略，用于生物传感和纳滤应用。

My research program has recently made several important contributions to understanding complex transport processes that take place in polymeric composites. Firstly, for hydrogel composites (where charged colloidal particulates are immobilized in uncharged hydrogel matrices), we have established a rigorous theoretical foundation for advancing novel diagnostic techniques that may, in the longer term, sense biomolecular reactions in hydrogel composites, monitor cell metabolism in immobilized tissue cultures, and facilitate the early detection of breast cancer. In this work, we will develop model experimental systems to demonstrate quantitative links between laboratory measurements and physicochemical characteristics of the nanocomposite microstructure. Secondly, for polymeric nanocomposites (where nanoparticulates are dispersed in polymer melts and glasses), we developed an original theory that successfully quantifies how impenetrable nanoparticles unexpectedly enhance the permeability and reverse selectivity of glassy membranes used for gas separations. To predict membrane performance under industrially relevant conditions, we will extend the present theory to compute nanoparticle clustering, which, in turn, will be used to predict membrane permeability and selectivity at high particle loadings. My research program has also successfully applied electro-kinetic theory to develop hypotheses concerning the dynamics and organization of polymers grafted to the surfaces of phospholipid membranes. Because the polymer dynamics play an important role in laboratory diagnostics, and influence the stability and effectiveness of liposomal drug formulations, we will experimentally test our hypotheses by directly imaging polymer-derivatized phospholipids while under the influence of electrical and hydrodynamic shear forces. Finally, we will develop a theory to elucidate the propensity of polymeric nano-tubes to spontaneously buckle and fold. This research will couple theory and micro-mechanical testing, using a sophisticated optical tweezers apparatus my group has recently built, to devise practical strategies for controlling the synthesis and assembly of nanotubes for biosensing and nanofiltration applications.