Multiple Dynamic Bonds-Driven Integrated Cathode/Polymer Electrolyte for Stable All-Solid-State Lithium Metal Batteries.

All-solid-state lithium metal batteries (LMBs) are considered as the promising higher-energy and improved-safety energy-storage systems. Nevertheless, the electrolyte-electrodes interfacial issues due to the limited solid physical contact lead to discontinuous interfacial charge transport and large interfacial resistance, thereby suffering from unsatisfactory electrochemical performance. Herein, we construct an integrated cathode/polymer electrolyte for all-solid-state LMBs under the action of polymer chains exchange and recombination originating from multiple dynamic bonds in our well-designed dynamic supramolecular ionic conductive elastomers (DSICE) molecular structure. The DSICE acts as polymer electrolytes with excellent electrochemical performance and mechanical properties, achieving the ultrathin pure polymer electrolyte thickness (12 µm). Notably, the DSICE also functions as lithium iron phosphate (LiFePO4 , LFP) cathode binders with enhanced adhesive capability. Such well-constructed Li|DSICE|LFP-DSICE cells generate delicate electrolyte-electrodes interfacial contact at the molecular level, providing continuous Li+ transport pathways and promoting uniform Li+ deposition, further delivering superior long-term charge/discharge stability (>600 cycles, Coulombic efficiency, >99.8 %) and high capacity retention (80 % after 400 cycles). More practically, the Li|DSICE|LFP-DSICE pouch cells show stable electrochemical performance, excellent flexibility and safety under abusive tests.

Electrospun cellulose-based conductive polymer nanofibrous mats: composite scaffolds and their influence on cell behavior with electrical stimulation for nerve tissue engineering.

The fabrication of scaffolds with suitable chemical, physical, and electrical properties is critical for nerve cell adhesion and proliferation. Recently, electrical stimulation on conductive polymers has been applied to construct functional nerve cell scaffolds. Herein, we prepared natural polymer (cellulose)/conductive polymer nanofibrous mats, i.e., electrospun cellulose (EC)/poly N-vinylpyrrole (PNVPY) and EC/poly(3-hexylthiophene) (P3HT) through an efficient in situ polymerization method. The surface immobilization was characterized by optical microscopy (OM), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, hydrophilicity, porosity, and cyclic voltammetry. The OM and SEM images showed that PNVPY formed polymer coatings and aggregated nanoparticles on the EC nanofibers, while P3HT only produced polymer coatings. Compared with pure EC mats, both the composite mats had increased thickness, higher porosity, and higher conductivity. Also, an increase in hydrophilicity was found for EC/P3HT. In vivo cytocompatibility of the undifferentiated PC12 cells showed that the EC/PNVPY and EC/P3HT scaffolds exhibited favorable cell activity, adhesion, and proliferation. Furthermore, the results of electrical stimulation experiments indicated that the EC/P3HT mats could effectively promote the proliferation of the PC12 cells more than the EC and EC/PNVPY mats. The findings suggest a positive outcome regarding the conductive polymer-modified EC/PNVPY and EC/P3HT nanofibrous mats in neural tissue engineering.

Polyacrylonitrile nanofibrous mat from electrospinning: Born with potential anti-fungal functionality.

Electrospun nanofibers have been found in many applications such as air/water filtration, performance apparel, drug delivery, and scaffold for tissue engineering and started to be integrated in commercial products, which leads to their exposure to environment. Electrospun nanofibrous material is a relatively new material to microorganism in nature and little is known about the biological implication of interactions between electrospun nanofibrous mats and cellular fungal cells. Herein the interaction between electrospun polyacrylonitrile (ESPAN) nanofibrous mat and representative non-pathogenic/pathogenic cellular yeasts (Saccharomyces cerevisiae and Candida albicans) was investigated. It is demonstrated for the first time that when these cellular yeasts, species of the kingdom fungi, were exposed to ESPAN nanofibrous mat, they exhibited lower growth rate, radical change to morphology, and reduced viability without presence of any chemical antifungal agent. These responses were distinct from the cellular interactions with other forms of PAN materials (e.g. solid film or microfibrous mat). Exploration of mechanism indicated that the interaction between yeast cell and electrospun nanofibrous mat is a complex phenomenon in which both nanofibrous morphology and fiber surface composition/property play significant roles. The inherent anti-yeast and potential anti-fungal functionality of ESPAN nanofibrous mat may make an immediate impact on environmental microorganism and could also benefit the next-generation material design to control microbial growth through solely physical contact.

