Mobility gradients yield rubbery surfaces on top of polymer glasses

Direct Visualization and Characterization of Interfacially Adsorbed Polymer atop Nanoparticles and within Nanocomposites

“…For instance, at t ann ∼ 0.5 h, the observed T g was only 1.5 ± 1.9 K lower than, and therefore within the error of, the bulk value. Beyond short annealing times, the T g of in situ NPs generally decreased with increasing t ann until stabilizing when t ann ≥ 10 h. Comparing the T g of adsorbed layers of the corresponding t ann atop analogous isolated and redispersed NPs indicated that free surface effects dominated at short adsorption times, as the presence of a matrix induced near complete recovery of bulk T g . The degree of recoveryand hence the effect of the free interfaceshrinks until disappearing completely at t ann ≥ 10 h, where it can be deduced that the chain density and degree of anchoring are sufficient to restrict the enhanced mobility typical of the free interface.…”

Temperature-dependent soft wetting on amorphous, uncrosslinked polymer surfaces

“…In this domain, the viscoelastic response is controlled by the chain diffusing on length scales of the order of its own size. The deformation of the polymer film h(t) can be considered to scale as the mean square displacement (MSD) of the polymer chains, which is proportional to the time elapsed: 43 h 0 (t) B MSD B D(t)t. Thus, in the Rouse limit, h 0 (t R ) B D Rouse (t)t B t 1/2 . Beyond Rouse timescales, reptation modes dominate and the ridge is predicted to grow as h 0 (t rep ) B D c t B t.…”

“…40,41 On the other hand, studies on uncrosslinked, polymeric melts are limited, especially for wetting ridges larger than a few hundred nanometers at temperatures well above its glass transition temperature (T g ). [42][43][44] Hence, the following questions remain: Can the linear rheology of a polymer melt help predict the growth rates of a wetting ridge? How do the viscoelastic properties of the polymer melt describe the shape of the wetting ridge profile?…”

Thermoresponsive ionogels with switchable adhesion in air and aqueous environments induced by LCST phase behavior

“…water) that is immiscible with the substrate is placed on the ionogel surfaces, a higher surface-wetting ridge can be achieved on the ionogel surfaces with lower surface rigidity ( i.e. better deformability) 33 thus, yielding a higher WCA for an ionogel with lower crosslinking density. On the other hand, an excessively low crosslinking density (0.1 mol%) will weaken the solvent binding ability of PBA network, which will inevitably lead to a leakage of solvent (even if it is a small amount).…”