PDMS复合膜原料体系的基本力学热力学性质与乙醇丁醇渗透汽化行为之间的关系

In order to cope with energy crisis, separation of ethanol and butanol from fermented biomass is a major approach in a continuous or intermittent fermentation system. It is an extremely significant subject to recover alcohol from fermentation broth consecutively at a low cost. Pervaporation via PDMS membranes is the most promising technique recently. However, the field is seriously restricted for a lack of relative theories that can indicate the relationship among material properties, preparation parameters and separation performances. Therefore, we plan to study the inherent relations systematically through this project. According to Flory-Rehner and Bueche theories, mechanic parameters will be introduced for which closely interrelate with membrane materials including crosslinking agents and powder additives, molecular aggregate state and membrane swelling degree caused by permeation solutions. Important mechanical and thermodynamic parameters will be measured detailed and selected to analyze the connection between composite membrane material properties and alcohol permeation performances. Two main problems will be solved: first, IGC, Hanse solubility and solvation probe methods are used to determine appropriate dispersion, acid-base, hydrogen, polar forces and interaction of these forces with alcohol and water, respectively; then limited swollen of separation layers induced by support membranes will be investigated innovatively. The purpose is to reveal and predict PDMS membrane behavior through basic thermodynamic and mechanical data which can be descript independently and measured easily, and establish a model related with the separation behavior to them, and test the theories thoroughly. This work will be effective reference for the development of alcohol/water separation membranes, and more than 10 SCI articles will be published.

以生物质为原料经间歇或连续发酵制乙醇丁醇是应对能源危机的主要途径，如何低成本将醇从发酵液连续分离是有意义的课题。PDMS渗透汽化膜技术很有前景，但缺少联系材料性质、制备参数与性能间的理论是制约该领域的关键因素。课题组拟系统研究并深入认识这些内在关系。据Flory-Rehner及Bueche理论，拟引入力学参数，因其与膜材料（含交联剂、粉末助剂）分子聚集态及膜溶胀等紧密相关。将多角度、详细测定并选出某些力学、热力学量后分析复合膜原料性质与醇渗透间的关系。欲解决两个主要问题：一是用IGC、Hansen溶解度、溶剂化探针法测定出合适的色散、酸碱、氢键、极性力及与醇水间作用；还将创新性的探究支撑膜引起的分离层受限溶胀问题。目的是最终用能独立描述、易测量的基本热力学及力学量揭示、预测PDMS膜行为，建立分离行为与它们间的关系并检验理论。该工作对开发醇水分离膜具有参考价值，将发表SCI论文10篇以上。

课题组以正己烷与正庚烷为溶剂、二月桂酸二丁基锡为催化剂、正硅酸乙酯为交联剂、甲苯为抽提剂、5种数均分子量的端羟基型聚二甲基硅氧烷（PDMS）为前驱体，详细研究了前驱体的分子量与含量、交联剂与催化剂含量、溶剂类型、交联温度等有关材料性质、制备工艺参数与交联膜性能之间的关系。选定乙醇、水、乙醇/水混合物为表征膜与液体间相互作用的体系。通过测定甲苯抽提后交联膜的杨氏模量、平衡溶胀度、接触角、渗透通量、分离指数等参数来反映膜的基本性能。还详细研究了多种硅烷偶联剂的分子结构对交联膜性能的影响及分子机理。研究了前驱体的Hansen溶解度参数测定问题以及溶解度参数中各分量值对于膜性能的影响关系。研究了以纳米二氧化硅粒子和多孔分子筛粉末为改性剂时所制复合膜的性能及影响机理，以及超滤支撑底膜的制备条件及支撑底膜对复合膜性能的影响。最后还研究了交联膜杨氏模量、材料的溶解度参数与膜分离性能之间的关系。通过这些研究得到的重要结果为：从交联膜的杨氏模量看，最佳体系应由数均分子量为35.5 K的前驱体、5 wt%的交联剂、3 wt%的催化剂构成。用于改性的硅烷偶联剂的非水解基团与溶剂的溶解性较差时，制备出的混合膜的杨氏模量就低。在两类差值数据之间存在高度的线性相关性，这种相关性表明偶联剂的非水解基团与溶剂之间的热力学相容性决定了交联混合膜的力学性质。对于交联膜与极性溶胀液体之间的作用，是液体的极性参数差别决定了膜的溶胀度。所提出的改进Washburn方法能够准确的测定出粉末材料的色散表面自由能。用适当的硅烷偶联剂处理后的沸石粒子能够显著提升复合膜的分离性能。以较疏水的聚偏氟乙烯或者聚醚砜为材料制备的支撑底膜能够制备出性能很好的复合膜。以上这些研究结果对于理解与指导聚二甲基硅氧烷渗透汽化膜的制备具有重要参考价值。课题组一共发表学术研究论文15篇（其中SCI论文11篇、EI论文1篇、中文核心期刊论文3篇），出版学术专著1部。