Facile Preparation of Doxorubicin-Loaded and Folic Acid-Conjugated Carbon Nanotubes@Poly(N-vinyl pyrrole) for Targeted Synergistic Chemo-Photothermal Cancer Treatment.

We developed a bifunctional nanoplatform for targeted synergistic chemo-photothermal cancer treatment. The nanoplatform was constructed through a facile method in which poly(N-vinyl pyrrole) (PVPy) was coated on cut multiwalled carbon nanotubes (c-MWNTs); FA-PEG-SH was then linked by thiol-ene click reaction to improve the active targeting ability, water dispersibility, and biocompatibility and to extend the circulation time in blood. The PVPy shell not only enhanced the photothermal effect of c-MWNTs significantly but also provided a surface that could tailor targeting molecules and drugs. The resulting MWNT@PVPy-S-PEG-FA possessed high drug-loading ratio as well as pH-sensitive unloading capacity for a broad-spectrum anticancer agent, doxorubicin. Owing to its outstanding efficiency in photothermal conversion and ability in targeted drug delivery, the material could potentially be used as an efficient chemo-photothermal therapeutic nanoagent to treat cancer.

Synthesis and properties of flexible nanocable with carbon nanotube @ polymer hierarchical structure.

A multi-functional polymer-carbon nanotube (CNT) nanocable with a hierarchical structure is fabricated by grafting poly (glycidyl methacrylate) (PGMA) from the CNT surface via activators regenerated by electron transfer atom transfer radical polymerization. Multiple CNTs are arranged in parallel in the fabricated nanocable and exhibit strong binding force with sheathing PGMA. In situ mechanical and electrical tests conducted on an individual nanocable reveal its high flexibility and excellent surface insulation, with an electrical resistance of approximately 1 GΩ. On increasing the voltage to the nanocable's electrical breakdown point, nanoscale electrical trees are observed. Such degradation behavior is discussed in the wider context of breakdown mechanisms in polymer based CNTs.

A photocurable leaky dielectric for highly electrical insulating electrohydrodynamic micro-/nanopatterns.

This communication describes an innovative photocurable leaky dielectric for electrohydrodynamic patterning (EHDP). Based on the well-designed molecular structure, the material in its liquid state exhibits low viscosity, high homogeneity, and more importantly a leaky dielectric characteristic; meanwhile, UV light irradiation transforms it from a liquid leaky dielectric into a solid perfect dielectric instantaneously via an interfacial reaction. Two typical EHDP processes have confirmed that the beneficial properties of this material help to rapidly fulfill a higher aspect ratio and/or smaller feature size patterning compared to its perfect dielectric counterpart. Therefore, this material provides the potential in accessing high-performance EHDP towards fabricating electrically insulating micro-/nanostructures.

Preparation and properties of ion-imprinted hollow particles for the selective adsorption of silver ions.

Four kinds of silver ion-imprinted particles (Ag-IIPs) with different morphologies were prepared by the surface ion-imprinting technology (SIIT) and were used for the selective removal and concentration of silver ions from wastewater. The favorable adsorptivity and selectivity of Ag-IIPs for Ag(+) were confirmed by a series of adsorption experiments at a suitable pH value. The adsorption mechanism was elucidated by analyzing the adsorption isotherms, adsorption thermodynamics, and adsorption kinetics systematically. The Ag(+) adsorption onto the Ag-IIPs was well-described by the Langmuir isotherm model, and it was likely to be a monolayer chemical adsorption. This conclusion was also confirmed by the thermodynamic parameters. Moreover, the adsorption kinetics indicated that the adsorption rate would be controlled jointly by the intraparticle diffusion and the inner surface adsorption process, and the latter process was generally associated with the formation and breaking of chemical bonds. Finally, the effects of different morphologies of the Ag-IIPs for Ag(+) adsorption were also investigated. In aqueous solution, the adsorptivity of the Ag(+) ion-imprinting single-hole hollow particles (Ag-IISHPs) for Ag(+) was highest (80.5 mg g(-1)) because of a specific morphology that features a single hole in the shell. In an oil-water mixture, Ag(+) in the water phase could be adsorbed efficiently by the Ag(+) ion-imprinting Janus hollow particles (Ag-IIJHPs), with emulsifiability originating from the Janus structure.

Preparation, characterization, and properties of hollow Janus particles with tailored shapes.

