Reinforced superhydrophobic membrane coated with aerogel-assisted polymeric microspheres for membrane distillation

Polymeric microsphere coating through electrospraying utilizing a polymer mixture of polyvinylidene fluoride (PVDF) and poly(dimethylsiloxane) (PDMS) is a facile method for fabricating a superhydrophobic surface. This study describes another simple approach for improving polymeric microsphere coating by adding hydrophobic aerogel particles to the polymeric solution for electrospraying. The deformation of microspheres, such as the occurrence of broken microspheres and polymeric strings, became apparent as the concentration of aerogel particles was increased. Consequently, while the pure microsphere-coated membrane showed a 156.7° contact angle, that of the 30% aerogel-assisted microsphere-coated membrane was 162.1° with a water droplet easily rolling on it. In addition, the 30% aerogel-assisted microsphere-coated membrane exhibited a high and stable repellency during continuous contact with a relatively low surface tension solution of 3.5% NaCl containing 0.1 mM sodium dodecyl sulfate (SDS). As a result, the coated membrane demonstrated highly stable vapor permeability according to direct contact membrane distillation (DCMD) testing using 3.5% NaCl solution including 0.1 mM SDS.