Preparation Of A New UV-absorber Based On Natural Arabinoxylan

In this paper, Arabinoxylan(AX) was extracted from corn bran. It was used as a rawmaterial to prepare a novel polymer ultraviolet absorber Arabinoxylan cinnamic acidester(AXCM).AXCM was prepared expediently through a two-step synthesis route. Firstly, withpyridine as catalyst, AX was modified by bromine ethane in DMSO, then the alkylatedArabinoxylan(AAX) was obtained; Secondly, homogeneous esterification was conductedbeween AAX and cinnamoyl chloride(CM) in DMF, and the triethylamine was used as anacid-bonding agent. The chemical structures of AX, AAX and AXCM were confirmed byFT-IR,1H NMR,13C NMR and UV. It was found when reaction ratio of n(AX): n(C2H5Br)was8:1in the first step, the product AAX can dissolve and disperse in DMF. Whenn(AAX):n(CM) was4:1, the reaction temperature was60℃and reaction time was6h, thesubstitution degree (DS) of AXCM was high and the AXCM obtained can be dissolved inwater at the same time.The ultraviolet absorbing properties of AXCM were investigated. AXCM had strongultraviolet absorption from250nm to320nm with fine photostability. The UV damage on thecuticle can be reduced effectively when the AXCM was attached to the hair. In addition, thethermal stability of AXCM didn’t change a lot comparing with AX, and the thermaldegradation temperature of AXCM was245℃. As a polymer, the the entanglement ofmolecular chains increased the solution viscosity significantly. It was pseudoplastic fluid, forits viscosity increased with the decrease of shear rates.The solution behavior of AXCM was investigated by the methods of fluorescentmolecular probe, transmission electron microscope, and laser light scattering. The resultsdemonstrated that AXCM could aggregate as spherical in water through hydrophobicinteraction. The critical associating concentration(CAC) was about0.1mg/mL. The micellesizes was growing with the increase of DS of AXCM.Considering that the AX can be used as an emulsifier, emulsion properties of AXCMwere studied in this paper. The particle size and microspheres dispersion coefficient of AXCMwere small, and emulsifying ability of AXCM was superior than AX. When AXCM wasapplied in cosmetics emulsion system, its stability and compatibility were good.