As compared to the traditional solid Janus particles, the hollow Janus particles have inspired growing interests due to their diverse potential applications. Herein, the novel hollow Janus particles with elephant trunk-like and acorn-like shapes were prepared by seed emulsion polymerization. In contrast to traditional template methods, the hollow structure was obtained during the preparation by one-step swelling method. The shapes and internal structures of hollow Janus particles were confirmed, and the compositions were identified too. Some critical influences on the morphology control were investigated, that is, the surface modification, the amount of surfactant, and cross-linking agent concentrations. It was inferred that the balance of hydrophilicity and hydrophobicity and the effective phase separation were important for preparing the hollow Janus particles with tailored shapes. Finally, amphiphilic properties of hollow Janus particles were demonstrated by emulsifying oil-water mixture.

Enhancing Mechanical Properties and Microstructures of Mass-Manufactured Sand Concrete by Incorporating Granite Powder.

The production of manufactured sand and stone processing can cause dust pollution due to the generation of a significant amount of stone powder. This dust (mainly granite powder) was collected and incorporated as a cement replacement into mass-manufactured sand concrete in order to enhance the mechanical properties and microstructures. The heat of the hydration was measured by adding the granite powder into the cementitious material system. The mechanical properties, autogenous shrinkage, and pore structures of the concrete were tested. The results showed that the mechanical strength of the concrete increased first and then decreased with the increase in granite powder content. By replacing the 5% cement with the granite powder, the 28 d compressive and flexural strength increased by 17.6% and 20.9%, respectively. The autogenous shrinkage was mitigated by the incorporation of the 10% granite powder and decreased by 19.7%. The mechanism of the granite powder in the concrete was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP). The porosity decreased significantly within the 10% granite powder. A microstructure analysis did not reveal a change in the type of hydration products but rather that the granite powder played a role in the microcrystalline nucleation during the hydration process.

Silver nanoparticles in hyperbranched polybenzobisthiazole: synthesis and characterization.

Silver (Ag) nanoparticles were successfully synthesized in hyperbranched polybenzobisthiazoles (HBPBZTs) matrices using a reductive technique. The synthesized Ag nanoparticles were characterized through different spectroscopic and analytical techniques, such as FTIR, XRD, TGA, TEM, UV-vis, and fluorescence spectra. The results showed that the synthesized Ag-HBPBZT nanocomposites exhibited excellent thermostability and the Ag nanoparticles represented face-centered cubic crystal structures. It was interesting that these nanoparticles were soluble in DMSO. The Ag nanoparticles prepared using amino and sulfydryl-terminated HBPBZT (hbp3) as template and stabilizer had smaller sizes, more regular shapes, and narrower size distributions than those prepared using hbpl and hbp2 as templates and stabilizers. The Ag-HBPBZT nanocomposites had UV-vis absorptions at approximately 341 nm to 361 nm which were attributable to the surface plasmon resonance of the Ag nanoparticles. These nanocomposites emitted a strong blue light in DMSO solution. The prepared Ag-HBPBZT nanocomposites are potentially useful in the area of blue light emission.

Pattern formation in thin polymeric films via electrohydrodynamic patterning.

The free surface of a thin polymeric film is often unstable and deforms into various micro-/nano-patterns under an externally applied electric field. This paper reviews a recent patterning technique, electrohydrodynamic patterning (EHDP), a straightforward, cost-effective and contactless bottom-up method. The theoretical and numerical studies of EHDP are shown. How the characteristic wavelength and the characteristic time depend on both the external conditions (such as voltage, film thickness, template-substrate spacing) and the initial polymer properties (such as rheological property, electrical property and surface tension) is theoretically and experimentally discussed. Various possible strategies for fabricating high-aspect-ratio or hierarchical patterns are theoretically and experimentally reviewed. Aligning and ordering of the anisotropic polymers by EHDP is emphasized. A perspective, including novelty and limitations of the methods, particularly in comparison to some conventional patterning techniques, and a possible future direction of research, is presented.

Effect of Sulfate Concentration on Chloride Diffusion of Concrete under Cyclic Load.

The existence of chloride ions, sulfate ions, and vehicle dynamic loads may lead to a shortened service life and premature failure of the road and bridge structures in northwestern China. Immersed in a dual-salt solution while simultaneously applying cyclic flexural loads, the free chloride ion concentration and erosion depth in concrete specimens were measured. The influence of the sulfate concentration on the apparent surface chloride concentration (Cs) and apparent diffusion coefficient (Dapp) was studied. An exponential model was used to fit the Cs, and the influence of sulfate concentration on the Cs was analyzed. The result showed that cyclic loading and solution concentration were two primary factors affecting chloride diffusion. Meanwhile, compared with the emersion conditions, dynamic loading would induce significantly accelerated chloride ion penetration. Under the coupling effect of sulfate and dynamic loading, as the sulfate concentration increased, the chloride ion concentration and erosion depth were both decreased. The existence of sulfate ions improved the chloride ion penetration resistance of concrete. The results provide insight in designing concrete in regions where multiple salt ingression (sulfate and chloride) is a major durability issue of the structures.

