Preparation and characterization polyvinylidene fluoride membranes from water and ethanol coagulants via in situ free radical polymerization

Abstract

In this present study, the facile approaches of coagulants and in situ free radical polymerization method for modulating configurations and performances of polyvinylidene fluoride (PVDF) membranes are investigated. Configuration images show that the supramolecular aggregates of PVDF‐P(PEGMA‐r‐MMA) caused by in situ polymerization act as “template” of the tuned configurations of the resultant PVDF membranes. During delay demixing process (ethanol coagulant), the confine of the aggregates resulted in shift of the cauliflower nanograins to the stripe‐type nanograins. On the other hand, for the membranes prepared from the instantaneous demixing process in water coagulant, the aggregates contributed to the formation of the confined finger‐like structures and the globule agglomerates that constructed the whole thickness of the membrane bulk. Furthermore, those narrow distribution supramolecular aggregates and variation coagulants (water and ethanol) also yield the tuned performances. The membranes' improved mechanical properties and limited hydrophilicity improvement are attributed to the strong interconnection between the aggregates. Because of the fore‐forming of the P(PEGMA‐r‐MMA) aggregates with narrow distribution, all PVDF membranes prepared from the two coagulants possess enlarged flux, narrow distribution mean effective pore size (μ), and molecular weight cut‐off. The delay demixing process contributes to the narrower μ and molecular weight cut‐off, as well increased flux. Copyright © 2014 John Wiley & Sons, Ltd.