Protein purification with polymeric affinity membranes containing functionalized poly(acid) brushes.

Porous nylon membranes modified with poly(acid) brushes and their derivatives can rapidly purify proteins via ion-exchange and metal-ion affinity interactions. Membranes containing poly(2-(methacryloyloxy)ethyl succinate) (poly(MES)) brushes bind 118 +/- 8 mg of lysozyme per cm(3) of membrane and facilitate purification of lysozyme from chicken egg white. Moreover, functionalization of the poly(MES) brushes with nitrilotriacetate (NTA)-Ni(2+) complexes yields membranes that bind poly(histidine)-tagged (His-tagged) ubiquitin with a capacity of 85 +/- 2 mg of protein per cm(3) of membrane.

Highly ordered palladium nanodots and nanowires from switchable block copolymer thin films.

We demonstrate a new approach to fabricate highly ordered arrays of nanoscopic palladium dots and wires using switchable block copolymer thin films. The surface-reconstructed block copolymer templates were directly deposited with palladium nanoparticles from a simple aqueous solution. The preferential interaction of the nanoparticles with one of the blocks is mainly responsible for the lateral arrangement of the nanoparticles inside the pores of the templates in addition to the capillary forces.

Nanowear studies in reversibly switchable polystyrene-poly(acrylic acid) mixed brushes.

Wear studies were performed on polystyrene (PS)-poly(acrylic acid) (PAA) mixed polymer brushes and corresponding monobrushes in a dried state. The aim was to study the wear mechanism in polymer brush surfaces as well as to investigate the effect of switching of PS + PAA binary brush surfaces (on treatment with the selective solvents for the PS and PAA) on the wear process. Wear experiments were carried out using atomic force microscopy (AFM) under a controlled environment.

Switching of friction by binary polymer brushes.

Surface force studies on polystyrene-poly(2-vinylpyridine) (1 : 1) mixed polymer brushes and corresponding monobrushes were carried out in dried state under a controlled environment. The aim was to explore possibilities to control adhesion and friction between inorganic or polymeric surfaces by use of polymer brushes. The effect of switching of chemical composition of binary brush surfaces (on treatment with suitable solvents) on wettability, surface roughness, and hence the adhesion and friction properties of the surfaces were determined.