Adaptation of a Styrene-Acrylic Acid Copolymer Surface to Water.

Solid surfaces, in particular polymer surfaces, are able to adapt upon contact with a liquid. Adaptation results in an increase in contact angle hysteresis and influences the mobility of sliding drops on surfaces. To study adaptation and its kinetics, we synthesized a random copolymer composed of styrene and 11-25 mol% acrylic acid (PS/PAA).

Responsive Ionogel Surface with Renewable Antibiofouling Properties.

The synthesis of ionogels with a responsive, self-replenishing surface for combating biofouling is described. Ionogels are prepared by infiltrating poly(vinylidene fluoride-co-hexafluoropropylene) with binary mixtures of ionic liquids (IL): 1-octadecyl-3-methylimidazolium bis(trifluoromethyl sulfonyl)imide ([C C im][NTf ], melting point T = 55 °C) and 1-hexyl-3-methylimidazolium bis(trifluoromethyl sulfonyl)imide ([C C im][NTf ], T = -9 °C). The IL mixtures release spontaneously from the gel matrix and eventually crystallize on the surface.

Effects of Spacers on Photoinduced Reversible Solid-to-Liquid Transitions of Azobenzene-Containing Polymers.

Photoisomerization in some azobenzene-containing polymers (azopolymers) results in reversible solid-to-liquid transitions because trans- and cis-azopolymers have different glass transition temperatures. This property enables photoinduced healing and processing of azopolymers with high spatiotemporal resolution. However, a general lack of knowledge about the influence of the polymer structure on photoinduced reversible solid-to-liquid transitions hinders the design of such novel polymers.

Mesoscopic Correlation Functions in Heterogeneous Ionic Liquids.

A common feature of ionic liquids composed of cations with long aliphatic side chains is structural heterogeneities on the nanometer length scale. This so-called microphase separation arises from the clustering of aliphatic moieties. The temperature dependence of the liquid bulk structure was studied by small-angle X-ray and neutron scattering for a set of methylimidazolium ([CCim], [CCim]) based ionic liquids with tris(pentafluoroethyl)trifluorophosphate ([FAP]), bis(trifluoromethylsulfonyl)imide ([NTf]), and bis(nonafluorobutylsulfonyl)imide ([NNf]) anions.

Glass transition of poly(ethylmethacrylate) admixed and bound to nanoparticles.

The chain dynamics at the glass transition of poly(ethylmethacrylate) in the bulk is compared to that of mixtures of the polymer with nanoparticles by advanced NMR methods. In order to make the two components compatible, the particles were functionalized with the polymer itself. Particular emphasis is placed on the extended local chain conformations of this polymer accessible by (13)C NMR spectroscopy.

Nanoadhesion on rigid methyl-terminated biphenyl thiol monolayers: a high-rate dynamic force spectroscopy study.

Nanoadhesion on a self-assembled monolayer of 4-methyl-4'-mercaptobiphenyl is measured using a modified atomic force microscope. The dependence of the adhesion force on the loading rate is analyzed with the Dudko-Hummer-Szabo model, and the kinetic and interaction potential parameters for a single terminal group are extracted. The energy and location of the activation barrier suggest that the adhesion is dominated by van der Waals dispersion forces.

Micromechanical cantilever technique: a tool for investigating the swelling of polymer brushes.

Polymer brush coatings are well-known for their ability to tailor surface properties in a wide range of applications from colloid stabilization to medicine. In most cases, the brushes are used in solution. Consequently, efforts were expended to experimentally investigate or theoretically predict the swelling behavior of the brushes in solvents of different qualities.

Thermally induced sign change of Soret coefficient for dilute and semidilute solutions of poly(N-isopropylacrylamide) in ethanol.

We studied the thermal diffusion behavior of poly(N-isopropylacrylamide) (PNiPAM) in ethanol in a temperature range from T = 14.0 degrees C to T = 40.0 degrees C by means of thermal diffusion forced Rayleigh scattering.