Synthesis Of Cellulose Esters And Properties Study

The traditional polymeric materials have enriched greatly people’s daily life, but the disadvantages of their over-reliance on fossil resources and the environmental pollution arose because of their use have also been recognized. Biomass are bionewable and large available, and the use of them as renewable raw material for production of bioenergy, chemicals and materials has become of growing interest.Cellulose esters are extremely commercially important materials of biomass derivatives with a wide application in the field of plastics, film, textile, coatings, and pharmacy industries. The use of cellulose as raw material for synthesis of cellulose esters, it is the most abundant renewable natural biomass material. The cellulosic materials are also inexpensive, biodegradable, environmental friendly and have good mechanical properties, low density and so on. The design and preparation of materials using cellulose as raw material has become a trend of the future development.Based on the technology of biomass conversion in our laboratory, in this paper, with the dissolution of cellulose in a new mixed solvent system named reversible ionic liquids/DMSO, controllable, green and effective synthesis of cellulose esters has been successfully accomplished under the homogeneous conditions, and the structure-activity relationship of cellulose esters was revealed. The main research contents of the manuscript are divided as follows:1. Based on the dissolution of cellulose in a new mixed solvent,[DBUH][O2COCH3]/DMSO (XRILs=0.2), reactive behaviors of cellulose with fatty acid anhydrides have been studied, The effects of reaction time, temperature and molar ratio of anhydride/OHs on DS value of cellulose esters were investigated. The results showed that of cellulose acetate with a DS of2.41was achieved after only5min at80℃when the molar ratio of acetic anhydride to all of the hydroxyl groups (OHs) in solution is set to1.2:1. The structures and thermal properties of the obtained cellulose esters were characterized by means of nuclear magnetic resonance (NMR), fourier transform infrared (FT-IR) and thermogravimetric analysis (TGA).2. The reversible reaction of the hydroxyl groups with CO2in the presence of tetramethyl guanidine lead to full derivative dissolution of cellulose in DMSO, on which, the synthesis of various cellulose esters was studied. The structures of cellulose esters were confirmed by NMR and FT-IR, and their thermal properties was primary investigated by TG analysis. 3. The reversible reaction of the hydroxyl groups with CO2in the presence of tetramethyl guanidine lead to full derivative dissolution of cellulose in DMSO, on which, the reactive behavior of celllulose with L-Lactide was investigated. The reaction conditions was optimized and the structure and properties of the as-prepared cellulose-graft-poly-(L-lactide) copolymer were investigated by using variou characteristic technologies, such as NMR, FT-IR and TG.In conclusion, with the newly developed dissolution and activation technology for cellulose by using CO2, serials of cellulose esters can be synthesized with high efficiency, which provided greener and new strategies for cellulose derivatives preparation.