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

Abstract

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).

Growth dynamics of surface nanodroplets during solvent exchange at varying flow rates

“…The normalized volume shows a sharp increase before approaching the plateau near the final droplet volume. The experimental data are well fitted by the error function result eqn (6), particularly at the lower flow rates. However, there was some noise in the measurements which could not be avoided.…”

“…Droplet formation on surfaces is paramount to a growing number of fundamental and applied processes. [1][2][3][4] Areas of interest include breath figure templating 5,6 and the condensation of droplets on liquid repellent surfaces. 7,8 Surface droplets are also relevant for high throughput screening 9 and compartmentalized biological conversion in microdroplet arrays.…”

Hollow Fiber Membranes of Blends of Polyethersulfone and Sulfonated Polymers

“…The hollow fibers were spun by the dry-jet wet spinning method where the dope solution was extruded through the spinneret together with the bore fluid [ 21 ]. The spun fibers entered into the coagulation bath (water) after experiencing a definite air gap distance (L Air ) where the solid hollow fibers formed by non-solvent induced phase separation (NIPS).…”

Defect-free outer-selective hollow fiber thin-film composite membranes for forward osmosis applications

“…These parameters were then adjusted to alter the dimension and morphology of the membrane substrates. In this study, the air-gap distance was carefully manipulated in the range of 2-8 cm to modify the outer surface morphology of the membrane substrates [32,33]. Figure 1 depicts the schematic diagram for OSHF membrane substrates preparation as a function of the airgap distance.…”