Solution-printed organic semiconductors have emerged in recent years as promising contenders for roll-to-roll manufacturing of electronic and optoelectronic circuits. The stringent performance requirements for organic thin-film transistors (OTFTs) in terms of carrier mobility, switching speed, turn-on voltage and uniformity over large areas require performance currently achieved by organic single-crystal devices, but these suffer from scale-up challenges. Here we present a new method based on blade coating of a blend of conjugated small molecules and amorphous insulating polymers to produce OTFTs with consistently excellent performance characteristics (carrier mobility as high as 6.7 cm2 V−1 s−1, low threshold voltages of<1 V and low subthreshold swings <0.5 V dec−1). Our findings demonstrate that careful control over phase separation and crystallization can yield solution-printed polycrystalline organic semiconductor films with transport properties and other figures of merit on par with their single-crystal counterparts.

Despite extensive progress to engineer hydrogels for a broad range of technologies, practical applications have remained elusive due to their, until recently, poor mechanical properties and lack of fabrication approaches, which constrain active structures to simple geometries. We herein demonstrate a family of ionic composite hydrogels with excellent mechanical properties that can be rapidly 3D-printed at high resolution using commercial stereolithography technology. The new materials design leverages the dynamic and reversible nature of ionic interactions present in the system with the reinforcement ability of nanoparticles. The composite hydrogels combine within a single platform tunable stiffness, toughness, extensibility, and resiliency behavior not reported previously in other engineered hydrogels. In addition to their excellent mechanical performance, the ionic composites exhibit fast gelling under near-UV exposure, remarkable conductivity, and fast osmotically-driven actuation. The design of such ionic composites, which combine a range of tunable properties and can be readily 3D-printed into complex architectures provides opportunities for a variety of practical applications such as artificial tissue, soft actuators, compliant conductors and sensors for soft robotics.

In both biological and engineered systems, functioning at peak power output for prolonged periods of time requires thermoregulation. Here, we report a soft hydrogel-based actuator that can maintain stable body temperatures via autonomic perspiration. Using multimaterial stereolithography, we three-dimensionally print finger-like fluidic elastomer actuators having a poly-N-isopropylacrylamide (PNIPAm) body capped with a microporous (~200 micrometers) polyacrylamide (PAAm) dorsal layer. The chemomechanical response of these hydrogel materials is such that, at low temperatures (<30°C), the pores are sufficiently closed to allow for pressurization and actuation, whereas at elevated temperatures (>30°C), the pores dilate to enable localized perspiration in the hydraulic actuator. Such sweating actuators exhibit a 600% enhancement in cooling rate (i.e., 39.1°C minute−1) over similar non-sweating devices. Combining multiple finger actuators into a single device yields soft robotic grippers capable of both mechanically and thermally manipulating various heated objects. The measured thermoregulatory performance of these sweating actuators (~107 watts kilogram−1) greatly exceeds the evaporative cooling capacity found in the best animal systems (~35 watts kilogram−1) at the cost of a temporary decrease in actuation efficiency.

Sugar maple hemicellulosic hydrolysate containing 71.9 g/l of xylose was used as an inexpensive feedstock to produce polyhydroxyalkanoates (PHAs) by Burkholderia cepacia ATCC 17759. Several inhibitory compounds present in wood hydrolysate were analyzed for effects on cell growth and PHA production with strong inhibition observed at concentrations of 1 g/l furfural, 2 g/l vanillin, 7 g/l levulinic acid, and 1 M acetic acid. Gradual catabolism of lower concentrations of these inhibitors was observed in this study. To increase the fermentability of wood hydrolysate, several detoxification methods were tested. Overliming combined with low-temperature sterilization resulted in the highest removal of total inhibitory phenolics (65%). A fed-batch fermentation exhibited maximum PHA production after 96 h (8.72 g PHA/L broth and 51.4% of dry cell weight). Compositional analysis by NMR and physical-chemical characterization showed that PHA produced from wood hydrolysate was composed of polyhydroxybutyrate (PHB) with a molecular mass (M (N)) of 450.8 kDa, a melting temperature (T (m)) of 174.4°C, a glass transition temperature (T (g)) of 7.31°C, and a decomposition temperature (T (decomp)) of 268.6°C.

