P. S. Brown

Ultrafast Oleophobic–Hydrophilic Switching Surfaces for Antifogging, Self-Cleaning, and Oil–Water Separation

Smooth copolymer-fluorosurfactant complex film surfaces are found to exhibit fast oleophobic-hydrophilic switching behavior. Equilibration of the high oil contact angle (hexadecane = 80°) and low water contact angle (<10°) values occurs within 10 s of droplet impact. These optically transparent surfaces display excellent antifogging and self-cleaning properties. The magnitude of oleophobic-hydrophilic switching can be further enhanced by the incorporation of surface roughness to an extent that it reaches a sufficiently high level (water contact angle <10° and hexadecane contact angle >110°), which, when combined with the inherent ultrafast switching speed, yields oil-water mixture separation efficiencies exceeding 98%.

Impact of Picoliter Droplets on Superhydrophobic Surfaces with Ultralow Spreading Ratios

The impact of picoliter-sized water droplets on superhydrophobic CF(4) plasma fluorinated polybutadiene surfaces is investigated with high-speed imaging. Variation of the surface topography by plasmachemical modification enables the dynamics of wetting to be precisely controlled. Final spreading ratios as low as 0.63 can be achieved. A comparison of the maximum spreading ratio and droplet oscillation frequencies to models described in the literature shows that both are found to be much lower than theoretically predicted.

A Substrate-Independent Lift-Off Approach for Patterning Functional Surfaces

A lift-off method for creating multifunctional patterned surfaces has been devised. It entails consecutive pulsed plasmachemical deposition of a reactive bottom layer and a protective top release layer. By way of example, a bottom/top layer combination comprising pulsed plasma deposited poly(glycidyl methacrylate)/poly(pentafluorostyrene) has been shown to display selective adhesive lift-off of the latter. Application of a prepatterned adhesive template yields well-defined arrays of reactive epoxide functionality surrounded by a passive fluoropolymer background or vice versa.

Oxidative atomized spray deposition of electrically conductive poly(3,4-ethylenedioxythiophene)

Atomized spray deposition of 3,4-ethylenedioxythiophene monomer in the presence of triflic anhydride vapour yields electrically conducting poly(3,4-ethylenedioxythiophene) layers.

Atomized Spray Plasma Deposition of Structurally Well-Defined Bioactive Coatings

Structurally well-defined bioactive films have been prepared in a single solventless step by atomizing precursor molecules into a non-equilibrium electrical discharge. By way of example, atomized spray plasma deposition is used to form poly(alkyl acrylate) arrays for phospholipid immobilization, and poly(N-acryloylsarcosine methyl ester) protein-resistant surfaces.Graphical Abstract

Combining plasmachemical emulsion-templating with ATRP to create macroporous lipophilic surfaces

Well-defined alkyl chain side group polymer brushes have been tethered onto high surface area macroporous pulsed plasmachemical emulsion-templated poly(vinylbenzyl chloride) initiator layers (typically 600-700 m2 g(-1)) using atom transfer radical polymerisation (ATRP). Immobilisation of phospholipids onto these bioactive surfaces is found to occur through interdigitation, and the efficacy of lipid binding is governed by the alkyl side group chain length of the polymer brushes.

Nanoplasma surface electrification

Charge nanopatterning onto polymer film surfaces has been accomplished by using an SPM probe tip to create localised corona discharge electrification. The efficacy of surface charging is shown to strongly correlate to the polymer substrate hydrophilicity. This has led to a predictive structure-behaviour relationship.