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”的提案将由佐治亚大学的David P.Landau博士和索非亚大学的Andrey I.Milchev博士共同完成。它设想了一个雄心勃勃的研究计划，旨在阐明半柔性聚合物链多分散系统在吸附表面存在时的复杂合作行为。由于到目前为止，这样一个系统的热力学性质基本上是未知的，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。研究程序应集中在：(1)确定二维无定向相变的顺序：(2)在能量相互作用、温度和密度的多参数空间中建立总相图；(3)不同平均链长和不同刚性的多分散体系的吸附等温线和吸附描述相变的研究；(4)研究了聚合物溶液的密度分布和结构随离吸附表面距离的变化；(5)研究了杂质对体系热力学和结构性质的影响。这一问题在润滑、粘着、表面保护等技术中具有广泛的应用价值，具有重要的现实意义。聚合物吸附在胶体颗粒表面，导致胶体悬浮液的(空间)稳定，这对染料生产是重要的。材料理论的这项研究通过使美国和保加利亚的顶尖专家能够结合互补的人才并在相互感兴趣和能力很强的领域汇集研究资源，实现了推进科学的计划目标。

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.