(524b) Kidney-Inspired Membranes with Enhanced Anti-Fouling Properties, through Grafting of Stimuli-Responsive Polymer Brushes

Fouling represents one of the biggest bottlenecks in membrane technology. To tackle this problem, we seek inspiration in the kidney, a remarkable organ capable of producing over four million litres of effectively protein-free urine over a lifetime with no significant fouling (1). The glomerulus is a bundle of specialized blood vessels, which carries out the first stage of kidney filtration, the stage most comparable to membrane separations. Within the lumen of these blood vessels, a brush-like structure is present, composed of proteoglycans and glycoproteins, which are responsible for the overall negative charge and hydrophilicity of this layer. The combination of the brush structure, hydrophilicity and charge of the system are believed to be key causes behind the superior anti-fouling properties of the kidney.

To translate this source of inspiration into the context of artificial membranes, the design employed here involves the grafting of polyelectrolyte polymer brushes as an anti-fouling layer onto track-etched polyester (PET) membranes. This grafting is achieved through Surface-Initiated Controlled Radical Polymerization (SI-CRP) using Activators Regenerated by Electron Transfer Atomic Transfer Radical Polymerization (ARGET ATRP). The stimuli-responsive polymer brushes reduce fouling through the formation of a hydration layer, steric repulsion and electrostatic interactions, due to the negative charge of the layer at pH above its pKa. This has been demonstrated in the filtration of bovine serum albumin. The flux decline for the modified membranes showed a significant improvement over unmodified membranes with maximum flux declines of 24% and 60% over 0.5 h, respectively. This is related to the enhanced hydrophilicity of the membranes seen in Figure 1.

1. Hausmann R et al., The glomerular filtration barrier function: new concepts, Curr. Opin. Nephrol. , 2012, 21(4), 441–9.