复杂高分子液体薄膜的稳定性及其结构形成动力学

The thin polymer films have a high application potential on the protecting coating, lithography, the choosing filter film, photoelectricity apparatus, data storage and microreactor so on. However, the stability of the thin polymer film is an important factor to influence its application. Thus, in recent years many scientists have widely investigated the dewetting behavior of the thin polymer film. Besides, the thin polymer film is also an ideal mode system on the study of the low dimensional physics because the vapor pressure of the polymer is low and the mobility of the polymer is slow. Thus, this is helpful for the development of the low dimensional condensed physics. In a word, the study of the dewetting behavior of the thin polymer film has an important significance on the fundamental study and the technological applications.However, many applied polymer films is not single phase but mutiphase and multicomponent system. Till now the instability and dynamics of the complex polymer film is still open. Here, this project aims at the investigation of dynamics and instability of complex polymer film. We choose two kinds of model systems, blend and block-copolymer film with weak and strong segregation. Firstly, we monitor evolution of the structures by in situ atomic force microscopy (AFM), in situ X-ray photoelectron spectra (XPS), grazing incidence small-angle X-ray scattering (GISAXS) and so on. Secondly, we investigate the interplay between phase separation and dewetting; effect of slippage and viscoelasticity on the moving front of dewetting and rim instabilty; compared with melting film, understanding solvent induced dewetting mechanism. In addtion, we will establish kinetic Monte Carlo, combining Brwonian Dynamics simulationa and Self-consistent field respectively. According to theory and simulation, we explore early stage and the mechanism of the coupling behavior. Finally we will try to suggest a universal model to discribe their interplay behavior, which will be helpful for control of morphology and structure of complex polymer film.

本基金申请旨在通过正空间（原子力显微镜和光学显微镜等）和倒易空间（同步辐射掠入射X-光散射）相结合的原位实验手段，以强和弱相分离的混合物及嵌段共聚物作为模型体系，在线跟踪复杂高分子液体薄膜中、后期阶段的结构演变动力学过程，探讨在不同基底、组成和膜厚条件下的（微）相分离和去润湿的耦合行为；阐明不同机理去润湿【不稳机理和成核机理】与（微）相分离的耦合机制；揭示不同耦合机制下的滑移效应和薄膜粘弹性质对结构动力学及其标度行为的影响规律。同时根据实验体系构建模拟模型，利用动态蒙特卡洛分别与布朗动力学和自洽场相结合的方法，一方面探讨（微）相分离与去润湿耦合动力学和热力学的机制，另一方面微观尺度阐明复杂动力学过程的前期和早期阶段。综合实验和模拟，全面评估从前期、早期到中后期的动力学演变规律，提出具有一定普适性的模型描述复杂高分子液体薄膜稳定性及其结构形成动力学规律，为薄膜结构调控提供科学依据和理论指导。

受限情况下复杂高分子薄膜稳定性及结构形成动力学机制在众多应用中扮演了关键性角色，然而由于受限条件下高分子微观链结构信息（特别是动力学信息）以及制膜工艺条件对薄膜初始状态影响规律的匮乏和多相多组分高分子薄膜在制备及使用过程中涉及的溶解、溶胀、相分离、去润湿及其复杂的耦合行为，其微观机制的系统阐释面临巨大挑战。为此，本项目通过模拟和实验相结合的方法进行了系统研究。一方面，建立模拟方法，提出了“与它链相互作用对数”参量定量评估高分子链动力学受限程度，取代前人的唯象参量（膜厚/无扰回转半径），进而发现并揭示了链扩散动力学随膜厚变化的四种不同敏感性的根源在于链动力学受限和缠结效应竞争；系统阐释了基底和高分子相互作用对受限高分子动力学的影响规律，澄清了前人获得“受限导致高分子运动快慢”矛盾结论的成因，进而探讨分子量的多分散性对受限高分子动力学的影响，并阐明了分子的约束释放效应的分子机理。另一方面，通过模拟与实验相结合的方法，阐明了热退火导致微观分子构象变化，进而引起链跟基底吸附行为不同是去润湿不稳定边波长不同的成因；提出了不同拓扑结构高分子去润湿动力学不同的根源是去润湿和吸附之间竞争所致；搭建原位椭偏仪和光学显微镜连用装置，首次阐明了溶剂加工导致不同分子量高分子薄膜的去润湿动力学行为不同的根源在于溶剂吸附层是否形成所致。系统考察了复杂高分子体系中组成、薄膜厚度、溶剂选择性等因素对其相行为及耦合机制的影响规律。最后，项目组将上述研究所得规律应用到高分子物理研究和功能材料的有效设计与构筑领域。一方面，通过调控薄膜厚度精确控制去润湿的程度，获得了具有“Crack”结构的单层高分子薄膜，以此为基础，阐明了环带球晶形成的机理；另一方面，通过系统调控高分子共混薄膜的稳定性，建立了通过去润湿构筑液滴阵列和多孔材料的新策略，并将所得材料成功应用到表面拉曼增强和分离领域，为功能材料设计提供了新思路。