Soft Matter Complex Systems as Model Biological Systems

在本项目中，我们研究了软物质复杂系统作为模型生物系统的结构形成。我们特别关注了以下三个可能与生物功能有关的复杂系统。1)液晶+聚合物复合物体系：具有各向异性形状的生物聚合物，如蛋白质、病毒、肌动蛋白丝等，在生物环境下形成特征性聚集体。各向异性粒子之间的基本吸引相互作用可能源于所谓的耗竭相互作用。在本研究中，我们发现刚性聚合物与卷状聚合物链相比，耗竭相互作用增强了约1000倍。这是由于刚性聚合物链的有效排除体积大。2)表面活性剂膜+聚合物链（胶体颗粒）体系：我们研究了客体组分（聚合物或球形胶体颗粒）限制在柔性板层间狭缝之间的影响。在片层相中加入中性聚合物会引起有吸引力的片层间相互作用。另一方面，限制在柔性片层膜之间的球形胶体粒子减少了片层的波动波动，带来了片层间的排斥相互作用。3)聚合物接枝表面活性剂膜我们研究了接枝聚合物链对层状膜弯曲模量和膜间相互作用的影响。聚合物接枝膜的弯曲模量与聚合物链的端到端距离的平方成比例地增加。蘑菇层被重新规格化到膜厚度，这增强了排斥性helrich相互作用。然而，当修饰聚合物链的尺寸增加到层间距离时，蘑菇被挤压，以优化层间电位。接枝聚合物尺寸的进一步增大导致层间相分离。少

In this project, we investigated the structure formation of Soft Matter Complex Systems as Model Biological Systems. Especially we focused on the following three complex systems, which may have relation to the biological functionalities.1)Liquid crystal + polymer complex system :Biopolymers having anisotropic shapes, such as protein, virus and actin-filament, forms characteristic aggregates in the biological circumstance. The basic attractive interaction between the anisotropic particles may be originated from the so-called depletion interaction. In this study we found that the rigid polymer enhances the depletion interaction about 1000 times compared with the case of coil-like polymer chains. This is due to the large effective excluded volume of the rigid polymer chains.2)Surfactant membrane + polymer chain (colloidal particle) system :We have investigated effects of a guest component (polymer or spherical colloidal particle) confined between flexible lamellar slits on the inter-lamel … More lar interaction. The addition of the neutral polymer into the lamellar phase induces an attractive inter-lamellar interaction. On the other hand, the spherical colloidal particles confined between the flexible lamellar membranes reduce the undulational fluctuations of lamellae and bring a repulsive inter-lamellar interaction.3)Polymer grafted surfactant membranesWe have investigated the effects of grafted polymer chains on the bending modulus and the inter-membrane interactions of lamellar membranes. The bending modulus of the polymer grafted membranes increases in proportion to the square of the end to end distance of the polymer chain. The mushroom layer is renormalized to the membrane thickness, which enhances the repulsive Helfrich interaction. When the size of the decorated polymer chain increases to the inter-lamellar distance, however, the mushroom is squeezed so as to optimize the inter-lamellar potential. Further increase of the grafted polymer size brings a lamellar-lamellar phase separation. Less