3D Cationic Polymeric Network Nanotrap for Efficient Collection of Perrhenate Anion from Wastewater.

Rhenium is one of the most valuable elements found in nature, and its capture and recycle are highly desirable for resource recovery. However, the effective and efficient collection of this material from industrial waste remains quite challenging. Herein, a tetraphenylmethane-based cationic polymeric network (CPN-tpm) nanotrap is designed, synthesized, and evaluated for ReO4- recovery. 3D building units are used to construct imidazolium salt-based polymers with positive charges, which yields a record maximum uptake capacity of 1133 mg g-1 for ReO4- collection as well as fast kinetics ReO4- uptake. The sorption equilibrium is reached within 20 min and a kd value of 8.5 × 105 mL g-1 is obtained. The sorption capacity of CPN-tpm remains stable over a wide range of pH values and the removal efficiency exceeds 60% for pH levels below 2. Moreover, CPN-tpm exhibits good recyclability for at least five cycles of the sorption-desorption process. This work provides a new route for constructing a kind of new high-performance polymeric material for rhenium recovery and rhenium-contained industrial wastewater treatment.

New Insight into the Synthesis of Large-Pore Ordered Mesoporous Materials.

Ordered mesoporous materials (OMMs) have received increasing interest due to their uniform pore size, high surface area, various compositions and wide applications in energy conversion and storage, biomedicine and environmental remediation, etc. The soft templating synthesis using surfactants or amphiphilic block copolymers is the most efficient method to produce OMMs with tailorable pore structure and surface property. However, due to the limited choice of commercially available soft templates, the common OMMs usually show small pore size and amorphous (or semicrystalline) frameworks. Tailor-made amphiphilic block copolymers with controllable molecular weights and compositions have recently emerged as alternative soft templates for synthesis of new OMMs with many unique features including adjustable mesostructures and framework compositions, ultralarge pores, thick pore walls, high thermal stability and crystalline frameworks. In this Perspective, recent progresses and some new insights into the coassembly process about the synthesis of OMMs based on these tailor-made copolymers as templates are summarized, and typical newly developed synthesis methods and strategies are discussed in depth, including solvent evaporation induced aggregation, ligand-assisted coassembly, solvent evaporation induced micelle fusion-aggregation assembly, homopolymer assisted pore expanding and carbon-supported crystallization strategy. Then, the applications of the obtained large-pore OMMs in catalysis, sensor, energy conversion and storage, and biomedicine by loading large-size guest molecules (e.g., protein and RNA), precious metal nanoparticles and quantum dots, are discussed. At last, the outlook on the prospects and challenges of future research about the synthesis of large-pore OMMs by using tailor-made amphiphilic block copolymers are included.

Soft-shear induced phase-separated nanoparticle string-structures in polymer thin films.

Application of shear stress has been shown to unidirectionally orient the microstructures of block copolymers and polymer blends. In the present work, we study the phase separation of a novel nanoparticle (NP)-polymer blend thin film system under shear using a soft-shear dynamic zone annealing (DZA-SS) method. The nanoparticles are densely grafted with polymer chains of chemically dissimilar composition from the matrix polymer, which induces phase separation upon thermal annealing into concentrated nanoparticle domains. We systematically examine the influence of DZA-SS translation speed and thus the effective shear rate on nanoparticle domain elongation and compare this with the counterpart binary polymer blend behavior. Unidirectionally aligned nanoparticle string-domains are fabricated in the presence of soft-shear in confined thin film geometry. We expect this DZA-SS method to be applicable to various NP-polymer blends towards unidirectionally aligned nanoparticle structures, which are important to functional nanoparticle structure fabrication.

Characteristics estimation of natural fibre reinforced plastic composites using deep multi-layer perceptron (MLP) technique.

Polymer Matrix Composite (PMC/Plastic Composite) often referred to as Plastic Composite with Natural fibre reinforcement has a huge interest in industries to manufacture components for various applications including medical, transportation, sports equipment etc. In the universe, different types of natural fibres are available which can be used for the reinforcement in PMC/Plastic Composite. So, the selection of appropriate fibre for the PMC/Plastic Composite/Plastic composite is a challenging task, but it can be done using an effective metaheuristic or optimization techniques. But in this type of optimal reinforcement fibre or matrix material selection, the optimization is formulated based on any one of the parameters of the composition. Hence to analyse the various parameter of any PMC/Plastic Composite/Plastic Composite without real manufacturing, a machine learning technique is recommended. The conventional simple or single-layer machine learning techniques were not sufficient to emulate the exact real-time performance of the PMC/Plastic Composite. Thus, a deep multi-layer perceptron (Deep MLP) algorithm is proposed to analyse the various parameter of PMC/Plastic Composite with natural fibre reinforcement. In the proposed technique the MLP is modified by including around 50 hidden layers to enhance its performance. In every hidden layer, the basis function is evaluated and subsequently, the sigmodal function-based activation is calculated. The proposed Deep MLP is utilized to evaluate the various parameters of PMC/Plastic Composite Tensile Strength, Tensile Modulus, Flexural Yield Strength, Flexural Yield Modulus, Young's Modulus, Elastic Modulus and Density. Then the obtained parameter is compared with the actual value and the performance of the proposed Deep MLP is evaluated based on the accuracy, precision, and recall. The proposed Deep MLP attained 87.2%, 87.18%, and 87.22% of accuracy, precision, and recall. Ultimately the proposed system proves that the proposed Deep MLP can perform better for the prediction of various parameters of PMC/Plastic Composite with natural fibre reinforcement.

