Modeling of composite fiber production with silica nanoparticles dispersed in polyethyleneoxide R. Furlan a, * , E.W. Sim~ oes b , M.L.P. da Silva b,c , I. Ramos a , E. Fachini d a University of Puerto Rico at Humacao, Physics and Electronics Department, CUH Station, 100, 908 Road, Humacao, Puerto Rico 00791, USA b Polytechnic School, University of S~ ao Paulo, Av. Luciano Gualberto 158, Trav.3, S~ ao Paulo, SP 05508900, Brazil c Faculty of Technology of S~ ao Paulo, Pc ¸a Cel. Fernando Prestes, 30, S~ ao Paulo, SP 01124060, Brazil d University of Puerto Rico at Rı ´o Piedras, Facundo Bueso Bldg., FB-B1, San Juan, Puerto Rico 00931, USA Received 5 February 2007; received in revised form 15 June 2007; accepted 18 June 2007 Available online 23 June 2007 Abstract In this work silica nanoparticles were incorporated in a polymeric matrix (fibers) aiming at the production of new composite materials that can be useful for the development of nanomaterials and/or microanalysis systems. Polyethyleneoxide and Ludox TM-50 were used as phases for elec- trospinning. Due to the high amount of effective charge present in the solutions, a new setup for electrospinning was devised by adding another electrode to a conventional deposition system. The presence of this electrode was investigated numerically using electrostatic application mode of the COMSOL Multiphysics 3.2b package. The simple model developed to explain the nanoparticle behavior for the used electrospinning setup showed good agreement with the experimental results and can be useful for simulations in the production of similar composites. Fibers with a high amount of particles were obtained using this third electrode biasing the flow in a preferred direction. Infrared spectra, EDX and SEM microscopy analysis show nanoparticle incorporation in the fibers. Ó 2007 Elsevier Ltd. All rights reserved. Keywords: Composite; Nanoparticles; Fiber formation 1. Introduction Invented in the 1930s, electrostatic deposition (or electro- spinning) technique has recently gained significant interest because it can produce a variety of ultra fine polymer fibers in the micro or even nano-scale diameters at low cost [1e5]. Huang et al. [1] compared in detail this technique with others used to obtain polymeric fibers and, also, gave extensive infor- mation about the use of different types of polymers with elec- trospinning. Recent works have demonstrated the feasibility of obtaining alignment of fibers and structures (normally pads for electric contact) previously defined on the substrate [6,7]. A typical electrospinning process is depicted in Fig. 1 [1]. An electrostatic field is used to form and accelerate liquid jets from the tip of a capillary. The surface of a hemispherical liq- uid drop suspended in equilibrium at the end of the capillary will be distorted into a conical shape in the presence of the electric field. The balancing of the repulsive force, resulting from the induced charge distribution on the surface of the drop with the surface tension of the liquid, causes this distor- tion. Once a critical voltage is exceeded, a stable jet of liquid is ejected from the cone tip. For a sufficiently viscous liquid the jet travels to the grounded target and the solvent evapo- rates. Charged polymer fibers are formed and lay themselves randomly on the collecting metallic electrode. It is well known that the morphology of the resulting fibers is determined by a synergetic effect of solution parameters and electrostatic forces [8e12]. These parameters include viscos- ity, surface tension, concentration and dielectric properties of the spinning solution and process parameters such as the feed rate of the solution to the tip and acceleration voltage. Controlling the process parameters, the fibers can be * Corresponding author. Tel.: þ1 787 8509381; fax: þ1 787 8509308. E-mail address: rfurlan@mate.uprh.edu (R. Furlan). 0032-3861/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.polymer.2007.06.041 Polymer 48 (2007) 5107e5115 www.elsevier.com/locate/polymer