resumo
The surface hydrophobization through heterogeneous chemical modification of bacterial (and vegetable) cellulose fibers with several anhydrides (acetic, butyric, hexanoic and alkenyl succinic anhydrides) and hexanoyl chloride suspended in an ionic liquid, tetradecyltrihexylphosphonium bis(trifluoromethylsulfonyl) imide, [TDTHP][NTf2], was studied. Furthermore, in the reaction with hexanoyl chloride, another ionic liquid, N-hexyl-4-(dimethylamino)pyridinium bis(trifluoromethylsulfonyl) imide, [C6N(CH3)(2)py][NTf2], was used instead of common organic bases as catalyst and to trap the released HCl. The analysis of the ensuing modified fibers by FTIR, XRD and SEM clearly showed that the esterification reactions occurred essentially at the fibers' outmost layers, not affecting their ultrastructure. The degree of substitution (DS) of the ensuing esterified fibers ranged from less than 0.002 to 0.41; and in all instances, the fibers' surface acquired a high hydrophobicity. This novel approach constitutes an important strategy in the preparation of modified fibers under greener conditions relaying in the use of non-volatile solvents.
palavras-chave
NANOFIBRILLATED CELLULOSE; BARRIER PROPERTIES; FATTY-ACIDS; ACETYLATION; MEMBRANES; BEHAVIOR; WATER
categoria
Chemistry; Science & Technology - Other Topics
autores
Tome, LC; Freire, MG; Rebelo, LPN; Silvestre, AJD; Neto, CP; Marrucho, IM; Freire, CSR
nossos autores
Armando Jorge Domingues Silvestre
Professor Catedrático
Carlos Pascoal Neto
Diretor do Raiz
Carmen Sofia da Rocha Freire Barros
Investigador Coordenador
Isabel Maria Delgado Jana Marrucho Ferreira
Professor Catedrático
Liliana C. Tomé
Estudante de doutoramento
Mara Guadalupe Freire Martins
Investigador CoordenadorGrupos
G4 - Materiais Renováveis e Economia Circular
G5 - Materiais Biomiméticos, Biológicos e Vivos
Projectos
agradecimentos
FCT (Fundacao para a Ciencia e Tecnologia) is acknowledged for Liliana C. Tome (PhD research grant SFRH/BD/72830/2010) and Mara G. Freire (Postdoctoral research grant SFRH/BPD/41781/2007), and for financial support through the Projects PTDC/QUI/68472/2006 and PTDC/QUI/72903/2006. The authors also acknowledge Cytec Industries for kindly providing [TDTHP][NTf