Fouling Resistance and Release Properties of Poly(sulfobetaine) Brushes with Varying Alkyl Chain Spacer Lengths and Molecular Weights.

We examined the effects of alkyl carbon spacer length (CSL) and molecular weight on fouling resistance and release properties of zwitterionic poly(sulfobetaine methacrylate) brushes. Using surface-initiated atom transfer radical polymerization, we synthesized two series of brushes with CSL = 3 and 4 and molecular weight from 19 to 1500 kg ·mol, corresponding to dry brush thickness from around 6 to 180 nm. The brush with CSL = 3 was nearly completely wet with water (independent of molecular weight), whereas the brush with CSL = 4 exhibited a strong increase in water contact angle with molecular weight.

Effect of Dispersity on the Conformation of Spherical Polymer Brushes.

We show that dispersity () markedly alters the conformation of spherical polymer brushes. The average lengths () of poly(-butyl acrylate) (PBA) brushes of varying grafted to nanoparticles were measured using dynamic light scattering. In the semidilute polymer brush (SDPB) regime, the of PBA and polymers from earlier studies of various could be cleanly collapsed onto a master curve as a function of the scaling variable σ, where is the weight-average degree of polymerization and σ is the grafting density.

Tuning Bacterial Attachment and Detachment via the Thickness and Dispersity of a pH-Responsive Polymer Brush.

We investigated the effect of two brush parameters, thickness and dispersity in the molecular weight distribution, on the adhesion of bacteria to pH-responsive poly(acrylic acid) (PAA) brushes synthesized using surface-initiated atom transfer radical polymerization. The attachment and detachment of Staphylococcus epidermidis to PAA brushes at pH 4 and pH 9, respectively, were examined with confocal microscopy. An optimal range of brush thickness, 13-18 nm, was identified for minimizing bacterial adhesion on PAA brushes at pH 4, and bacterial attachment did not depend on the brush dispersity.