Fabrication of open-cell porous fibers by templating from high internal phase emulsions (HIPEs) provides an environmentally friendly processing alternative to electrospinning. Such fibers have many potential applications, including, for example, encapsulation and controlled release systems, or woven or non-woven absorbent materials. In this work, we investigate the possibility of tuning the surface morphology of the fibers by altering the chemistry of the bath in which the fibers are cured.
Two different synthesis routes were investigated. In one, the bath conditions included variations on the chemistry (e.g., concentrations of electrolyte and initiator) used for the poly(HIPE) itself. For example, the presence of salt or initiator in the curing bath results in fibers with relatively low porosity surfaces, while having both salt and initiator present results in a porous surface. In the second synthesis approach, interfacial polymerization was performed to grow a shell of a second material around the poly(HIPE) fiber.
The structure of the various types of fibers was investigated through the use of scanning electron microscopy, TGA tests to measure water evaporation rates from the fibers, and observation of dye absorption kinetics. The effects of bath conditions on the fiber morphology are interpreted on the basis of physicochemical effects that occur at the fiber-bath interface. Results show that it is possible to fabricate fibers in which the surface porosity ranges for fairly open to completely closed.