胶体在聚合物中自组装及凝聚成核统计力学研究

Understanding of the process of self-assemble and nucleation of colloid in polymer system is the main challenge in softmatter Science. In this work, we will study the process using the statistical mechanics theory.At first, we apply the polymer reference interaction site model to derive out the depeletion poential induced by the polymer, and use it to construct the basic density functional model, and calculate the density porfile of colloid and polymer around a colloid particle. The density functional method is then extended to form a dynamic density functional equation, where the Brownian motion equation, the depletion potential, and the solvent potential are integrated.The process of self-assemble of colloids is then investigated systematically. On the other hand, the above density functional method is applied to study the microphase seperation as well as the liquid-solid phase behavior based on a new equlibrium algorithm.Paricularly,the entropy variation of both liquid and solid need to be further analyzed in consideration of the long-range density fluctuation of second order phase transition within the framework of density functional.To analyze the nucleation process of colloids in polymer, a three-dimensional density functional model will be construct for both homogenous and heterogeneous systems,and to calculate the free energy barrier and the radius of nuclei.By combining the polymer reference interaction site model and density functional theoretical method, we will develop a new theoretical model to go deep into the colloid and poymer system, where the strcutre and propierties of colloid and polymer are studied simultaneously.Finally, some corresponding experiments about the self-assemble process will performed to test the reliability of some theoretical predictions

胶体聚合物体系自组装及凝聚成核过程，是软凝聚态领域有关结构和相变研究的前沿挑战性问题。课题从微观分子层面出发，运用统计力学理论展开系统研究。应用高分子积分方程理论获得聚合物对胶体颗粒的耗损力，以此作为胶体颗粒间相互作用力建立密度泛函理论模型；综合考虑溶剂力/外力等因素，建立动力学密度泛函方法，研究胶体颗粒在聚合物中的自组装行为；应用密度泛函方法，研究胶体的微相分离和液固相平衡，重点研究解决平均场理论在计算液固平衡中出现熵奇异问题；根据固体颗粒成核特性，建立受限条件下的三维密度泛函模型，分析成核自由能垒和临界成核半径；充分考虑胶体和聚合物的特性，建立受限条件下胶体和聚合物混合积分方程，并引入桥函数校正，获得精确的胶体和聚合物二元体系的密度分布及自由能泛函；相对胶体/聚合物/溶剂自组装体系开展定量测定，以检验理论模型。

本项目从胶体颗粒与聚合物基团相互作用出发，考虑实际聚合物链不同基团化学特性和空间拓扑结构，构建了分子层面的、能描述实际各种合物体系的密度泛函理论（DFT）模型，包括含侧链、支链、星型链的均聚物、嵌段共聚物和共混聚合物，确定了不同拓扑结构聚合物链构象熵的定量表征，通过相关实验建立了理论模型的可靠性；构建了胶体颗粒/聚合物体系的DFT模型，解决了颗粒-聚合物基团高度非对称作用的理论建模问题，研究了不同聚合物颗粒复合体系在体相和受限空间（表面）的结构和性质，通过相关实验测试检验了理论模型；构建了关于不同晶格点阵结构的DFT表达，通过不同晶体结晶成核及晶液界面结构和性质的理论表征并与实验结果比较，检验了多种晶格点阵结构DFT模型的可靠性和准确性；构建了颗粒/聚合物/溶剂复合体系的动力学密度泛函理论（DDFT）模型，弄清了溶剂和聚合物链影响颗粒聚集过程的微观机理，分析了聚合物链运动规律和溶剂力对颗粒和聚合物链运动的粘滞效应，为颗粒自组装机理研究作了充分的理论准备；通过纳米颗粒自组装行为实验研究，一是验证了理论模型预测的可靠性，二是在理论指导下，探索了不同体系中如何高效率地实现有序自组装过程，为二维和三维有序材料合成打下了坚实的理论和实验基础。