Electrospun nanofiber membranes from polyampholyte/ poly(vinylidene fluoride) blends

Polyampholytes are amphoteric macromolecules containing randomly mixed oppositely charged groups. Due to the positively and negatively charged moieties on different monomers, polyampholytes show excellent anti-fouling properties and are used extensively in filtration applications. In this study, we electrospun nanofibrous membranes from a random polyampholyte amphiphilic copolymer (r-PAC) blended with poly(vinylidene fluoride) (PVDF) a commercially available semi-crystalline polymer that shows excellent hydrophobic properties. The r-PACs are composed of monomers that are either hydrophobic (2,2,2-trifluoroethyl methacrylate); positively charged ([2-(methacryloyloxy) ethyl]trimethylammonium chloride); or negatively charged (methacrylic acid). In the electrospun membranes, fouling resistance is provided by hydrophilic units of r-PAC and mechanical and chemical stability is provided by PVDF and hydrophobic units in r-PAC. The blend composition was varied by controlling the ratio of PVDF to r-PAC. The electrospun fiber mats were characterized for their structure using wide-angle X-ray scattering, Fourier-transform infrared spectroscopy, and Raman spectroscopy. Degradation temperature and glass transition properties were evaluated using thermogravimetric analysis and differential scanning calorimetry, respectively. Hydrophilicity was evaluated using sessile drop contact angle measurements.