Theoretical selection of solvent for production of electrospun PMMA fibers with wrinkled surfaces
A Bagley graph is a 2D solubility chart that contains the Hansen solubility parameters of polymers and solvents to provide a systematic and theoretical method for selecting solvents during electrospinning. The interaction radius of the solubility circle of poly methyl methacrylate (PMMA) is 8.59 MPa0.5. In the Bagley graph of PMMA, ethanol is located outside of the solubility circle and is therefore a non-solvent for PMMA. In the current study, ethyl acetate (EA) was chosen as the solvent for electrospinning PMMA to investigate the effects of variations in the applied voltage and solution concentration on spinnability and fiber morphologies. Statistical analysis showed that varying the applied voltage (14–20 kV) and solution concentration (6–8%) does not produce a significant difference in average fiber diameter. The surface of the PMMA fiber was irregularly wrinkled due to spinodal decomposition from thermal induced phase separation. Software developed with the Delphi 7.0 programming language was used to predict the liquid–liquid phase separation of mixing systems. Conclusively, the wrinkling was caused by the thermodynamic instability of the polymer solution undergoing rapid volatilization of EA.