Responsive polymer thin films

Responsive polymer thin films play an important role as structural components in the emerging fields of soft actuators, wearable electronics, and biomedical devices. These are capable changing their physical and/or chemical properties significantly response to environmental stimuli, such temperature, light, pH, magnetic fields, ion strength. The integration multifunctional designs networks enables these possess advanced capabilities, including, but not limited to, structure color, self-healing, adhesion, conductivity, antimicrobial properties, antifatigue properties. Polymer hydrogel typically thinner than bulk materials, ranging from nanometers several hundred micrometers, usually made up layers natural or synthetic polymers. can be free-standing coated on substrates. They offer faster times, high flexibility, good adaptivity, versatility via integrating with other functional materials. This special issue responsive collects a series review articles that detail latest progress this rapidly developing field, well original research propose novel approaches tackle practical challenges. article by Dong et al. provides comprehensive overview recent fabrication application films. authors focus two main areas: (i) methods used fabricate films, (ii) various applications biomedicine technologies. Hydrogel controllable thickness, fast compliance, tunable mechanical ideal for use artificial muscles, wound dressing, construction actuators flexible electronics. also highlights current challenges, future perspectives development Yang reported successful self-healable, electromagnetic interference (EMI) shielding composite exhibit dual responsiveness temperature strain. To create team incorporated carbon nanotubes into hydroxyl-terminated polybutadiene (HTPB), which was dynamically crosslinked boric acid (BA). HTPB-BA substrate showed excellent self-healing ability at room facilitating autonomous recovery electric conductivity strength Dual strain observed resistance actively variation In addition, exhibited EMI ability, effectiveness beyond 28 dB, making them commercial applications. efficiency found temperatures. responsive, shielding, self-healable have broad potential electronics protection sensitive instruments. Amphiphilic block copolymer (BCP) thick stimuli-responsive pores promising candidates next-generation ultrafiltration (UF) membranes, due stimuli-responsive, smart nanochannels facilitate removal fouling, among biggest challenges membrane technology. Bouzit prepared well-defined, polystyrene-block-poly(2-vinylpyridine)-block-poly(N-isopropylacrylamide) (PS-b-P2VP-b-PNIPAM) terpolymer using reversible addition-fragmentation chain transfer polymerization. combination nonsolvent-induced phase separation process solvent vapor annealing treatment produce nanostructured pH- thermo-double ABC-type, BCP NIPS-made PS-b-P2VP-b-PNIPAM film, comprising microporous spinodal-type network substructure topped dense layer poorly defined nanopores, transformed monolith composed entirely well-ordered, perforated lamellar (PL) upon exposure chloroform vapor. PL-structured monoliths, show permeance cyclability highly desirable manufacturing smart, separation-based UF materials transition pore state hydrophilic hydrophobic (and vice versa), leading much more efficient detachment foulants during cleaning process. Dolmat developed method dynamic assembly hydrogen-bonded multilayers (poly(N-vinylpyrrolidone/poly(methacrylic acid)) [PVPON/PMAA]) compared it static multilayers. multilayers, planar is shaken adsorption, leads 15-times deposition coatings multilayer thickness roughness were approximately 30% larger those measured spectroscopic ellipsometry atomic force microscopy. researchers examined film growth, wettability, hydration, pH stability minimally affected mode. discovered release solution (either membranes capsule shells), molecular rearrangements resulted decreased both findings aid rapid synthesis thicker sensing controlled delivery Poly(vinylidene fluoride) (PVDF) has garnered significant attention decades its particularly pyro- piezo-electricity, linked electro-active β-phase PVDF. production β-PVDF through stretching nonpolar α-PVDF been reported, impact changes spin-coated PVDF unclear. study Pilla al., freestanding investigated effects thermal in-plane anisotropy. Full-field deformation under situ tensile loading, conjunction digital image correlation observe correlations between stress–strain behavior β-PVDF/α-PVDF stretch-induced transformation α-PVDF. annealed higher failure (~35 MPa ~5.5) (~10 ~0.45). Fourier transform infrared Raman spectroscopy confirm caused stretch ratio ~1.2. Furthermore, suggested anisotropy spin-coating unique Janus two-dimensional (2D) polymeric asymmetric surfaces, make biosensors, catalysts, drug systems. paper, Zhao successfully constructed micro/macro-scale polypeptoid-based 2D structures air–water interface evaporation-induced interfacial self-assembly amphiphilic poly(ethylene glycol)-b-poly(N-(2-phenylethyl) glycine) (PEG-b-PNPE). Initially, PEG-b-PNPE assembled monolayer uniform ~2.5 ± 0.1 nm, then mechanically compressed bilayer Langmuir–Blodgett (LB) technology increasing surface pressure critical collapse pressure. resulting nanostructure spanned hundreds microns dimensions, wettability air water sides, determined dynamic/static optical contact angle/interface tensiometer. evolution further tracked microscope. able prepare macroscopic diameter ~3.5 mm same methods. nanoscience biomedicine, results provide valuable contribution field another example, Kashem high-performance poly(diallyldimethylammonium chloride) (PDDA) poly(acrylic acid) (PAA) spin-spray-assisted layer-by-layer (SSA-LbL) assembly. SSA-LbL timesaving, homogeneous tens micrometer range conventional immersive method, produces nanometer range. When scratches occurred, displayed quick durable capability, thanks movement polyelectrolyte complex chains scratch edges. effectively blocked UV rays incorporating graphene oxide (GO) titanium dioxide (TiO2) nanoparticles UV-blocking additives. Because feature PDDA/PAA molecules, antifog characteristics different conditions. effect GO TiO2 nanoparticle concentration UV-protection identified optimum solutions producing UV-blocking, antifogging features. Silk renowned “queen fibers” lightness, smoothness, luster. A Zhu easy care silk fabrics crosslinking thermo-responsive onto surface. copolymer—poly(N-isopropylacrylamide-co-oligo[ethylene glycol] methyl ether methacrylate-co-ethylene glycol methacrylate) (P(NM-co-OA300-co-EA360))—was synthesized sequential atom radical By 1,2,3,4-butanetetracarboxylic crosslinker, thermos-responsive P(NM-co-OA300-co-EA360) placed fabric around 46 °C. reduces attachment lipophilic stains stain removal. 30-s rinse deionized 25 °C (below temperature) remove 60% stains. Moreover, outdoor activities drying, becomes hydrophobic, allowing molecules quickly evaporate fabrics; drying 25% without film. suitable designing silk-based clothing. years, advancements morph shapes, taking inspiration nature. One noteworthy example work Peeketi who new type thin-film-based bioinspired actuator. Drawing calla lily, they demonstrated splay-nematic liquid crystal tapered actuator flat cone, mimicking blooming lily flower. Using finite element simulations experiments, produced conical tubes. analyzed influence tapering alignment orientations respect edge cones simulations, design splayed alignments oriented 45 optimal choice forming collection offers glimpse many works published Journal Science Our aim summary selected publications, will, we hope, inspire readers develop solve fundamental problems explore devices We thank all authors, reviewers, editorial staff contributions issue. Wei Li Associate Professor Chemical Engineering Department Texas Tech University. He obtained his PhD Chemistry Materials University Toronto. Natural Sciences Research Council Canada (NSERC) Postdoctoral Fellow MIT. Dr. Li's combines microfluidics nanoassembly techniques microdevices biological, optical, energy Jouha Min Assistant Michigan. MIT, postdoctoral experience Harvard Medical School/Massachusetts General Hospital. Min's group focuses biomaterials biosensors engineering principles, goal creating robust health cancer life-threatening infectious diseases.