Ab initio entangled polymer rheology: homopolymers, blends and copolymers

项目负责人：Schieber， Jay D.提案编号：1438700机构：伊利诺伊理工学院。该项目的重点是用多尺度计算方法研究纠缠聚合物的流变性。拟议的研究将确定在原子水平上计算所需的参数，以便提供关于各种软材料流变学的宏观尺度预测。纠缠聚合物在工业材料中具有巨大的经济影响，同时也影响着生物组织的力学。对这些动力学理解的任何重大进展都将对物理学、材料科学、生物物理学、生物学和工程学的许多分支产生重大影响。co- pi将生成一个用户友好的图形用户界面（GUI），并将其GPU代码提供给公众使用。这个代码将允许任何用户使用一个简单的桌面和显卡（不到1万美元）来预测线性、分支或交联纠缠均聚物在均匀流场中的任何共混物的线性或非线性流变。提出实现软物质弛豫时间为秒或分的首次从头算动态预测。从从头算开始，提出了一种分层的仿真结构。目标是对任何纠缠的均聚物链结构、任何分子量、任何结构和分子量的混合以及任何流场进行预测。所使用的均聚物模型是基于热力学的，并符合平均场理论。虽然目前可用的模型需要参数拟合和经验主义，但这项工作的智力成就，如果成功的话，是仅从原子知识预测纠缠均聚物的流变性，而不需要任何参数拟合。这一壮举可以通过使用将计算速度提高约12个数量级的技术来实现，从而在原子时间和宏观时间之间架起时间尺度的桥梁。

PI: Schieber, Jay D. Proposal Number: 1438700Institution: Illinois Institute of TechnologyThe focus of this project is on investigating entangled polymer rheology with a multiscale computationally approach. The proposed research will pin down the parameters needed to be calculated at the atomistic level, in order to provide macroscopic scale predictions about the rheology of a wide class of soft materials. Entangled polymers have tremendous economic impact in industrial materials, and also influence the mechanics of biological tissue. Any significant advance in the understanding of these dynamics will have substantial impact on many branches of physics, materials science, biophysics, biology and engineering. The co-PIs will produce a user-friendly graphical user interface (GUI) and make their GPU code available for public consumption. This code would allow any user with a simple desktop and graphics card (less than $1k) to predict the linear or nonlinear rheology of any blend of linear, branched or cross-linked entangled homopolymers in a homogeneous flow field.It is proposed to achieve the first ab initio dynamic prediction for soft matter that exhibits relaxation times of seconds or minutes. A hierarchical structure of simulations is proposed, starting from ab initio type of calculations. The goal is to make predictions possible for any entangled homopolymer chain architecture, any molecular weight, any blend of architecture and molecular weight, and for any flow field. The homopolymer model to be used is thermodynamically based and in accordance to mean-field theory. While currently available models require parameter fitting and empiricisms, the intellectual achievement of this work, if successful, is to predict the rheology of entangled homopolymers from atomistic knowledge only, without any parameter fitting. This feat can be accomplished with the use of techniques to speed-up calculations by about 12 orders of magnitude, allowing the bridging of the time scales between atomistic and macroscale times.