Effect of solvents on the morphology of electrospun atactic polystyrene

Samples of atactic polystyrene (a-PS) were dissolved in tetrahydrofuran, N, N-dimethylfonnamide and chloroform with tetrahydrofuran and N, N-dimethylformamide as co-solvents and electrospun to dentify precisely the effect of solvent properties like viscosity and boiling point on the morphologies of the electrospun polymers. The forms of bead, bead-onto-fibre, and fibre were prepared and their stable formation conditions were established through a series of electrospinning experiments under various processing conditions. At low concentrations of the a-PS solution in tetrahydrofuran and chloroform, half hollow spheres and collapsed spheres were obtained whereas "apple" type spheres, resembling apples, were obtained in N, N-dimethylformamide. In contrast, web composed of uniform microfibers were prepared at higher concentrations. These results were attributed mostly to differences in evaporation rates and in the viscosities of the solvent and the solutions. In conclusion it is possible to obtain a-PS webs having various fine morphologies by controlling the processing parameters during electrospinning.