Computer Simulations of the Thermodynamic and Phase Diagrams of Polymeric Systems

聚合物系统热力学和相图的计算机模拟

• 批准号: 9311915
• 负责人: Sanat Kumar
• 金额: $ 38.2万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-01-15 至 1998-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9311915&HistoricalAwards=false
• 关键词: Computer; Simulations; Thermodynamic; Phase; Diagrams

9311915 Kumar The primary focus of this research is to understand the practically important question of the miscibility of polymeric systems from a molecular view point. An argument is made that the bulk thermodynamics of polymeric systems are poorly understood at this time since they are strongly dependent on local aspects, such as chain structure, stiffness and packing, which are not captured accurately by coarse-grained polymeric theories. Consequently, computer simulation on realistic chain models would represent an accurate technique to capture the effects of local structure and unpacking on thermodynamics properties. In addition to PVT equation of state properties, which can be obtained through standard computer simulation methods, newly proposed techniques will be used to enumerate the thermodynamic properties, especially the phase behavior, of these systems. In parallel the effect of film thickness on the phase separation in ultrathin polymer blends films will be studied. It is emphasized that a good understanding of this fundamentally important physical phenomenon is predicated on understanding, not only the surface behavior of polymeric systems, but also the bulk thermodynamics. This issue has already been studied in some detail from a theoretical viewpoint and experimental investigations are currently in progress. Finally, a good understanding of this situation also requires knowledge of the steric penalty associated with confining molecules near surfaces, and these aspects will be examined through a study of the alignment of liquid crystalline molecules in the vicinity of flat surfaces. ***

9311915库马尔这项研究的主要重点是从分子的角度理解聚合物体系的可混性这一实际重要的问题。有人认为，目前对聚合物体系的整体热力学了解很少，因为它们强烈依赖于局部方面，如链结构、刚性和堆积，而粗粒聚合物理论不能准确地捕捉到这些方面。因此，对真实链模型的计算机模拟将代表一种准确的技术来捕捉局部结构和拆分对热力学性质的影响。除了可以通过标准计算机模拟方法获得的PVT状态方程之外，新提出的技术还将被用来列举这些体系的热力学性质，特别是相行为。同时，还将研究薄膜厚度对超薄聚合物共混膜相分离的影响。我们强调，要很好地理解这一基本的重要物理现象，不仅要了解聚合物体系的表面行为，而且要了解整体热力学。这个问题已经从理论上进行了较详细的研究，目前正在进行实验研究。最后，要很好地理解这种情况，还需要了解与限制分子靠近表面有关的空间位阻，这些方面将通过研究液晶分子在平面附近的排列来检验。***