聚合物发泡与多孔功能材料的研究与应用进展

Progress on research and applications of polymeric foams and porous functional materials

封闭独立(闭孔)和相互贯通(开孔)的孔洞结构可在聚合物基体中引入均匀分布的气体和固相/气相界面,这赋予了聚合物材料轻量化的优势和新的功能性.过去的十年中,我们课题组围绕多相多组分聚合物微孔材料的制备、有序孔结构的构筑、聚合物发泡和多孔材料的功能应用、聚合物创新发泡方法等开展了系统研究,突破了超临界流体间歇发泡技术的关键技术瓶颈并研制了核心加工装备,实现了聚合物发泡材料在运动防护等多个领域的产业化应用.本文首先介绍了孔洞结构对聚合物材料性能的影响和本课题组已开展的制孔方法及聚合物体系,重点介绍了热塑弹性体和生物可降解聚合物的超临界流体发泡行为,讨论了微孔结构的调控方法,阐明了闭孔结构实现材料轻量化和提高材料弹性的规律.其次,介绍了聚合物复合多孔材料的制备方法,阐述了多孔结构对聚合物材料的电磁波屏蔽性能、液体吸附性能、太阳能蒸发效率的影响规律及作用机制.最后,对聚合物发泡与多孔功能材料的发展进行了展望.

Polymeric foams and porous materials are lightweight polymeric materials with a porous structure,also known as polymeric foams.Depending on the connectivity of the pores,polymeric foams can be classified into closed-cell and opencell structures.The properties of open/closed-cell polymeric foams are determined by the polymer matrix,pore structure,and gas/cell wall interface characteristics.The diverse polymer matrices and rich pore structures endow polymeric foams with numerous functions,making them play a vital role in daily life and industrial production.Supercritical fluid physical foaming is a method for preparing polymeric foams using nitrogen or carbon dioxide supercritical fluids as physical foaming agents.This technology has gained increasing attention in academia and industry due to its environmentally friendly process,uniform and tiny cell structure of the prepared foam materials,and diverse preparation methods.Nonetheless,the foam materials obtained by supercritical fluid physical foaming are mainly closedcell.The preparation of polymer porous materials with an open-cell structure can be achieved by selecting phase separation and ice templating methods.With the help of phase separation,polymer porous materials can be composited with more nanofillers to achieve superior functionality.This review summarizes the systematic work of the research group on the preparation of polymer/graphene oxide composite porous materials by phase separation.Up to 10wt%–30wt%of graphene oxide can be uniformly or selectively dispersed in the polymer porous materials through phase separation,endowing the polymer composite porous materials with good electromagnetic shielding effectiveness and electromagnetic wave absorption characteristics.This is beneficial for reducing electromagnetic wave leakage and the resulting secondary pollution problems.The porous structures obtained by physical foaming and phase separation often exhibit a relatively uniform distribution,but the orientation degree of the cell structure is low,and the pores cannot be interconnected.Directed freezing technology based on the ice templating method provides a way to obtain highly ordered pore structures in polymer systems.With the help of directed freezing technology,ordered porous foams with a single scale can be constructed,exhibiting excellent liquid adsorption performance.These ordered porous foams have tremendous application prospects in areas such as rapid liquid adsorption,active liquid transportation,and oil-water separation.Driven by the“dual carbon-driven high-quality development”strategy,low-carbon foaming technology using supercritical fluids as green foaming agents has gained market recognition.A large number of related research and development products have continuously moved from the laboratory to the market,and polymer foams and porous materials have received more attention.However,there are still many problems and challenges in the field of polymer foaming and porous materials that need to be urgently addressed:(1)Focusing on evolving application scenarios,developing polymer foam materials with specific geometric shapes(such as polymer microporous films,polymer microporous fibers,etc.)and special functions(such as low dielectric properties to meet 5G and 6G applications),and conducting in-depth research on material structure-property relationships to meet material application requirements;(2)innovating pore-forming methods and developing high-performance polymer foams and porous functional materials with the help of biomimetic design principles;(3)fully utilizing the advantages brought by the pore structure to polymeric materials and developing multifunctional and smart materials.