Superhydrophobic surfaces are generally made by controlling the surface chemistry and surface roughness of various expensive materials, which are then applied by means of complex time-consuming processes. We describe a simple and inexpensive method for forming a superhydrophobic coating using polypropylene (a simple polymer) and a suitable selection of solvents and temperature to control the surface roughness. The resulting gel-like porous coating has a water contact angle of 160 degrees. The method can be applied to a variety of surfaces as long as the solvent mixture does not dissolve the underlying material.

Monolayers that are bonded via a covalent Si−C bond are prepared on a silicon(100) surface by reaction of a 1-alkene with the hydrogen-terminated silicon surface. The monolayers have been analyzed by infrared spectroscopy, X-ray reflectivity, and water contact angle measurements and display a remarkably high thermal stability. The reaction also works well for ω-functionalized 1-alkenes, provided that the functional group is properly protected. After formation of the monolayer, the protecting group can be easily removed without noticeable disturbance of the monolayer integrity, and the now reactive sites at the monolayer can be used for further functionalization, as has been shown in the case of ester-protected alcohol and carboxylic acids. Functional groups that are too close to the alkene moiety interfere with monolayer formation and yield disordered monolayers.

A simple globular-shaped liquid (octamethylcyclotetrasiloxane, OMCTS) was placed between two solid plates at variable spacings comparable to the size of this molecule and the linear shear viscoelasticity of the confined interfacial film was measured. Strong monotonic increase of the shear relaxation time, elastic modulus, and effective viscosity were observed at spacings less than about 10 molecular dimensions. Frequency dependence showed good superposition at different film thickness. The observed smooth transition to solidity is inconsistent with a first-order transition from bulk fluid to solidity.

Poly(2-alkyl-2-oxazoline)s can be regarded as pseudo-peptides or bioinspired polymers, which are available through living/controlled cationic polymerization and polymer ("click") modification procedures. Materials and solution properties may be adjusted via the nature of the side chain (hydrophilic-hydrophobic, chiral, bio-functional, etc.), opening the way to stimulus-responsive materials and complex colloidal structures in aqueous environments. Herein, we give an overview over the macromolecular engineering of polyoxazolines, including the synthesis of biohybrids, and the "smart"/bioinspired aggregation behavior in solution.

Using the Diels−Alder (DA) “click chemistry” strategy between anthracene and maleimide functional groups, two series of well-defined polystyrene-g-poly(ethylene glycol) (PS-g-PEG) and polystyrene-g-poly(methyl methacrylate) (PS-g-PMMA) copolymers were successfully prepared. The whole process was divided into two stages:  (i) preparation of anthracene and maleimide functional polymers and (ii) the use of Diels−Alder reaction of these groups. First, random copolymers of styrene (S) and chloromethylstyrene (CMS) with various CMS contents were prepared by the nitroxide-mediated radical polymerization (NMP) process. Then, the choromethyl groups were converted to anthryl groups via the etherifaction with 9-anthracenemethanol. The other component of the click reaction, namely protected maleimide functional polymers, were prepared independently by the modification of commercially available poly(ethylene glycol) (PEG) and poly(methyl methacrylate) (PMMA) obtained by atom transfer radical polymerization (ATRP) using the corresponding functional initiator. Then, in the final stage PEG and PMMA prepolymers were deprotected by retro-Diels−Alder in situ reaction by heating at 110 °C in toluene. The recovered maleimide groups and added anthryl functional polystyrene undergo Diels−Alder reaction to form the respective (PS-g-PEG) and (PS-g-PMMA) copolymers. The graft copolymers and the intermediates were characterized in detail by using 1H NMR, GPC, UV, fluorescence, DSC, and AFM measurements.

Great balls of fiber! Annealing of a dilute aqueous solution of poly(2‐isopropyl‐2‐oxazoline) above its cloud point leads to the formation of a coagulate in the form of crystalline nanofibers (see microscopy image). Directional crystallization, which occurs below the glass transition temperature of the polymer at 65 °C, is driven by hydrophobic and dipolar interactions in combination with a solvation effect.

The friction of dry self-assembled monolayers, chemically attached to a solid surface and comprising a well-defined interface for sliding, is compared to the case of two solids separated by an ultrathin confined liquid. The monolayers were condensed octadecyltriethoxysilane (OTE). The liquid was squalane (C,,H,,), a film 2.0 nm thick confined between parallel plates of mica. The method of measurement was a surface forces apparatus, modified for oscillatory shear. The principal observations were the same in both cases: (1) Predominantly elastic behavior in the linear response state was followed by a discontinuous transition to a mostly dissipative state at larger deformations. The elastic energy stored at the transition was low, of the order of 0.1 kT per molecule. This transition was exactly repeatable in repetitive cycles of oscillation and reversible with pronounced hysteresis. (2) The dissipative stress in the sliding state was almost independent of peak sliding velocity when this was changed over several decades. Significant (although smaller) elastic stress also persisted, which decreased with increasing deflection amplitude but was almost independent of oscillation frequency. (3) The adhesive energy in the sliding state was significantly reduced from that measured at rest. This similarity of friction in the two systems, dry and wet sliding, leads us to speculate that, similar to plastic deformation of solids, sliding in the confined liquid films is the result of slippage along an interface.

The transition from rest to sliding contact of atomically smooth solids separated by molecularly thin liquid films was studied. The films could be deformed nearly reversibly to a large fraction of the film thickness. The modulus of elasticity and yield stress were low, considerably less than for a molecular crystal or glass in the bulk. The transition to dissipative sliding was typically (but not always) discontinuous. The dissipative stress was then nearly velocity-independent. The similar response of monolayers strongly attached to the solid surfaces, presenting a well-defined interface for sliding, suggests that the physical mechanism of sliding may involve wall slip.