Soft matter: complex transport processes and micro-mechanics

我的研究计划最近做出了几个重要的贡献，了解复杂的传输过程中发生的聚合物复合材料。首先，对于水凝胶复合材料（其中带电的胶体颗粒固定在不带电的水凝胶基质中），我们已经建立了严格的理论基础，用于推进新的诊断技术，从长远来看，可以检测水凝胶复合材料中的生物分子反应，监测固定化组织培养物中的细胞代谢，并促进乳腺癌的早期检测。在这项工作中，我们将开发模型实验系统，以证明实验室测量和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（其中纳米颗粒分散在聚合物熔体和玻璃中），我们开发了一种原始理论，成功地量化了不可渗透的纳米颗粒如何意外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，我们将扩展本理论以计算纳米颗粒聚集，这反过来将用于预测高颗粒负载下的膜渗透性和选择性。我的研究计划也成功地应用电动力学理论来发展有关动力学和组织的聚合物接枝到磷脂膜表面的假设。由于聚合物动力学在实验室诊断中起着重要的作用，并影响脂质体药物制剂的稳定性和有效性，我们将通过直接成像聚合物衍生的磷脂，同时在电力和流体动力学剪切力的影响下，实验测试我们的假设。最后，我们将发展一个理论来阐明聚合物纳米管自发弯曲和折叠的倾向。这项研究将耦合理论和微机械测试，使用一个复杂的光镊装置，我的小组最近建立，设计控制合成和组装纳米管的生物传感和纳米过滤应用的实用策略。

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.