Ten-Minute Synthesis of Highly Conductive Polymer Nanosheets on Ice Surfaces: Role of Ice Crystallinity.

Conducting polymers have been studied widely over the past decades for use as organic electrode materials owing to their high electrical conductivity and low-cost synthesis. Among the various synthesis methods reported, the recently established ice-assisted approach for developing conducting polymer nanosheets is regarded as an advanced technology that allows for easy fabrication in an eco-friendly manner. However, the role of the crystallinity of the underlying ice surface in determining the physicochemical properties of the conducting polymers remains unclear. Here, the electronic properties and packing structures of polyaniline (PANI) nanosheets formed on ice surfaces are studied by controlling the ice crystallinity. Intriguingly, the crystallinity of the PANI nanosheets resembles that of the ice surfaces, in that the anisotropic growth of the PANI crystals with a face-on orientation occurs preferentially on high-crystalline ice surfaces. In addition, it is found that the development of highly crystalline PANI nanosheets results in efficient charge transport, owing to polaron delocalization in PANI with extended chain conformations and the improvement in the degree of backbone ordering because of the preorganized aniline moieties on the ice surface.

Porous charged polymer nanosheets formed via microplastic removal from frozen ice for virus filtration and detection.

We developed a method for producing porous charged polymer nanosheets using frozen ice containing microplastics. Upon assessing SARS-CoV-2 filtration using nanosheets with 100 nm-sized pores, a high rejection rate of 96% was achieved. The charged surfaces of nanosheets further enabled the electrophoretic capture of the virus using a portable battery with additional real-time sensing capability.

Smart Bioinspired Actuators: Crawling, Linear, and Bending Motions through a Multilayer Design.

To fulfill the insatiable demand for wearable technologies, ionic electroactive polymer actuators have been entrenched as promising candidates that can convert low-input-voltage energy into high mechanical throughput. However, a ubiquitous trilayer design of actuators allows exclusively bending deformation and their highly nonlinear response restricts the true potential of low-voltage actuators for next-generation technology. Herein, we report an unprecedented multilayer design for soft actuators that enables complex deformations shown by skeletal muscles, mechanoreceptors, and plant roots in response to various environmental stimuli. Hierarchically ordered pores in a stretchable interlayer provide excellent electromechanical properties and fast charging kinetics, which enable linear motion by soft actuators at 3 V and under ambient conditions. Our actuators demonstrate astonishing levels of performance, including a 6.5% linear actuation strain, 0.8 s rapid switching speed, and 5000 cycle stable performance in air, producing a 4.2 mN linear blocking force at a ±3 V alternating square-wave voltage. This actuator design demonstrating a walkable spider capable of controlled back-and-forth propelling motion at low driving voltages provides the platform to envision a complex functionality using a portable battery as a power source for soft robotics, wearable exosuits, and biomimetic technologies.

Ice-assisted synthesis of functional nanomaterials: the use of quasi-liquid layers as nanoreactors and reaction accelerators.

The discovery of peculiar quasi-liquid layers on ice surfaces marks a major breakthrough in ice-related sciences, as the facile tuning of the reactions and morphologies of substances in contact with these layers make ice-assisted chemistry a low-cost, environmentally benign, and ubiquitous methodology for the synthesis of nanomaterials with improved functionality. Ice-templated synthesis of porous materials offers the appealing features of rapid self-organization and remarkable property changes arising from confinement effects and affords materials that have found a diverse range of applications such as batteries, supercapacitors, and gas separation. Moreover, much attention has been drawn to the acceleration of chemical reactions and transformations on the ice surface due to the freeze concentration effect, fast self-diffusion of surface water, and modulated surface potential energy. Some of these results are related to the accumulation of inorganic contaminants in glaciers and the blockage of natural gas pipelines. As an emerging theme in nanomaterial design, the dimension-controlled synthesis of hybrid materials with unprecedentedly enhanced properties on ice surfaces has attracted much interest. However, a deep understanding of quasi-liquid layer characteristics (and hence, the development of cutting-edge analytical technologies with high surface sensitivity) is required to achieve the current goal of ice-assisted chemistry, namely the preparation of tailor-made materials with the desired properties.

All-Solid-State Lithium-Organic Batteries Comprising Single-Ion Polymer Nanoparticle Electrolytes.

Advances in lithium battery technologies necessitate improved energy densities, long cycle lives, fast charging, safe operation, and environmentally friendly components. This study concerns lithium-organic batteries comprising bioinspired poly(4-vinyl catechol) (P4VC) cathode materials and single-ion conducting polymer nanoparticle electrolytes. The controlled synthesis of P4VC results in a two-step redox reaction with voltage plateaus at around 3.1 and 3.5 V, as well as a high initial specific capacity of 352 mAh g-1 . The use of single-ion nanoparticle electrolytes enables high electrochemical stabilities up to 5.5 V, a high lithium transference number of 0.99, high ionic conductivities, ranging from 0.2×10-3 to 10-3  S cm-1 , and stable storage moduli of >10 MPa at 25-90 °C. Lithium cells can deliver 165 mAh g-1 at 39.7 mA g-1 for 100 cycles and stable specific capacities of >100 mAh g-1 at a high current density of 794 mA g-1 for 500 cycles. As the first successful demonstration of solid-state single-ion polymer electrolytes in environmentally benign and cost-effective lithium-organic batteries, this work establishes a future research avenue for advancing lithium battery technologies.

Two-Dimensional Growth of Large-Area Conjugated Polymers on Ice Surfaces: High Conductivity and Photoelectrochemical Applications.

