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Using adaptive soft materials to fabricate microstructured surfaces renders them with tunable topographic feature and thus controllable physical properties. Here, light responsive microstructured surfaces are reported with shape memory and tunable wetting behaviors; the surfaces are covered with micropillar arrays and constructed by lightly crosslinked azo-containing liquid crystalline network (LCN). UV light irradiation induces 25% contraction in length of the micropillars along their long axes and, as a consequence, the variations of topographic feature and wetting behavior of the surfaces. In addition, the LCNs exhibit shape memory properties, which can freeze the temporary topographic feature of microstructured surfaces (formed under UV irradiation and relatively high temperature) and enable application of their functionalities at mild conditions. This light responsiveness makes it feasible to remotely and precisely tune the local regions of microstructured surfaces, which should broaden the applications of adaptive surfaces in regulating the wetting, optical, and adhesion properties in selected regions.

Photolabile polymer brushes with tailored length containing a photoremovable protecting group (NVOC) are prepared via the SI-ATRP method. Upon light irradiation, the NVOC group is removed to generate controlled densities of free amine groups (PAMA) randomly distributed along the brush. The presence of the ionizable groups induces a photo-triggered swelling response. The swelling degree can be tuned by the irradiation dose. A dual (light and pH), tunable response is demonstrated.

Photoresponsive supramolecular gels with various applications are being constantly pursued; however, achieving well-defined morphology changes of gels via light irradiation remains a formidable challenge. In this study, a gel is prepared through halogen bond between azopyridine-containing Azopy-C10 and 1,4-tetrafluorodiiodobenzene. The gel exhibits gel-sol transition due to trans-cis isomerization of the azopyridine moiety upon UV irradiation. During this transition, the morphologies vary from flake to fluffy bobble-like and finally to peony-like with increasing exposure time, which is difficult to achieve in traditional assembly systems. The microstructure change is attributed to the variations of cis-isomer content and halogen-bonding strength. The supramolecular gel provides a novel method to achieve photomodulated morphologies and broadens the applications of such kind of materials, ranging from information storage to high-tech anticounterfeit.

Supramolecular hydrogels that are assembled through dynamic host-guest interactions have presented apparent potential in the construction of materials with promising performance. Herein, a photoregulated hydrogel cross-linked by host-guest interactions with multifunctions of high stretchability, strong toughness, and rapid self-healing property is reported. The hydrogel exhibits unique light-responsive property due to the introduction of two photoisomerized groups. For example, the stress-strain curve of the original hydrogel indicates 1020% rupture strain with the maximum tensile strain value of 214 kPa. Upon 365 nm light irradiation for an hour, its tensile strain increases to 15 times with lower tensile stress indicating a better stretchability. Moreover, the hydrogel is photochromic and surface patternable, where it can reversibly switch color between luminous yellow and brown while exposed to 365 and 440 nm light irradiation. It holds great promise for applying in self-recovering optically controlled and labeled elastic mechanical materials.

Thermosensitive poly(N-isopropylacrylamide) (PNIPAm)-coated gold nanoparticles (AuNPs) were prepared by self-assembly of the azobenzene-terminated PNIPAm on the surface of the α-cyclodextrin (α-CD)-capped AuNPs via the host-guest molecular recognition between α-CD and azobenzene. Reversible attachment-detachment of azobenzene-terminated PNIPAm on the surface of α-CD-capped AuNPs was achieved when subjected to visible and UV light irradiation alternately, which endowed thermosensitive AuNPs with tunable smart properties.

A photocleavable terpolymer hydrogel cross-linked with o-nitrobenzyl derivative cross-linker is shown to be capable of self-shaping without losing its physical integrity and robustness due to spontaneous asymmetric swelling of network caused by UV-light-induced gradient cleavage of chemical cross-linkages. The continuum model and finite element method are used to elucidate the curling mechanism underlying. Remarkably, based on the self-changing principle, the photosensitive hydrogels can be developed as photoprinting soft and wet platforms onto which specific 3D characters and images are faithfully duplicated in macro/microscale without contact by UV light irradiation under the cover of customized photomasks. Importantly, a quick response (QR) code is accurately printed on the photoactive hydrogel for the first time. Scanning QR code with a smartphone can quickly connect to a web page. This photoactive hydrogel is promising to be a new printing or recording material.

A simple lithographic process in conjunction with a novel biocompatible nonchemically amplified photoresist material was successfully used for cell patterning. UV light irradiation on selected regions of the nonchemically amplified resist film renders the exposed regions hydrophilic by the formation of carboxylic groups. Mouse fibroblast cells were found to be preferentially aligned and proliferated on the UV light exposed regions of the nonchemically amplified resist film where carboxylic groups were present.