Nanofibers of n-Butyl Acrylate/Methyl Methacrylate copolymer [P(BA-co-MMA)] were produced by electrospinning in this study. P(BA-co-MMA) was synthesized by emulsion polymerization. The structural and thermal properties of copolymers and electrospun P(BA-co-MMA) nanofibers were analyzed using Fourier transform infrared spectroscopy-Attenuated total reflectance (FTIR-ATR), Nuclear magnetic spectroscopy (NMR), and Differential scanning calorimetry (DSC). FTIR-ATR spectra and NMR spectrum revealed that BA and MMA had effectively participated in polymerization. The morphology of the resulting nanofibers was investigated by scanning electron microscopy, indicating that the diameters of P(BA-co-MMA) nanofibers were strongly dependent on the polymer solution dielectric constant, and concentration of solution and flow rate. Homogeneous electrospun P(BA-co-MMA) fibers as small as 390 +/- 30 nm were successfully produced. The dielectric properties of polymer solution strongly affected the diameter and morphology of electrospun polymer fibers. The bending instability of the electrospinning jet increased with higher dielectric constant. The charges inside the polymer jet tended to repel each other so as to stretch and reduce the diameter of the polymer fibers by the presence of high dielectric environment of the solvent. The extent to which the choice of solvent affects the nanofiber characteristics were well illustrated in the electrospinning of [P(BA-co-MMA)] from solvents and mixed solvents. Nanofiber mats showed relatively high hydrophobicity with intrinsic water contact angle up to 120 degrees. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4264-4272, 2013