ORIGINAL PAPER All-Cellulose Composite Fibers Obtained by Electrospinning Dispersions of Cellulose Acetate and Cellulose Nanocrystals Marı ´a E. Vallejos • Maria S. Peresin • Orlando J. Rojas Ó Springer Science+Business Media, LLC 2012 Abstract All-cellulose composite fibers were produced by electrospinning dispersions containing cellulose acetate (CA) and cellulose nanocrystals (CNCs). Precursor poly- mer matrices were obtained after dispersion of CA with different degrees of substitution in a binary mixture of organic solvents. The obtained fibers of CA loaded with CNCs had typical widths in the nano- and micro-scale and presented a glass transition temperature of 145 °C. The CA component was converted to cellulose by using alkaline hydrolysis to yield all-cellulose composite fibers that pre- served the original morphology of the precursor system. Together with Fourier Transform Infrared Spectroscopy fingerprints the thermal behavior of the all-cellulose com- posite fibers indicated complete conversion of cellulose acetate to regenerated cellulose. Noticeable changes in the thermal, surface and chemical properties were observed upon deacetylation. Not only the thermal transitions of cellulose acetate disappeared but the initial water contact angle of the web was reduced drastically. Overall, we propose a simple method to produce all-cellulose com- posite fibers which are expected to display improved thermo-mechanical properties while keeping the unique features of the cellulose polymer. Keywords Cellulose acetate  Cellulose  All-cellulose composite  Nanofibers  Cellulose nanocrystals  Deacetylation  Electrospinning Introduction Materials in the form of nano- and micro-fibers present unique properties when compared to other morphologies mainly due to the high surface area-to-weight ratio, high pore volume, and small pore size [1]. Processing of poly- mers to obtain nanofibers can be carried out by using methods such as drawing, template assisted synthesis, phase separation, self-assembly, and electrospinning [2–4]. Among these techniques, electrospinning is a versatile technique in terms of its simplicity and relative low-cost. The diameter and morphology of fibers obtained by elec- trospinning (ES) depend on the process conditions and variables such as polymer concentration and viscosity, net charge density of the solution, applied voltage, distance to the collector, and the type of collector. Furthermore, free electrospun webs present random fiber distribution on the collector, which generate a high surface roughness. Usu- ally, solvent mixtures are used to control solvent evapo- ration during the electrospinning process, and thus avoid clogging of the spinneret by early solidification of the polymer [5–8]. Fibers produced by electrospinning have shown potential for applications in medicine (tissue engi- neering, wound dressing, drug delivery and dental and medical implants) [3, 9], high performance air filters, M. E. Vallejos Programa de Investigacio ´n de Celulosa y Papel, Facultad de Ciencias Exactas, Quı ´micas y Naturales, Universidad Nacional de Misiones, Fe ´lix de Azara 1552, 3300 Posadas, Misiones, Argentina M. S. Peresin VTT—Technical Research Centre of Finland, Biologinkuja 7, P.O. Box 1000, 02044 Espoo, Finland O. J. Rojas (&) Department of Forest Biomaterials, North Carolina State University, campus box 8005, Raleigh, NC 27695-8204, USA e-mail: orlando_rojas@ncsu.edu O. J. Rojas Department of Forest Products Technology, School of Chemical Technology, Aalto University, 00076 Aalto, Espoo, Finland 123 J Polym Environ DOI 10.1007/s10924-012-0499-1