探索原位研究聚合物超薄膜黏弹性及其分子运动的新方法

项目名称： 探索原位研究聚合物超薄膜黏弹性及其分子运动的新方法

项目编号： No.21504081

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 数理科学和化学

项目作者： 左彪

作者单位： 浙江理工大学

项目金额： 21万元

中文摘要： 聚合物薄膜具有与本体不同的分子运动行为。聚合物薄膜分子运动对于聚合物纳米材料的性能调控及成型、加工等具有重要意义，是当前高分子物理领域的研究热点。目前，聚合物薄膜分子运动的物理机制仍不清楚；不同研究方法的结果不能很好的统一。发展研究聚合物薄膜分子运动的新方法是当务之急。本项目首次提出通过研究聚合物薄膜表面润湿脊（wetting ridge）形成动力学，原位研究薄膜黏弹性及分子运动行为。项目研究与聚合物不相容的液滴在聚合物表面润湿脊的形成与生长过程及其与温度、分子量等的关系；利用蠕变模型分析润湿脊发展过程，关联润湿脊线性增长速率、特征松弛时间、特征形变温度等特征参量与聚合物黏弹性及分子松弛的本质关系，发展一种原位测量高分子薄膜黏度、松弛时间、黏流温度的新方法，奠定其理论基础。并利用该法研究膜厚、温度、分子量、基底性质对薄膜分子运动的影响，探索一维受限聚合物薄膜分子松弛的物理机制。

中文关键词： 聚合物薄膜；黏弹性；分子运动；纳米受限效应；玻璃化转变

英文摘要： Thin polymer films have striking dynamical properties that differ from their bulk counterparts. Optimizing the functionality of nano-materials and micro-manufacturing of polymer nano-devices require a broad understanding of the dynamics of polymer chains under confinement in the thin-film geometry. The molecular motion in nano-confined systems is a relatively new topic and object of intense scientific debate. Although an amount of knowledge has been achieved, no generally accepted theory exists and the dynamics related with thin polymer films remain a pending problem in polymer condensed matter research. Consequently, there is a great demand for novel approaches based on various mechanisms to characterize the viscoelasticity and molecular motion of polymer thin film. This project firstly presented an entirely new method to in-situ study the viscoelasticity and molecular motion of polymer thin film by researching the wetting-ridge growth dynamic. The evolution of wetting ridge on polymer film surface with different molecular weight and at various temperatures by a liquid droplet which is thermodynamically immiscible with the polymer was systematically investigated in this project. The creep model is employed to analyze the development process of wetting ridge, and several quantitative parameters such as wetting ridge linear increment velocities (k), characteristic relaxation time (τ*) and characteristic deformation temperature (T*) are put forward to describe the growth dynamics of wetting ridge. The inherent relationships between these parameters and viscoelasticity, molecular relaxation of polymer films are explored, and the physical meanings of these parameters are clarified. The aim of this project is to develop an original method for in-situ characterizing the viscosity, segmental relaxation time, viscous flow temperature of thin polymer films, as well establish the theoretical foundation of this method. Meanwhile, the effects of film thickness, temperature, molecular weight and substrate chemistry on molecular mobility of thin polymer film were investigated using the developed method, for seeking the physical mechanism of the molecular motion of thin polymer films. This study would provide a new method measuring the molecular motion of thin polymer film; as well deepen our understanding of polymer chain motion under geometrical confinement.

英文关键词： thin polymer film;viscoelasticity;molecular motion;nano-confinement effect;glass transition