Polymerizing monomers on an atomically flat solid surface and air/water, solid/liquid, or liquid/liquid interface is now a rapidly emerging frontier. Dimension-controlled synthesis of π-conjugated polymers is of particular interest, which can be achieved by precise control of monomer distribution during the polymerization. The surface of ice allows rapid polymerization of monomers in the plane direction along the air-water interface to yield large-area two-dimensional sheet-like poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (2D sheet-like PEDOT:PSS) films with a thickness of ca. 30 nm. The persuasive role of ice chemistry is reflected in the high degree of crystallinity and superior conductivity of resultant PEDOT:PSS films. Excellent photoelectrochemical features were further disclosed when the ice-templated PEDOT:PSS films were coupled to quantum dots. Utilization of these polymer films in photovoltaic devices also resulted in excellent current density and power conversion efficiency. This work presents an innovative material technology that goes beyond traditional and ubiquitous inorganic 2D materials such as graphene and MoS2 for integrated electronic applications.

Tuning anhydrous proton conduction in single-ion polymers by crystalline ion channels.

The synthesis of high-conductivity solid-state electrolyte materials with eliminated polarization loss is a great challenge. Here we show a promising potential of single-ion block copolymers with crystalline protogenic channels as efficient proton conductors. Through the self-organization of zwitterion, imidazole, and polystyrene sulfonate with controlled dipolar interactions therein, the distance between neighboring proton donors and acceptors in ionic crystals, as well as the dipolar orientation in nanoscale ionic phases was precisely tuned. This allowed a markedly high static dielectric constant comparable to water and fast structural diffusion of protons with a low potential barrier for single-ion polymers. The optimized sample exhibited a high proton diffusion coefficient of 2.4 × 10-6 cm2 s-1 under anhydrous conditions at 90 °C.

Highly Catalytic Pt Nanoparticles Grown in Two-Dimensional Conducting Polymers at the Air-Water Interface.

We report a new approach to the synthesis of uniform, high areal density Pt nanocrystals supported by conducting polymers. The key strategy is the use of ice-templated, two-dimensional polyaniline nanosheets at the air-water interface as a platform for expediting Pt nucleation. Highly crystalline Pt nanoparticles with a narrow size distribution of 2.7 ± 0.3 nm and a high electrochemically active surface area of 94.57 m2 g-1 were obtained. Pt NPs were strongly anchored to the polyaniline nanosheets, and demonstrated high current densities, good durability for the methanol oxidation reaction, and excellent carbon monoxide tolerance, all of which are unprecedented. The idea established in this study could be applied to the production of a wide range of other catalysts with enhanced activities.

Intermittent Parathyroid Hormone Improves Bone Formation Around Titanium Implants in Osteoporotic Rat Maxillae.

PURPOSE: Parathyroid hormone (PTH) plays an important role in the treatment of osteoporosis due to its anabolic effect. In this study, PTH was administered intermittently to rats with ovariectomy-induced osteoporosis, titanium implants were placed into the rat maxillae, and the response of surrounding bone was evaluated. MATERIALS AND METHODS: A total of 30 female 8-week-old Sprague-Dawley rats were either ovariectomized to induce osteoporosis or sham operated. After 8 weeks, the upper right first molar was extracted and after a 4-week healing period an implant was placed. The animals were then divided into three groups: the PTH group (n = 10), which had been ovariectomized and received postimplant PTH; the OVX group (n = 10), which had been ovariectomized but did not receive postimplant PTH; and the control group (n = 10), which had been sham operated only (n = 10). Following implant placement, the rats in the PTH group received intermittent doses (three times a week) of PTH (30 µg/kg) subcutaneously in the dorsum. All the rats were sacrificed 4 weeks after implantation and specimens of the peri-implant maxillary bone were harvested, including the implant. Samples were evaluated by histomorphometric analysis and three-dimensional microcomputed tomography. RESULTS: Histomorphometric results showed that the mean bone area per tissue area (BA/TA) was 54.16% ± 2.2% in the PTH group and 45.24% ± 6.3% in the OVX group. The percentage of bone-to-implant contact (BIC) was 45.58% ± 9.4% in the PTH group and 32.00% ± 10.9% in the OVX group. Mean BA/TA and mean BIC values in the PTH group were higher than those in the OVX group; however, the differences were not statistically significant (P > .05). Microstructural data also showed differences between the groups. Bone volume was greater and trabecular bone was thicker in the PTH group than in the OVX group and more trabeculae were found in the PTH group. Bone mineral density was also higher in the PTH group. However, statistical analysis failed to show a significant difference between these two groups in any parameters other than trabecular thickness (P = .023). CONCLUSION: Despite the limitations of this study, intermittent PTH administration in humans may be helpful in accelerating new bone formation around implants. PTH treatment could improve clinical outcomes when dental implants are placed in jaws with low-quality bone.

Biosynthesis of rubradirin as an ansamycin antibiotic from Streptomyces achromogenes var. rubradiris NRRL3061.

The four overlapping cosmids from the rubradirin producer, Streptomyces achromogenes var rubradiris NRRL 3061, have 58 ORFs within a 105.6 kb fragment. These ORFs harbored essential genes responsible for the formation and attachment of four distinct moieties, along with the genes associated with regulatory, resistance, and transport functions. The PKS (rubA) and glycosyltransferase (rubG2) genes were disrupted in order to demonstrate a complete elimination of rubradirin production. The rubradirin biosynthetic pathway was proposed based on the putative functions of the gene products, the functional identification of sugar genes, and the mutant strains.