Synthesis Of Ionic Liquids And Functionalization Of Cellulose In Ionic Liquid

Cellulose is a representative natural polysaccharide and the most abundant organic substance on earth. It is renewable, biodegradable and can be used as promising materials for various useful products. With the increasing attention of environmental problems and global shortage of petroleum resources, a great number of researchers have been attracted by this natural substance as a central topic in polymer materials. Room temperature ionic liquids are a class of novel environment- friendly "green solvents", and recently, it has been discovered that some of them could be used as reaction medium because of their better dissolution of cellulose. For the sake of improving the utilization of cellulose, functionalization of cellulose and preparing cellulose composite materials have been carried out in ionic liquid. Polyurethane is a most important material with a broad variety of applications in industry. However, due to its difficult disintegration and incorporation to the environment, the polyurethane industry is facing environmental challenges.This dissertation is set out from synthesis of ionic liquids, research of solutions and regeneration of cellulose in ionic liquids. At the same time, prepolymers of polyurethane with terminated isocyano group react with cellulose in ionic liquids to prepare microcrystalline cellulose/PU. It could enable cellulose/polyurethanes materials to be applied as a developed material, and as a result, improve the utilization of cellulose in the future.The major results obtained in the study include as following:1. Four kinds of liquids, 1-butyl-3-methylimidazolium chloride([Bmim]Cl),1-allyl-3- methylimidazolium chloride([Amim]Cl),1-Carboxyethyl-3-methylimidazolium chloride and Gemini ionic liquids, have been synthesized in this study. It was found that [Bmim]Cl and [Amim]Cl were both powerful solvents, can be discovered in short time. 1-Carboxyethyl-3- methylimidazolium chloride and Gemini ionic liquids can not discover cellulose.2. The process of microcrystalline cellulose dissolution and regeneration in 1-butyl-3-methylimidazolium chloride([Bmim]Cl)has been studied. The results show that instead of any chemical reaction, the dissolution and regeneration of microcrystalline cellulose turns out to be a physical process. the crystal structure of microcrystalline cellulose was transformed from cellulose type-I to cellulose type-II after the process of its dissolution and regeneration in [Bmim]Cl. At same time, degree of crystalline was decline compare with microcrystalline cellulose. Compared with microcrystalline cellulose, the regenerated cellulose has a worse thermal stability, but more relict. SEM results show that regenerated cellulose film was not close-grained.3. In this research, three kinds of prepolymers terminated by isocyano group (-NCO) are synthesized by the reactions of polyol (N-220) with TDI, MDI and IPDI respectively at the same reaction conditions and the molar ratio of N-220 to diisocyanate. And then, the polyurethane prepolymers reacted with microcrystalline cellulose, which resolved in 1-butyl-3-methyl imidazolium chloride, a kind of imidazolium ionic liquid, to obtain a series of cellulose/polyurethane materials. The results show that for cellulose/PU materials, only a dispersive broad peak around 20.35°(2θ) was observed, the crystal structure of microcrystalline cellulose was destroyed. The result of TGA shows that cellulose/PU materials have satisfying thermal stability, and in the all four kinds of hybrids, the cellulose/PU-1, which prepared from cellulose and the PU prepolymer synthesized by TDI has the best thermal stability. cellulose/PU-1 which prepared from cellulose and the PU prepolymer synthesized by MDI has more relict.