Modification of membrane surfaces by grafting polymer brushes from the surface has been shown to impart unique surface properties. These polymer brushes can be used as ligands in membrane adsorbers, they can be used to reduce membrane fouling as well as for the development of responsive membranes that can change their conformation in response to an external stimulus1,2. Here we focus on magnetically responsive membranes where magnetically responsive polymer chains are grown from the membrane surface. We have developed a range of microfiltration3, ultrafiltration and nanofiltration4,5 membranes by grafting magnetically responsive polymer brushes from the membrane surface. Atom transfer radical polymerization (ATRP) has been used to graft poly-hydroxyethyl methacrylate (polyHEMA) from the surface of the membrane. Superparamagnetic nanoparticles have been attached to the chain ends. In an oscillating magnetic field, movement of the magnetically responsive nanobrushes leads to suppression of concentration polarization resulting in higher permeate fluxes and better rejection. We have also grafted poly(N-isopropylacrylamide) a thermo-responsive polymer that exhibits a lower critical solution temperature, using ATRP, from the surface of the membrane. By carefully choosing the frequency of the oscillating magnetic field, movement of the polymer chains can induce mixing. Using much higher frequencies, around 1,000 Hz, heating will lead to collapse of poly(N-isopropylacrylamide) layer as the temperature of the grafted polymer layer increase above the lower critical solution temperature of the grafted poly(N-isopropylacrylamide).

Selective modification of membrane pore and external surfaces

255th National Meeting (2018)

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