无机介质内嵌堵孔提高有机蒸汽脱水聚合物膜的耐溶剂性

Glassy polymer membrane is an efficient and compact separation element for dehydration of condensable organic gases. However, the organic vapors and their condensates can seriously swell the rubbery polymers for blocking the micro-defects of glassy dense selective layer. As a result, the membrane would be failure in dehydration selectivity along with the structural breakdown in swelling environments, that is a serious constraint to the actual applications. Therefore, the interfacial Sol-Gel process between liquid and gas phases is proposed in this project for blocking the micro-defects of selective layer, i.e., the localizable synthesis of stable inorganic silica particles in micro-defects. The as-prepared gas dehydration membrane is expected to behave with high solvent resistance. .The main innovation details: 1) the effective substitution of defect blocking materials, i.e., the tough inorganic particles rather than the elastic rubbery polymers are adopted to avoid material swelling; 2) the compatible change in defect blocking mode, i.e., the localizable synthesis in defects is replacing the general solution coating on surface, to improve mechanical strength and stability of composite structure, and also to upgrade gas permeation ability via eliminating surface resistance layer of blocking materials. In particular, mass transfer and hydrolysis reaction at the interface between liquid (organic amine solution) and gas (SiF4) phases in the nano-confined defect structure would be studied intensively, on the basis their synergistic effect is regulated to control the synthesis position of inorganic particles in micro-defects, with the object of preparing high-permeable solvent-resistant dehydration membranes. .In conclusion, the study in this project would bring about new preparation mechanisms and approaches for solvent-resistant gas separation membranes, which is very important to expand the application fields of membrane technology in chemical and engineering industries.

采用玻璃态聚合物膜对可凝性有机气体脱水，简单高效。然而，有机蒸汽及其凝液能溶胀选择层缺陷中的橡胶态堵孔材料，破坏复合结构，实际应用严重受限。本项目提出气-液相界面溶胶-凝胶反应，在缺陷孔中定位合成二氧化硅无机颗粒，弥补选择层的缺陷孔。创新性在于：改变了堵孔介质，用无机颗粒取代橡胶态聚合物，避免材料溶胀；改变了堵孔方式，选择层缺陷内定位合成代替表面溶液涂敷，构筑“内嵌式”堵孔，在显著提高复合结构强度、抑制剥离的同时，避免堵孔介质在膜表面形成附加阻力层，提高渗透性。本项目重点研究复合膜制备过程中狭小空间内硅源(气相SiF4)和水解环境(胺-水溶液)接触界面的传质和反应规律，探索相界面分子扩散与水解反应的协同耦合，调控无机颗粒的合成位置及其在缺陷孔中“限域”合成，提高聚合物脱水膜的渗透性和耐溶剂性。本研究将深化耐溶剂型气体分离膜的制备理论和技术途径，对拓展膜技术在化工领域的应用具有重要意义。

项目背景：可凝性有机气体脱水在化工、能源和医药等领域不可或缺。与吸收、吸附等传统方法相比，聚合物膜法脱水能耗低、适应性强、无需再生、维护方便。从分离性能角度看，聚合物膜完全满足上述脱水需求，但是传统聚合物脱水膜的堵孔涂层是橡胶态PDMS，在可凝性有机气体中寿命很短。综上，在避免可凝性有机蒸汽或溶剂溶胀破坏堵孔结构的同时，减小或避免复合涂层的传质阻力，成为研制高性能脱水膜急需解决的关键科学问题。. 研究内容：本项目提出基于相界面反应的复合结构制备新方法，在基膜缺陷孔中原位合成耐溶胀颗粒实现堵孔。通过相界面调控耐溶胀颗粒在缺陷中的合成位置和生长程度，在提高复合结构强度、抑制剥离破坏的同时，避免耐溶胀介质在膜表面形成致密层，减小渗透传质阻力，从而制备出气体渗透性能更高的耐溶剂型聚合物脱水膜。. 重要结果及关键数据：研制出沸石型咪唑框架ZIF-8堵孔的复合膜，JH2 = 3980 GPU，αH2/CH4 = 26.0，可以用于有机气体脱水（J. Membr. Sci. 2017, 541, 101-107）；建立铁离子络合+催化氧化的多巴胺（DA）聚合堵孔方法，利用PDA的粘附和交联性，实现涂层在非质子极性有机溶剂环境中的长期稳定性，液态溶剂中浸泡24小时无质量损失（ZL201611178888 .3；美国发明专利US Pat. App. 16/323,452）；基于耐溶胀膜的根本特征出发，建立具有梯度湿度空气环境的干湿相转化制膜工艺，消除相转化过程中致密功能层形成缺陷的根本原因，研制出无需堵孔涂层得非对称聚酰亚胺膜，致密功能层厚度减薄至80nm，相比于常规相转化工艺制备的膜，渗透性提高85%，选择性基本不变，并且在有机蒸汽环境中长期稳定（J. Membr. Sci. 2019, 577, 258-265）。. 科学意义：针对聚合物脱水膜在常见可凝性有机气体中溶胀破坏导致的失效问题，提出原位合成耐溶胀颗粒代替橡胶态聚合物涂层作为堵孔介质，提高堵孔复合结构的尺寸稳定性，同时通过反应相接面的调控，减少堵孔介质在膜表面形成致密层，减小渗透传质阻力。上述制膜理念为研制新型阻力复合膜提供了新方向，对拓展膜技术在化工领域的应用具有重要意义。