title: Dispersibility and emulsion-stabilizing effect of cellulose nanowhiskers esterified by vinyl acetate and vinyl cinnamate.
abstract: The surface of cotton cellulose nanowhiskers (CNW's) was esterified by vinyl acetate (VAc) and vinyl cinnamate (VCin), in the presence of potassium carbonate as catalyst. Reactions were performed under microwave activation and monitored by Fourier transform infrared (FT-IR) spectroscopy. The supramolecular structure of CNW's before and after modification was characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). Distinctively from the acetylation treatment, an increase in particles dimensions was noted after esterification with VCin, which was assigned to π-π stacking interactions that may exist between cinnamoyl moieties. The dispersibility and emulsion stabilizing effect of acylated CNW's was examined in ethyl acetate, toluene, and cyclohexane, three organic solvents of medium to low polarity. The acylated nanoparticles could never be dispersed in toluene nor cyclohexane, but they formed stable dispersions in ethyl acetate while remaining dispersible in water. Stable ethyl acetate-in-water, toluene-in-water, and cyclohexane-in-water emulsions were successfully prepared with CNW's grafted with acetyl moieties, whereas the VCin-treated particles could stabilize only the cyclohexane-in-water emulsions. The impact of esterification treatment on emulsion stability and droplets size was particularly discussed.
authors.affiliation: Université Bordeaux, LCPO, UMR, Pessac, France. gilles.sebe@u-bordeaux1.fr
authors.forename: Gilles
authors.initials: G
authors.lastname: Sèbe
authors.forename: Frédérique
authors.initials: F
authors.lastname: Ham-Pichavant
authors.forename: Gilles
authors.initials: G
authors.lastname: Pecastaings
mesh_terms: D000085:Acetates / Q000737:chemistry; D002482:Cellulose / Q000737:chemistry*; D002934:Cinnamates / Q000737:chemistry*; D003510:Cyclohexanes / Q000737:chemistry; D045703:Emulsifying Agents / Q000138:chemical synthesis* / Q000737:chemistry; D004655:Emulsions; D004951:Esterification; D018625:Microscopy, Atomic Force; D057139:Nanofibers / Q000737:chemistry* / Q000648:ultrastructure; D012997:Solvents / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013500:Surface Tension; D014050:Toluene / Q000737:chemistry; D014753:Vinyl Compounds / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D000085:Acetates; D002934:Cinnamates; D003510:Cyclohexanes; D045703:Emulsifying Agents; D004655:Emulsions; D012997:Solvents; D014753:Vinyl Compounds; D014867:Water; D014050:Toluene; C506365:Cyclohexane; C007650:ethyl acetate; D002482:Cellulose; C011566:vinyl acetate