Design of hydrophobic polymer brush for mitigation of membrane wetting in membrane distillation- computer simulation

Abstract

Defined as an assembly of polymer chains which are tethered by one end to a surface or an interface, polymer brushes have found many applications. In particular, grafting of hydrophilic polymer brushes to the membrane surface was used to mitigate fouling of filtration membranes. As well, hydrophobic polymer brushes were grafted on top of a solid substrate to be used for organic selective pervaporation. In this work, grafting of hydrophobic brushes to the surface of membranes for membrane distillation (MD) is proposed to prevent MD membranes from wetting. This is not an experimental work but a computer simulation of designing the polymer brush or patterned polymer brush to optimize their effect on wetting prevention. It was found that such an effect increases with an increase in the distance between brushes, the contact angle and the radius of the cylindrical polymer brush. Considering the decrease in the effective area of the membrane used for vapor permeation by grafting of polymer brush, the optimal distance between the brushes was found to be twice as large as the brush diameter for millimeter-sized brush and three times as large as the brush diameter of micro- or nanometer sized brushes.