Clarifying interfacial perturbation on polymer relaxation is important for polymer material development. Herein we investigated polymer–polymer interfacial perturbation on low molecular weight (MW) polystyrene (PS) thin film (15–180 nm) glass transition by depositing various polymers atop PS films. Overall, rubbery topcoats induced T g depression of PS thin film (below 60 nm), while glassy topcoats induced T g elevation of PS thin film (below 30 nm). Importantly, for the rubbery topcoat, T g perturbation strength is largely dependent on the T g difference between interfacial polymers and a larger T g difference would induce stronger perturbation, while for the glassy topcoat this dependence is inconspicuous. Meanwhile, the interfacial perturbation length during PS glass transition by rubbery topcoats is estimated to be around 8 nm, while it is considered to be about 3.5 nm for glassy topcoats. The different interfacial perturbation length induced by disparate topcoats was accounted for by their different perturbation strength on adjacent PS molecules and disparate interfacial roughness. The results can promote the understanding of polymer interfacial perturbation and benefit the design and development of polymer-based materials.

Patterned surfaces of responsive polymers find applications in diverse fields. However, it is still a great challenge to fabricate hierarchical patterns with long-range orders. Herein controllable hierarchical surface patterns that can be fabricated by combining nanoembossing techniques with the surface instability of supramolecular hydrogels are presented. Nanoembossed nanostripe arrays of polyethylene glycol (PEG)-based polyurethane-urea supramolecular hydrogels are fabricated and exposed to water, whereby the lateral expansion of nanostripes is confined and leads to the formation of folded in-plane or out-of-plane patterns depending on the aspect ratios. The direction of folds is perpendicular to the nanostripes. Both the amplitude and the wavelength of out-of-plane folds are proportional to the thickness of nanostripes. Therefore, hierarchical structures, in which one periodicity is defined by the nanoembossing processes and the other is determined by surface buckling, can be quickly fabricated in supramolecular hydrogel thin films.

Soft nano-imprinting lithography is used to fabricate PFO nanogratings.