US-Bulgaria Cooperative Research on Computer Simulations of Polydisperse Polymer Systems

这项名为“美国-保加利亚关于多分散聚合物系统计算机模拟的合作研究”的提案将由乔治亚大学的David P. Landau博士和索菲亚大学的Andrey I. Milchev博士共同完成。它设想了一个雄心勃勃的研究计划，旨在阐明在吸附表面存在的半柔性聚合物链的多分散系统的复杂合作行为。由于这种系统的热力学性质到目前为止还不为人所知，研究人员相信，在三年的合作中，他们可以产生足够数量的结果，以便对所讨论的现象有一个完整的了解。研究方向应集中在：(1)二维失向相变顺序的确定；(2)建立能量相互作用、温度和密度多参数空间的总相图；(3)研究了不同平均链长和刚度多分散体系的吸附等温线和吸附-描述相变；(4)研究聚合物溶液的密度分布和结构与吸附表面距离的函数关系；(5)杂质对体系热力学和结构性质影响的研究。该问题具有重要的实际意义，因为它在润滑、粘附、表面保护等技术方面具有广泛的意义。聚合物吸附在胶体颗粒的表面，导致胶体悬浮液的（立体）稳定，这对染料的生产是重要的。材料理论方面的研究实现了推进科学的计划目标，使美国和保加利亚的顶尖专家能够在共同感兴趣和能力强的领域结合互补的人才和集中研究资源。

This proposal, "US-Bulgaria Cooperative Research on Computer Simulations of Polydisperse Polymer Systems," will be carried out by Dr. David P. Landau, University of Georgia and Dr. Andrey I. Milchev, University of Sofia. It envisages an ambitious program of research, designed to shed light on the complex cooperative behavior of a polydisperse system of semiflexible polymer chains in the presence of an adsorbing surface. Since the thermodynamic properties of such a system are so far largely unknown, the researchers believe that in a collaboration of three years they can produce a sufficient number of results in order to get a complete picture of the phenomena in question. The program of research should focus on: (1) Determination of the order of the disorientation phase transition in 2D; (2) Establishment of a total phase diagram in the multiparameter space of the energy interactions, temperature and density; (3) Investigation of adsorption isotherms and the adsorption-description phase transition for polydisperse systems with different average chain length and stiffness; (4) Study of the density profile and the structure of the polymer solution as a function of the distance from the adsorbing surface; (5) Investigation of the impact of impurities on the thermodynamic and structural properties of the system. The problem is of major practical importance since it has broad implications in lubrication, adhesion, surface protection, etc. technology. Polymers, adsorbed at the surface of colloid particles, lead to (steric) stabilization of the colloid suspension which is important for dyes production. This research in materials theory fulfills the program objective of advancing science by enabling leading experts in the United States and Bulgaria to combine complementary talents and pool research resources in areas of strong mutual interest and competence.