Dynamics of hollow nanofiber formation during solidification subjected to solvent evaporation

To mimic the emergence of gradient morphology in polymer nanofibers, a new theoretical approach has been developed in the context of Cahn-Hilliard time evolution equation, alternatively known as time-dependent Ginzburg-Landau equation (Model B) involving concentration order parameter. The effects of solvent evaporation on the morphology evolution of the nanofibers have been demonstrated. The numerical simulation showed that the formation of skin layers is governed by the competition between solvent evaporation rate and mutual diffusion rate. That is to say the skin layers are formed in the nanotube whenever the rate of evaporation exceeds a critical value; otherwise, a solid fiber is formed. In hollow nanofibers, the layer can grow to a substantial fraction of the fiber diameter, allowing it to remain intact, albeit often in a collapsed form.