Structure and dynamics of soft condensed matter

液晶、凝胶、聚合物和脂质膜都是软凝聚态物质的例子；这些材料的特点是分子间相互作用弱，机械柔软，对热波动敏感。这些材料中的许多是二维、准二维或分形的，它们表现出丰富的行为范围，包括相变、图案形成和非线性材料特性。它们也有很大的实用价值——隐形眼镜是由聚合凝胶制成的，液晶是许多显示屏的基础——它们可以用作更复杂生物系统的模型。这个领域有潜力产生有趣的物理学和新颖的应用。我们的重点是微观结构和宏观材料性能在几个系统之间的关系。我们研究了由疏水块和导电块组成的共聚物形成的聚合物薄膜的微观结构。这些研究的目标是对离子聚合物的微观结构和电导率之间的关系有基本的了解，从而使这些材料的设计更加明智，这对它们在聚合物电解质膜燃料电池中的应用至关重要。第二个研究领域探索屈服应力流体的微观结构和流变学之间的关系，材料只有在施加临界应力时才流动或屈服；日常生活中的例子包括泥浆、剃须泡沫和蛋黄酱。我们通过研究这些材料的散射光来研究材料在小长度尺度上的扩散和弹性，并表征材料的微观结构。这些研究的目标是揭示屈服应力行为的普遍方面，导致微观理论的发展。我们还研究了囊泡的性质，囊泡是由脂质双层形成的球形壳，用于药物输送系统和模型膜。在这里，我们研究了它们的挤压过程和脂质双分子层的材料特性，包括它们破裂时的张力。这些研究对使用这种技术的研究人员以及对脂质系统的平衡形状和动力学感兴趣的物理学家都很有兴趣。

Liquid crystals, gels, polymers and lipid membranes are all examples of soft condensed matter; these materials are characterized by weak intermolecular interactions, mechanical softness, and a susceptibility to thermal fluctuations.  Many of these materials are either two-dimensional, quasi-two dimensional, or fractal and they exhibit a rich range of behaviour including phase transitions, pattern formation, and non-linear material properties.  They are also of great practical interest - contact lenses are made of polymeric gels, and liquid crystals form the basis for many display screens - and they can be used as models of more complicated biological systems.  This field has the potential both to produce interesting physics and novel applications.      Our focus is the relationship between microscopic structure and macroscopic material properties in several systems. We study the microstructure of polymer films formed from copolymers consisting of hydrophobic and conducting blocks.  The goal of these studies is to achieve fundamental understanding of the relationship between microstructure and conductivity in ionic polymers, leading to more informed design of these materials, critical for their application in polymer electrolyte membrane fuel cells.  A second research area explores the relationship between microstructure and rheology of yield-stress fluids, materials that flow or yield only when a critical stress is applied; everyday examples include mud, shaving foam and mayonnaise.  We study the light scattered by these materials to study diffusion and elasticity at small length scales and to characterize the microstructure of the material.  The goal of these studies is to uncover universal aspects of yield stress behaviour, leading to the development of microscopic theories.  We also study properties of vesicles, spherical shells formed from lipid bilayers that are used in drug delivery systems and as model membranes.  Here we investigate the properties of the extrusion process by which they are made and material properties of lipid bilayers, including the tension at which they rupture.  These studies are of interest to researchers using this technique as well as to physicists interested in the equilibrium shapes and dynamics of lipid systems.