Synthesis Of Cellulose Esters In DBU/DMSO/CO₂ And Their Properties Study

The economy of depleting petroleum resources coupled with increasing environmental have ignited the interest in the use of renewable cellulosic polymers from different resources for making new materials.Cellulose esters constitute a family of well-known commercialproducts.Cellulose grafted polycaprolactone have a great potential of application as drug carriers and nanotechnology. Cellulose was the most abundant renewable nature biomass material, It is a promising ―green‖ material owing to its unique properties such as nontoxicity, recyclability,have good mechanical properties and low cost.This paper based on the1,8-Diazabicyclo[5.4.0]undec-7-ene(DBU)/DMSO/CO2 system dissolving microcrystalline cellulose and cotton cellulose synthesis of cellulose acetate propionate and cellulose acetate butyrate and cellulose derivatives grafted polycaprolactone. The experimental results were as follows:1. In this study, mixed cellulose esters were homogeneous prepared in DBU/DMSO/CO2 system. Various parameters of acylation, such as reaction time, temperature, and the molar ratio of the anhydride/AGU in cellulose were investigated. The result show that cellulose acetate propionate with a DS of 2.85 was achived after two hours at 80℃,a molar ratio of anhydride/ AGU at 5:1. The structures and thermal properties of the obtained mixed cellulose esters were characterized by means of NMR, Fourier transform infrared(FT-IR) and thermogravimetric analysis(TGA). The DSC results revealed that the Tg increases with the decrease of DS, may be the higher the degree of substitution, the weaker hydrogen bonds.2. In this study, novel biodegradable amphiphilic cellulose derivatives were prepared by grafting PCL onto underivatized cellulose via homogeneous ROP in DBU/DMSO/CO2 system.The DBU not only acted as an important reagent for the derivative dissolution of cellulose, but also acted as an organic catalyst for the subsequent ROP process.The molecular architecture of the copolymers was controlled by reaction temperature, reaction time, cellulose: ε-CL feed ratio, etc. cellulose-g-PCL copolymers with a substitution with a DS of 2.63 was achived after Twenty-four hours at 120℃,a molar ratio of ε-CL/AGU at 15:1.cellulose-g-PCL copolymers with a substitution of PCL in the range of 0.86-2.82 were successfully synthesized in this new dissolution and activation system.The structures and thermal properties of the obtained Cellulose grafted polycaprolactone were characterized by means of NMR, FT-IR and TGA.3. In this study, novel biodegradable amphiphilic cellulose derivatives were prepared by grafting PLLA onto underivatized cellulose via homogeneous ROP in DBU/DMSO/CO2 system. The result show that no reaction occurred in the absence of DBU, while cellulose-g-PLLA(DSPLLA=0.94, MSPLLA=1.07, WPLLA=32.2%) was obtained when DBU was added. Cellulose Graft polylactic acid with a DS of 0.61 when Cellulose without carbon dioxide activating This may be cellulose hydroxy active low without activation.The DBU not only acted as an important reagent for the derivative dissolution of cellulose, but also acted as an organic catalyst for the subsequent ROP process.In conclusion, we developed a new method for homogeneous synthesis of cellulose mixed esters and Cellulose grafted polycaprolactone stimulated by the successful dissolution of cellulose in DBU/DMSO/CO2 system. The structures and properties of cellulose esters and Cellulose grafted polycaprolactone were studied. This process opened a new opportunities for preparation of cellulose derived materials.