Thermodynamic and Kinetic Control of Adsorption in Complex Fluids

abstractcts - 0001526 - i。大而复杂颗粒的吸附在大量重要的工艺过程中起着关键作用。例如：1)蛋白质吸附的控制是生物相容性材料分子设计的基础。2)蛋白质在给定构象表面的优先吸附对生物传感器的设计至关重要。3)沥青质聚集体吸附在岩石或输油管道上，给石油的开采和运输造成严重问题。4)表面活性剂和表面活性剂聚集体的吸附过程在降低界面张力和使用表面活性剂作为洗涤剂方面是重要的。了解决定吸附行为的分子因素对于合理设计具有所需性能的材料是必要的。这也是一个非常重要的基本问题，它需要理论方法的发展，能够在分子水平上描述在非均匀环境中具有内部自由度的分子的复杂混合物。粒子的大小意味着巨大的能量尺度，因此在许多情况下，该过程由其动力学行为主导。因此，挑战在于开发可靠的理论方法来描述分子水平上的平衡和动力学吸附。此外，这些方法应该弥合从原子到宏观的时间和长度尺度的差距。例如，在如此大的时间尺度下，吸附过程尽可能保持分子细节。最近发展的一般理论方法使研究链分子和蛋白质混合物的结构和热力学性质成为可能。该理论的预测已被证明是在极好的定量一致的平衡吸附等温线的蛋白质与接枝聚合物的表面。本文提出推广这种分子方法来研究多组分混合物、带电体系和非平衡体系。也就是说，扩展了研究吸附动力学的方法。此外，该计划还包括在各种系统中使用传统的模拟方法，蒙特卡罗，分子动力学和布朗动力学，其中计算复杂性不会使计算过于漫长，以检查动力学分子方法的有效性。通过这种方式，将获得一个理论方法的层次结构，这将使研究吸附过程中涉及的平衡和动态。这些方法将服务于双重目的：1)弥合原子和宏观描述之间在时间和长度尺度上的差距。这是一个重大的理论挑战，将为这些复杂系统的行为提供基本的理解。2)在这项工作中开发的方法也将被用于建立一个数据库，以了解如何根据所需的材料特性控制复杂颗粒的吸附。更明确地说，将研究系留聚合物层（包括聚电解质）减少颗粒吸附以选择性吸附所需颗粒的能力。这种理解将与实验合作者一起用于合理设计生物相容性材料、药物载体、生物传感器和增溶剂。这项工作的发现也有望对其他应用的材料设计产生重大影响，例如色谱，石油运输和洗涤剂。具体需要研究的问题有：1)将分子理论推广到三维，并与全模拟研究进行比较。2)包涵静电相互作用及其对大颗粒和蛋白质吸附的影响。(3)吸附动力学的系统研究。(4)构象变化对蛋白质吸附动力学和热力学行为的影响。(5)蛋白质混合物吸附的热力学和动力学行为。

ABSTRACTCTS-0001526I. SzleiferPurdue UniversityThe adsorption of large and complex particles plays a key role in a large number of important technological processes. For example: 1) The control of protein adsorption is fundamental in the molecular design of biocompatible materials. 2) Preferential adsorption of proteins on surfaces in a given conformation is of primary importance for the design of biosensors. 3) Asphaltene aggregates adsorb on rocks or oil pipes creating serious problems for the recovery and transport of oil. 4) Processes involving adsorption of surfactants and surfactant aggregates are important in the reduction of interfacial tension and the use of surfactants as detergents. The understanding of the molecular factors that determine the adsorption behavior are then necessary for the rational design of materials with desired properties. This is also a very important fundamental problem that requires the development of theoretical approaches that are able to describe at the molecular level complex mixtures of molecules with internal degrees of freedom that are in inhomogeneous environments. The size of the particles implies large energy scales and thus in many cases the process is dominated by its kinetic behavior. Thus, the challenge is to develop reliable theoretical approaches that can describe the equilibrium and kinetic adsorption at the molecular level. Furthermore, these approaches should bridge the gap in time and length scales from atomistic to macroscopic. For example, adsorption processes in that huge time scale keeping maximal possible molecular detail.A recent developed general theoretical approach enables the study of the structural and thermodynamic properties of mixtures of chain molecules and proteins. The predictions of the theory have been shown to be in excellent quantitative agreement for the equilibrium adsorption isotherms of proteins on surfaces with grafted polymers. Here it is proposed to generalize this molecular approach to study multicomponent mixtures, charged systems and systems out of equilibrium. Namely, to extend the approach to study kinetics of adsorption. Further, the plan includes the use of conventional simulations methodologies, Monte Carlo, molecular dynamics and Brownian dynamics in a variety of systems where the computational complexity does not make the calculations prohibitively long, to check the validity of the kinetic molecular approach. In this way a hierarchy of theoretical methods that will enable the study of the equilibrium and dynamic involved in the adsorption process will be obtained. These approaches will serve the dual purpose of: 1) Bridging the gap in time and length scales between atomistic and macroscopic descriptions. This is a major theoretical challenge that will provide fundamental understanding of the behavior of these complex systems. 2) The approaches developed in this work will also be sued to build up a database for the understanding of how to control complex particle adsorption depending on the desired properties of the materials. More explicitly, the ability of tethered polymer layers, including polyelectrolytes, to reduce particle adsorption to selectively adsorb a desired kind of particle will be studied. This understanding will be used in conjunction with experimental collaborators in the rational design of biocompatible materials, drug carriers, biosensors and solubilizers. The findings from this work are also expected to have a major impact on the design of materials for other applications, such as chromatography, oil transport and detergency.Specific problems to be studied: 1) Generalization of the molecular theory to three dimensions and comparisons with full simulation studies. 2) Inclusion of electrostatic interactions and their effect on large particles and protein adsorption. (3) Systematic study of the kinetics of adsorption. (4) Effect of conformational changes on the kinetic and thermodynamic behavior of protein adsorption. (5) Thermodynamic and kinetic behavior on adsorption of proteins mixtures.