Synthesis of Ionic Liquids, Solubility for Wood and Its Application for Graft Copolymer with Acrylamide

Abstract

With the increasing awareness in sustainable development of environmental protection, there is a keen aspiration in exploring natural recoverable and environment-friendly materials [1]. Wood is a typical abundant natural material which is environment-friendly and easily-obtained. Cellulose, hemi-cellulose and lignin are the main components of wood powder which build the spongy three-dimension structures [2]. The poor solubility of wood powder in normal solvents strongly limits its application, hence it is important to find out environment-friendly solvents for wood powder. The conditions of using conventional method to dissolve wood in solvent such as phenol or polyhydric alcohols were very strict and the original structures of wood were destroyed which results in the loss of mechanical properties [3, 4]. In contrast, ionic liquids which were known as green solvents for cellulose [5-9], can partly dissolve wood powder, and improve the reactivity due to the structural laxity [10-12]. The applications of ionic liquids ranged from chemical synthesis, biological catalysis, preparation of functional materials, etc. [13-19]. In addition, as a newly-developed technique which was widely used in various chemical areas, microwave can be applied in dissolving wood powder as a new and high efficient method. Regarding the importance in preparing environment-friendly polymer materials from natural resources, studies of lignin were reported from several countries such as U.S., Japan, etc for decades. Polyacrylamide, enjoying the reputation of “hundred industry assistants” is used in various fields. But production cost is very high for its application. It has been of inevitable trend and broad prospects to develop multi-functional lignin flocculant using inexpensive lumber [20, 21]. Meanwhile, copolymerizations of lignin or cellulose with vinyl monomers in aqueous medium were reported [22-25], which have the shortages of low conversion of the polymerization, instable final product and difficulty in controlling the reactions. To overcome the disadvantages stated above, here, we report the synthesis of a novel flocculant with wood and acrylamide (AM) by graft copolymerization (AM-g-wood) in ionic liquids in which wood powder was used as alternative to lignin, which can introduce the new concepts of utilizing natural recoverable resources. Besides, graft copolymer of AM-g-wood as a novel modified flocculant, whose production cost was decreased greatly in this research, also could be widely applied in areas such as water treatment, petrochemical industry, mineral processing, papermaking and so on. The related work is being researched.