Polypyrrole Nanomaterials: Structure, Preparation and Application.

In the past decade, nanostructured polypyrrole (PPy) has been widely studied because of its many specific properties, which have obvious advantages over bulk-structured PPy. This review outlines the main structures, preparation methods, physicochemical properties, potential applications, and future prospects of PPy nanomaterials. The preparation approaches include the soft micellar template method, hard physical template method and templateless method. Due to their excellent electrical conductivity, biocompatibility, environmental stability and reversible redox properties, PPy nanomaterials have potential applications in the fields of energy storage, biomedicine, sensors, adsorption and impurity removal, electromagnetic shielding, and corrosion resistant. Finally, the current difficulties and future opportunities in this research area are discussed.

Phase-locked constructing dynamic supramolecular ionic conductive elastomers with superior toughness, autonomous self-healing and recyclability.

Stretchable ionic conductors are considerable to be the most attractive candidate for next-generation flexible ionotronic devices. Nevertheless, high ionic conductivity, excellent mechanical properties, good self-healing capacity and recyclability are necessary but can be rarely satisfied in one material. Herein, we propose an ionic conductor design, dynamic supramolecular ionic conductive elastomers (DSICE), via phase-locked strategy, wherein locking soft phase polyether backbone conducts lithium-ion (Li+) transport and the combination of dynamic disulfide metathesis and stronger supramolecular quadruple hydrogen bonds in the hard domains contributes to the self-healing capacity and mechanical versatility. The dual-phase design performs its own functions and the conflict among ionic conductivity, self-healing capability, and mechanical compatibility can be thus defeated. The well-designed DSICE exhibits high ionic conductivity (3.77 × 10-3 S m-1 at 30 °C), high transparency (92.3%), superior stretchability (2615.17% elongation), strength (27.83 MPa) and toughness (164.36 MJ m-3), excellent self-healing capability (~99% at room temperature) and favorable recyclability. This work provides an interesting strategy for designing the advanced ionic conductors and offers promise for flexible ionotronic devices or solid-state batteries.

[Corrosive degradation of magnesium and its alloy as endovascular stent].

Magnesium and its alloy are used for the most potential endovascular stent material due to their excellent mechanical capabilities, adjustable corrosive properties, the little side effects of the materials and their degradation products. The in vito degradation rate of the current magnesium and its alloy as endovascular stent is very quickly so that the artery is not supported long enough to prevent negative remodeling. This review detailed the approach to enhance the corrosion resistance, in vitro corrosion rate measurement of magnesium and its alloy, as well as the in vito corrosion research when as the endovascular stents.

Facile preparation of pH/redox dual-responsive biodegradable polyphosphazene prodrugs for effective cancer chemotherapy.

In order to maximize the therapeutic effect and and minimize the systemtic side effect of the small molecule anticancer drugs, biodegradable drug delivery systems (DDSs) that respond to tumor microenvironment (TME) have attracted significant attention. Herein, a novel redox/pH dual-responsive and biodegradable polyphosphazene (PPZ) nano-prodrugs have been prepared via one-pot crosslinking of vanillin modified DOX (VMD, acid-sensitive) and 4,4'-dihydroxydiphenyl disulfide (HPS, GSH-responsive) with hexachlorocyclotriphosphazene (HCCP). The phenol groups of the as-synthesized VMD and HPS have high nucleophilic substitution activity towards HCCP under base catalyst and afforded PPZ nano-prodrugs, denoted as HCCP-VMD-HPS, with a high drug loading ratio of up to 56.4 %. As expected, the skeleton of the PPZ consisting of imine bonds in VMD and the disulfide bonds in HPS and cyclotriphosphazenes inclined to be decomposed in low pH conditions and high level of GSH environments. The antitumor drug DOX was found to be controlled released in TME conditions (extracellular, pH∼6.8 and endosomes, lysosomes pH∼5.0 with ∼10 mM GSH), rather than neutral physiological conditions (pH 7.4 with ∼20 µM GSH). Moreover, the resulting HCCP-VMD-HPS nano-prodrug have obvious cytotoxicity to cancer cells while a negligible side effect to normal cells. We therefore believe that the prepared redox/pH dual-responsive and biodegradable PPZ DDSs have great potential in various field.

