title: Surface esterification of cellulose nanofibers by a simple organocatalytic methodology.
abstract: Bacterial cellulose nanofibers were esterified with two short carboxylic acids by means of a simple and novel organic acid-catalyzed route. The methodology proposed relayed on the use of a non-toxic biobased α-hydroxycarboxylic acid as catalyst, and proceeded under moderate reaction conditions in solventless medium. By varying the esterification interval, acetylated and propionized bacterial cellulose nanofibers with degree of substitution (DS) in the 0.02-0.45 range could be obtained. Esterified bacterial cellulose samples were characterized by means of Solid-State CP/MAS (13)C Nuclear Magnetic Resonance spectroscopy (CP/MAS (13)C NMR), Fourier Transform Infrared spectroscopy (FTIR), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA) and chosen hydrophobicity test assays. TGA results showed that the esterified nanofibers had increased thermal stability, whereas XRD data evidenced that the organocatalytic esterification protocol did not alter their crystallinity. The analysis of the ensuing modified nanofibers by NMR, FTIR, XRD and TGA demonstrated that esterification occurred essentially at the surface of bacterial cellulose microfibrils, something highly desirable for changing their surface hydrophilicity while not affecting their ultrastructure.
authors.affiliation: Grupo de Biotecnología y Biosíntesis-Instituto de Tecnología en Polímeros y Nanotecnología (ITPN)-Facultad de Ingeniería, Universidad de Buenos Aires, Las Heras 2214 (CP 1127AAR), Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina.
authors.forename: Jhon Alejandro
authors.initials: JA
authors.lastname: Ávila Ramírez
authors.affiliation: Grupo de Biotecnología y Biosíntesis-Instituto de Tecnología en Polímeros y Nanotecnología (ITPN)-Facultad de Ingeniería, Universidad de Buenos Aires, Las Heras 2214 (CP 1127AAR), Buenos Aires, Argentina.
authors.forename: Camila Juan
authors.initials: CJ
authors.lastname: Suriano
authors.affiliation: Grupo de Biotecnología y Biosíntesis-Instituto de Tecnología en Polímeros y Nanotecnología (ITPN)-Facultad de Ingeniería, Universidad de Buenos Aires, Las Heras 2214 (CP 1127AAR), Buenos Aires, Argentina; Departamento de Ingeniería Química, Facultad de Ingeniería, Universidad de Buenos Aires, Argentina.
authors.forename: Patricia
authors.initials: P
authors.lastname: Cerrutti
authors.affiliation: Grupo de Biotecnología y Biosíntesis-Instituto de Tecnología en Polímeros y Nanotecnología (ITPN)-Facultad de Ingeniería, Universidad de Buenos Aires, Las Heras 2214 (CP 1127AAR), Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina. Electronic address: mforesti@fi.uba.ar.
authors.forename: María Laura
authors.initials: ML
authors.lastname: Foresti
mesh_terms: D002384:Catalysis; D002482:Cellulose / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D057139:Nanofibers / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D014961:X-Ray Diffraction
chemical_list: D002482:Cellulose
keywords: Bacterial cellulose; Characterization; Organocatalysis; Surface esterification