以离子液体为介质的纤维素加工与功能化

纤维素作为自然界中储量最大的天然高分子,被认为是未来世界能源与化工的主要原料.但由于分子链间存在丰富氢键网络以及高度结晶的聚集态结构特点,天然纤维素不熔化、难溶解,造成纤维素的加工极其困难,纤维素材料的传统生产工艺复杂且污染严重,极大限制了纤维素材料的广泛应用.近年来,人们发现一些特定结构的离子液体能够高效溶解纤维素,为纤维素的加工和功能化提供了新的多用途平台.本文从"溶解纤维素的离子液体、纤维素溶解机理与溶液性质、以离子液体制备再生纤维素材料和以离子液体为介质合成纤维素衍生物"4个方面详细介绍了本课题组在此领域的研究进展.

Processing and Functionalization of Cellulose with Ionic Liquids

As the most abundant natural polymer on the earth,cellulose has been considered as the sustainable raw material of energy and chemical engineering in the future.However,because of the strong hydrogen bonding network,cellulose is unmeltable and insoluble in conventional solvents,which limits its wide utilization.Effective utilization of cellulose-based resources is becoming a hot spot in chemistry,chemical engineering and material science fields.Recently,certain ionic liquids exhibited excellent dissolving capability for cellulose,which provides a new and versatile platform for cellulose processing and functionalization.By using ionic liquids as the solvents,a variety of cellulose-based materials,including fibers,films,hydrogels,aerogels and composites have been fabricated successfully and efficiently.Among them,regenerated cellulose fibers and films with outstanding mechanical properties are being produced on the pilot scale.In addition,almost all conventional cellulose esters,a variety of novel and functional cellulose esters,especially partially and regioselectively substituted cellulose esters,and cellulose graft copolymers have been successfully synthesized using ionic liquids as reaction media.In this review article,we will summarize our research work on cellulose dissolution,processing,homogeneous derivatization and graft copolymerization with ionic liquids.We first introduce the ionic liquids with good capability for dissolving cellulose.Then,the dissolution mechanism and dissolution process of cellulose in ionic liquids,and the physical properties of cellulose/ionic liquidssolutions are also discussed.Based on the understanding of the dissolution and regeneration process of cellulose in ionic liquids,our research progress on preparation of various regenerated cellulose-based materials in ionic liquids are described.The homogeneous derivatization and graft copolymerization of cellulose to make novel functional cellulose materials are also summarized.Finally,a brief outlook for future opportunities in advancing this area is also depicted.It is hoped that this review will draw more attention of scientists and engineers to this relatively new and exciting research field.