Colored cotton fabrics with satisfactory color fastness as well as durable antibacterial and self-healing superhydrophobic properties are fabricated via a convenient solution-dipping method that involves the sequential deposition of branched poly(ethylenimine) (PEI), silver nanoparticles (AgNPs), and fluorinated decyl polyhedral oligomeric silsesquioxane (F-POSS) on cotton fabrics. The deposited AgNPs with tunable surface plasmon resonance endow the cotton fabrics with abundant color and and antibacterial ability. However, in general, water-soluble AgNPs cannot be firmly deposited onto cotton fabrics to endure the laundering process. The integration of self-healing superhydrophobicity into the cotton fabrics by depositing F-POSS/AgNP/PEI films significantly enhances the color fastness of the AgNPs against laundry and mechanical abrasion, while retaining the antibacterial property of the AgNPs. The F-POSS/AgNP/PEI-coated cotton fabric accommodates an abundance of F-POSS, which autonomically migrates to the cotton surface to repetitively restore its damaged superhydrophobicity. The self-healing superhydrophobicity of the F-POSS/AgNPs/PEI-coated cotton fabric guarantees long-term protection of the underlying AgNPs against laundry and abrasion and allows the cotton fabric to be cleaned by simple rinsing with water.

Optically transparent antibacterial films capable of healing scratches and restoring transparency are fabricated by exponential layer-by-layer assembly of branched polyethylenimine (bPEI)/poly(acrylic acid) (PAA) films and post-diffusion of cetyltrimethylammonium bromide micelles encapsulated with antibacterial agent triclosan. The triclosan-loaded bPEI/PAA transparent films can effectively inhibit the growth of gram-positive and gram-negative bacteria by the sustained release of triclosan molecules. Healing of multiple scratches on the triclosan-loaded bPEI/PAA films can be conveniently achieved by immersing the films in water or spraying water on the damaged films, which also fully restores their transparency. The self-healing ability of these transparent antibacterial films originates from the ability of bPEI and PAA to flow and recombine in the presence of water. The triclosan-loaded bPEI/PAA films have satisfactory mechanical stability under ambient conditions, and thus show potential for application as transparent protective films with antibacterial properties.

Near-infrared (NIR) light-driven bilayer actuators capable of fast, highly efficient, and reversible bending/unbending motions toward periodic NIR light irradiation are fabricated by exploiting the photothermal conversion and humidity-sensitive properties of polydopamine-modified reduced graphene oxide (PDA-RGO). The bilayer actuator comprises a PDA-RGO layer prepared by a filtration method, and this layer is subsequently spin-coated with a layer of UV-cured Norland Optical Adhesive (NOA)-63. Given the hydrophilicity of PDA, the PDA-RGO layer can absorb water to swell and lose water to shrink. The intrinsic NIR absorbance of RGO sheets convertes NIR light into thermal energy, which transfers the humidity-responsive PDA-RGO layer to be NIR light-responsive. Considering that the shape of the NOA-63 layer remains unchanged under NIR light, periodic NIR light irradiation leads to asymmetric shrinkage/expansion of the bilayer, which enables fast and reversible bending/unbending motions of the bilayer actuator. We demonstrate that compared with a poly(ethylenimine)-modified graphene oxide layer, the PDA-RGO layer is unique in fabricating highly efficient bilayer actuators. A NIR light-driven walking device capable of performing quick worm-like motion on a ratchet substrate is built by connecting two polyethylene terephthalate plates as claws on opposite ends of the PDA-RGO/NOA-63 bilayer actuator.

We report an innovative method for the fabrication of macroporous films with closed honeycomb-like pores of several micrometers by post-treatment of micrometer-thick poly(acrylic acid) (PAA)/poly(allylamine hydrochloride) (PAH) films. The precursor PAA/PAH films are fabricated by exponential layer-by-layer assembly of PAA and PAH, which produces PAA/PAH films with highly interpenetrated structures. We disclose that the high mobility of PAA and PAH, which originates from the highly interpenetrated film structures, allows a large-scale phase separation to take place upon post-treatment to produce micrometer-sized honeycomb pores. These macroporous PAA/PAH films can be conveniently released from substrates to produce free-standing films with satisfactory mechanical stability.