Preliminary analysis of a linear pore pattern formed on poly(vinylidene fluoride-co-hexafluoro propylene) porous membrane surfaces

In addition, a clearer image of the linear pore pattern was captured when lower concentration polymer dopes were used. In contrast, this phenomenon was invisible for the membrane formed by a higher concentration dope, which is in agreement with the reduction of orientation degree with increasing polymer concentration. Moreover, the systems containing additives with lower viscosity, such as glycerol, glycol, diethylene glycol and glucose, seem to be easier to form a linear pore pattern than the one containing distilled water, the latter produced a nearly elliptical pore pattern on the membrane surface instead. The investigation on this feature may provide more information for a complete description of the initiation and growth of the porous membrane.