Additive manufacturing permits innovative soft device architectures with micron resolution. The processing requirements, however, restrict the available materials, and joining chemically dissimilar components remains a challenge. Here we report silicone double networks (SilDNs) that participate in orthogonal crosslinking mechanisms—photocurable thiol-ene reactions and condensation reactions—to exercise independent control over both the shape forming process (3D printing) and final mechanical properties. SilDNs simultaneously possess low elastic modulus ( E 100% < 700kPa) as well as large ultimate strains (d L/L 0 up to ~ 400 %), toughnesses ( U ~ 1.4 MJ·m −3 ), and strengths ( σ ~ 1 MPa). Importantly, the latent condensation reaction permits cohesive bonding of printed objects to dissimilar substrates with modulus gradients that span more than seven orders of magnitude. We demonstrate soft devices relevant to a broad range of disciplines: models that simulate the geometries and mechanical properties of soft tissue systems and multimaterial assemblies for next generation wearable devices and robotics.

The primary challenge regarding solid polymer electrolytes (SPEs) is the development of materials with enhanced mechanical modulus without sacrificing ionic conductivity. Here, we demonstrate that when stiff/rigid polymer nanoparticles that are thermodynamically miscible with a polymer are utilized in a blend with a liquid electrolyte, the elastic modulus and the ionic conductivity of the resulting SPEs increase compared to the linear polymer blend analogues. In particular, when poly­(methyl methacrylate), PMMA, nanoparticles, composed of high functionality star-shaped PMMA, were added to low molecular weight poly­(ethylene oxide), PEO, doped with bis­(trifluoromethane)­sulfonamide (LiTFSI), the resulting SPEs exhibit 2 orders of magnitude higher conductivity and 1 order of magnitude higher mechanical strength compared to their linear PMMA blend analogues. In addition, the former remain solidlike over an extended temperature range. Key to their performance is the morphology that stems from the ability of the PMMA nanoparticles to disperse within the liquid electrolyte host, allowing for the formation of a highly interconnected network of pure liquid electrolyte that leads to high ionic conductivity (comparable to that of the neat PEO electrolyte). The present strategy offers tremendous potential for the design of all-polymer electrolytes with optimized mechanical properties and ionic conductivity over a wide temperature window for advanced electrochemical devices.

For the next generation of safe and high energy rechargeable lithium metal batteries, we introduce nanostructured polymer particles of asymmetric miktoarm star copolymers as additives to liquid electrolytes for use as solid polymer electrolytes (SPE). The mechanical properties of the resulting SPEs are dramatically improved compared to the pure liquid electrolyte (the elastic modulus increased by up to 8 orders of magnitude), while the ionic conductivity was maintained close to that of the pure liquid electrolyte. In particular, the addition of 44 wt % miktoarm stars, composed of ion conducting poly­(ethylene oxide), PEO, arms that complement stiff insulating polystyrene arms, PS ((PS) n (PEO) n , where n = 30 the number of arms), in a low molecular weight PEO doped with lithium bis­(trifluoro­methane)­sulfonamide (LiTFSI), resulted in SPEs with a shear modulus of G′ ∼ 0.1 GPa and ion conductivity σ ∼ 10–4 S/cm. The SPEs show a strong decoupling between the mechanical behavior and the ionic conductivity as G′ remains fairly constant for temperatures up to the glass transition temperature of the PS blocks, while the conductivity monotonically increases reaching σ ∼ 10–2 S/cm. Our strategy offers tremendous potential for the design of all-polymer nanostructured materials with optimized mechanical properties and ionic conductivity over a wide temperature window for advanced lithium battery technology.

This article introduces a simple two‐stage method to synthesize and program a photomechanical elastomer (PME) for light‐driven artificial muscle‐like actuations in soft robotics. First, photochromic azobenzene molecules are covalently attached to a polyurethane backbone via a two‐part step‐growth polymerization. Next, mechanical alignment is applied to induce anisotropic deformations in the PME‐actuating films. Cross‐linked through dynamic hydrogen bonds, the PMEs also possess autonomic self‐healing properties without external energy input. This self‐healing allows for a single alignment step of the PME film and subsequent “cut and paste” assembly for multi‐axis actuation of a self‐folded soft‐robotic gripper from a single degree of freedom optical input.