Fabrication of Sustained Release System of Electrospun Poly(acrylic acid)/Dextran Nanofibers Using Emulsion Electrospinning as Wound Dressing Applications.

The burst release of drug is a problem associated with the use of common blending electrospinning. This problem can be avoided via fabrication of core-shell nanofibers where drug can be coated with polymer nanofibers as a shell. Moreover, there is a need to provide wound dressing with prolonged system of sustained release to accelerate the recovery of the wound. Currently, electrospun ciprofloxacin loaded poly(acrylic acid)/Dextran (Cipro@PAA/Dex) core-shell nanofibers can be prepared in green method using emulsion electrospinning. For comparison study, blend electrospun nanofibers (Cipro/PAA/Dex) was also prepared. The entrapment of drug into the polymeric material and the interaction between polymer blends were confirmed by FT-IR. Moreover, DSC was used to identify the type of interaction between polymeric chains. Field emission scanning electron microscope (FE-SEM) was used to study the nanofiber morphology and transmission electron microscope (TEM) and confocal laser scanning microscope (CLSM) were used to confirm the formation of core-shell structure. In vitro drug release profile was monitored by UV-Vis spectrophotometer and the results showed that Cipro@PAA/Dex exhibited controlled release behavior whereas Cipro/PAA/Dex showed burst release behavior. Moreover, the release mechanism is kinetically followed diffusion.

Cellulose gum and copper nanoparticles based hydrogel as antimicrobial agents against urinary tract infection (UTI) pathogens.

In the present study, stable copper nanoparticles (CuNPs) were successfully prepared in the hydrogel matrix. The prepared nanocomposite (HCuNPs) was characterized via x-ray diffraction (XRD), electron microscopy (TEM), and energy-dispersive (EDX) and x-ray photoelectron spectroscopic (XPS) studies. The wide scan XPS spectra support the presence of C, N and O in neat hydrogel; while, the XPS spectra of HCuNPs demonstrate the presence of Cu along with C, N, and O elements. TEM studies show the formation of spherical shaped CuNPs in the size range from 7 to 12nm. The rheology results reveal that the storage modulus (G') of the HCuNPs was found to be higher than the loss modulus (G"). Additionally, the antibacterial activities and cytotoxic were carried out against urinary tract infection (UTI) microbes and HeLa (cervical) cells respectively. The antibacterial results reveal that HCuNPs composites show higher zone of inhibition against these pathogens then that of corresponding hydrogel matrix. The cytotoxic effects suggest that the prepared nanocomposite could be used as promising candidates for biomedical applications.

Three-dimensional WS2 nanosheet networks for H2O2 produced for cell signaling.

Hydrogen peroxide (H2O2) is an important molecular messenger for cellular signal transduction. The capability of direct probing of H2O2 in complex biological systems can offer potential for elucidating its manifold roles in living systems. Here we report the fabrication of three-dimensional (3D) WS2 nanosheet networks with flower-like morphologies on a variety of conducting substrates. The semiconducting WS2 nanosheets with largely exposed edge sites on flexible carbon fibers enable abundant catalytically active sites, excellent charge transfer, and high permeability to chemicals and biomaterials. Thus, the 3D WS2-based nano-bio-interface exhibits a wide detection range, high sensitivity and rapid response time for H2O2, and is capable of visualizing endogenous H2O2 produced in living RAW 264.7 macrophage cells and neurons. First-principles calculations further demonstrate that the enhanced sensitivity of probing H2O2 is attributed to the efficient and spontaneous H2O2 adsorption on WS2 nanosheet edge sites. The combined features of 3D WS2 nanosheet networks suggest attractive new opportunities for exploring the physiological roles of reactive oxygen species like H2O2 in living systems.

Dispersion morphology and correlation to moduli using buckling metrology in clay-biopolymer nanocomposite thin films.

Structure-interaction-mechanical property correlation in bionanocomposite thin films is an area of growing interest for research and application areas from barrier to molecular transport to UV blocking layers for polymer solar cells to dielectric properties modification. Here we study flow coated ultrathin to thin films (70-150 nm) of clay bionanocomposites to understand the nanoparticle dispersion and its effect on nanomechanical properties. Binary and ternary thin film systems of polylactide (PLA), polycaprolactone (PCL), and Cloisite 30B (C30B) clay platelets were investigated. While C30B was only partially intercalated by PLA, it was almost completely intercalated by PCL due to strong hydrogen bonding. In addition, the dispersion of C30B improved continuously and linearly with increasing PCL content in homogeneously cast blended PLA:PCL. GIWAXS confirmed that the intercalated clay platelets in PLA and PCL were dominantly oriented parallel to the substrate. The method of strain induced elastic buckling instability for mechanical measurements (SIEBIMM) showed that pure PLA and PCL had in-plane modulus unchanged from bulk values for this range of ultrathin-thin films. In PLA/C30B nanocomposite thin films, the in-plane elastic modulus rapidly increased by up to 26% with 2 wt % C30B, but saturated thereafter up to 10 wt % C30B forming C30B aggregates. On the other hand, the in-plane elastic modulus of PCL/C30B thin films increased linearly by up to 43% with 10 wt % C30B due to the higher interaction driven dispersion, results that were shown to fit well with the Halpin-Tsai model. We conclude that the different strengthening behavior came from different interaction driven dispersion states of C30B in polymer matrices, governed by their molecular structures.