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(带电的胶体颗粒被固定在不带电荷的水凝胶基质中)，我们为发展新的诊断技术奠定了严格的理论基础，从长远来看，这些技术可能会检测水凝胶复合材料中的生物分子反应，监测固定组织培养中的细胞代谢，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来演示实验室测量和纳米复合材料微结构的物理化学特征之间的定量联系。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)，我们开发了一个独创的理论，成功地量化了不可穿透的纳米颗粒如何出人意料地提高用于气体分离的玻璃膜的渗透性和反向选择性。为了预测膜在工业相关条件下的性能，我们将把目前的理论扩展到计算纳米颗粒聚集，这反过来将被用来预测高颗粒负载下的膜渗透性和选择性。我的研究项目还成功地应用电动理论开发了关于接枝到磷脂膜表面的聚合物的动力学和组织的假说。由于聚合物动力学在实验室诊断中起着重要作用，并影响脂质体药物制剂的稳定性和有效性，因此我们将在电剪切力和流体力学剪切力的影响下，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，我们将开发一种理论来解释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机械测试，使用我的团队最近建造的复杂的光学镊子设备，设计出实用的策略，控制用于生物传感和纳过滤应用的纳米管的合成和组装。

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.