Synthesis And Characterize Of Cellulose Acetate Acrylate Liquid Crystalline

Cellulose and many of cellulose derivatives can form liquid crystals under special conditions.The cellulose acetate acrylate(CAA) was prepared by homogeneous esterification of cellulose with acrylic acid which was accomplished with acetic anhydride co-reactant in lithium chloride/N,N-dimethylacetamide(LiCl/DMAc) medium.The investigation in this work involves:the synthesis of cellulose acetate acrylate,characterize cellulose acetate acrylate constructure,liquid crystalline properties,and the orientation of its UV-light solidified films.The influence of reaction temperature,reaction time,and acylation dosage as well as the percentage of activator to degree of substitution of the products were investigated. The chemical structures of products were characterized by FTIR.The crystallinity index was determined by X-ray diffraction.The thermal stabilities of cellulose and cellulose acetate acrylate were evaluated using thermogravimetric analysis(TGA).The thermal stability of cellulose acetate acrylate is lower than that of cellulose.Thermal properties of cellulose acetate acrylate was studied by differential scanning calorimetry(DSC),the curves showed the glass transition temperature of the cellulose acetate acrylate.From the theoretical calculation,we could got the value of solubility parameter(d) of CAA is 21.26.The liquid crystalline behavior of cellulose and cellulose acetate acrylate was studied by Polarized optical microscopy (POM).Neither the cellulose(2%wt) homogeneous solution nor the solution of cellulose acetate acrylate(2%wt)/DMAc can show liquid crystalline at room-temperature.However, they formed a liquid crystalline state when they were heated up to 100℃～110℃and the state can retain during the temperature falling.The optical texture shows that the liquid crystalline phases are probably sematic and cholesteric crystal,respectively.The critical concentration of liquid crystalline of cellulose acetate acrylate was 18%～25%.The photopolymerisation of the double bond of cellulose acetate acrylate in its oriented lyotropic solution "freezes" the orientation(which can be seen with a POM).The 2,2'-methoxy-2-phenylacetophenone was used as photosensitizer.It revealed that the optical properties of CAA could be preserved by photopolymerization.The chemical structures of films were characterized by FTIR.Crystallinity index of cellulose acetate acrylate films was determined by X-ray diffraction,it approved that the optical texture which had been seen with POM was liquid crystals but not spherulite.