Continuous Production of Macroporous Films: an Alternative to Breath Figure Assembly

Despite the need for sophisticated instrumentation, breath figure assembly (BFA) methods are restricted to produce macroporous films on a tiny scale so far. The current study narrates the fabrication of macroporous films in hollow fiber geometry which extends to adopt the method for continuous production of isoporous surfaces from commercially available low-priced polymer materials. The fabrication of the films in the hollow fiber geometry is carried out by a co-centric quadruple orifice spinneret through which four different liquids are co-extruded simultaneously: bore fluid (to fill the lumen of the fiber), support layer solution, glycerol, and an isoporous film forming solution through the outer most orifice. The extruded entities plunge into a coagulation bath after passing a definite air gap. The implementation of the concept of diffuse-in, droplet formation, and then condense-out behavior of glycerol in a co-extrusion method of hollow fiber spinning makes macroporous film formation possible in an interminable way sidestepping the use of breath figure assembly method. Moreover, the continuous film formation by the proposed mechanism is also authenticated in flat sheet geometry by employing two casting blades in a casting machine. The structure of the films is analyzed by scanning electron microscopy (SEM).