Crystallization Control of N,N'-Dioctyl Perylene Diimide by Amphiphilic Block Copolymers Containing poly(3-Hexylthiophene) and Polyethylene Glycol.

The preparation of micron- to nanometer-sized functional materials with well-defined shapes and packing is a key process to their applications. There are many ways to control the crystal growth of organic semiconductors. Adding polymer additives has been proven a robust strategy to optimize semiconductor crystal structure and the corresponding optoelectronic properties. We have found that poly(3-hexylthiophene) (P3HT) can effectively regulate the crystallization behavior of N,N'-dioctyl perylene diimide (C8PDI). In this study, we combined P3HT and polyethylene glycol (PEG) to amphiphilic block copolymers and studied the crystallization modification effect of these block copolymers. It is found that the crystallization modification effect of the block copolymers is retained and gradually enhanced with P3HT content. The length of C8PDI crystals were well controlled from 2 to 0.4 µm, and the width from 210 to 35 nm. On the other hand, due to the water solubility of PEG block, crystalline PEG-b-P3HT/C8PDI micelles in water were successfully prepared, and this water phase colloid could be stable for more than 2 weeks, which provides a new way to prepare pollution-free aqueous organic semiconductor inks for printing electronic devices.

Effects of surface condition of conductive electrospun nanofiber mats on cell behavior for nerve tissue engineering.

Electrospun nanofibrous scaffold is a promising implant for peripheral nerve regeneration. Herein, to investigate the effect of surface morphological features and electrical properties of scaffolds on nerve cell behavior, we modified electrospun cellulose (EC) fibrous mats with four kind of soluble conductive polymers derivates (poly (N-(methacryl ethyl) pyrrole) (PMAEPy), poly (N-(2-hydroxyethyl) pyrrole) (PHEPy), poly (3-(Ethoxycarbonyl) thiophene) (P3ECT) and poly (3-thiophenethanol) (P3TE)) by an in-situ polymerization method. The morphological characterization showed that conductive polymers formed aggregated nanoparticles and coatings on the EC nanofibers with the increased fiber diameter further affected the surface properties. Compared with pure EC scaffold, more PC12 cells were adhered and grown on modified mats, with more integral and clearer cell morphology. The results of protein adsorption study indicated that modified EC mats could provide more protein adsorption site due to their characteristic surface morphology, which is beneficial to cell adhesion and growth. The results in this study suggested that these conductive polymers modified scaffolds with special surface morphology have potential applications in neural tissue engineering.

Formation of Stereocomplex Crystal and Its Effect on the Morphology and Property of PDLA/PLLA Blends.

Stereocomplex-polylactic acid (SC-PLA) is obtained in poly(D-lactic) acid/poly(L-lactic) acid (PDLA/PLLA) blends under adjusting processing conditions. It is found that the degree of crystallinity of overall SC-PLA is up to 43.7% in PDLA/PLLA blends of 1:1 mass ratio. Formation of stereocomplex (SC) crystals forces molecular chains in the blends to be more closely arranged and further enhances interaction between molecular chains, thus forming a physical cross-linking network in the SC crystals, resulting in the blends having a special microstructure. The mechanism of formation of the SC crystal physical cross-linking network is elucidated by dielectric spectroscopy, and the relationships between homocomplex (HC) crystals, SC crystals, and amorphous regions in the blends are also analyzed. Interestingly, mechanical properties of the blends are significantly improved due to formation of an SC crystal cross-linking network.

Electrospun natural polymer and its composite nanofibrous scaffolds for nerve tissue engineering.

Attributed to the excellent biocompatibility and desirable mechanical properties to natural tissue, natural polymer-based electrospun nanofibers have drawn extensive research interests in tissue engineering. Electrospun nanofibers have been explored as scaffolds in tissue engineering to modulate cellular behavior. Also, electrospun nanofiber matrices have morphological similarities to the natural extra-cellular matrix (ECM). Natural polymer and its composite nanofiber mats are the promising candidates in governing nerve cells growth and nerve regeneration due to their unique characteristics such as high permeability, stability, porosity, suitable mechanical performance and excellent biocompatibility. In this review, the progress in electrospun natural polymers and its composite nanofibers scaffold for neural tissue engineering are presented. The influences of fiber orientation and electrical stimulation on the nerve cell behavior and neurite growth are systematically summarized. Furthermore, the current application of natural polymer composite scaffold as in vivo implantable device for nerve regeneration is also discussed (see Figure 1).