Polymer Sol Research Articles

A Polymer‐Sol Binder Realizes Single‐Particle Binding for Nacre‐Like Piezoelectric Nanocomposites and Component‐Integrated Batteries

AbstractAchieving precisely defined and stable component binding is of great interest for composite materials and batteries, but very challenging owing to the lack of effective strategies to manipulate the binder itself. Here, a concept of single‐particle binding (SPB) strategy is proposed based on a polymer‐sol binder to conquer the above challenge. To do that, a polymer‐sol binder is first prepared by dispersing commercial poly(vinylidene fluoride) (PVDF) powder into a mixture of its solvent and non‐solvent with a rational weight ratio of 8:2. Then, by manipulating this PVDF‐sol microfluid, PVDF particles are uniformly and singly introduced onto the surface of other components, such as graphene oxide nanosheets and battery separators. Results further show that the temperature‐induced sol–gel transition of the microfluid finally generates single‐particle fusion and strong component binding with commercial separators (31.6 N m−1). Meanwhile, a surface‐swelling model is proposed to understand its binding mechanism. Finally, this unique SPB strategy has been employed to fabricate nacre‐like nanocomposites with advanced self‐polarized piezoelectricity (23.0 mV N−1), and component‐integrated batteries with robust separator/electrode interphases. This SPB strategy with the PVDF‐sol binder may inspire significant studies on polymer sol, microfluidics, nanocomposites, battery interfaces and beyond.

Guiding Uniform Al Stripping with a Polymer Sol Electrolyte for Long-Lasting Al-Air Batteries

Guiding Uniform Al Stripping with a Polymer Sol Electrolyte for Long-Lasting Al-Air Batteries

Inorganic metal salts as additives in the design of cellulose/arabinogalactan hydrogels for prolonged delivery of simvastatin in simulated bio‐fluids

AbstractIn this study, carboxymethylcellulose and arabinogalactan were used to create an interpenetrating network (IPN) hydrogel system in the presence of AlCl3 alone or in combination with ZnSO4 salts. Ionotropic gelation caused the polymer sol droplets to transform into hydrogel particles in the presence of salts. The impact of salts on hydrogel properties was evaluated in terms of morphology, drug entrapment efficiency, swelling, and drug release kinetics. The cellulose IPN hydrogel particles containing 50% arabinogalactan looked spherical with evidence of surface folding when treated with AlCl3. Surface folding was reduced by an additional treatment with ZnSO4. Following treatment of the IPN particles with dual salts, a maximum drug entrapment efficiency of 88.77% was obtained. Surface erosion, as seen with aluminum‐IPN hydrogel particles, was minimized with the use of mixed salts as gelation medium. Furthermore, the use of mixed salts allowed the hydrogel particles to swell and consistently release simvastatin in simulated gastrointestinal fluids for up to 9 h. Thermal and x‐ray analyses revealed that the crystallinity of the drug reduced considerably after entrapment in the IPN hydrogel matrix. The infrared spectra analysis did not indicate any evidence of drug polymer interaction. The release of drug from the IPN hydrogel particles followed non‐Fickian diffusion mechanism. The dual metallic salts were found to be effective in creating physically stable cellulose‐arabinogalactan IPN hydrogel particles for sustained release of simvastatin in a varying pH environment of gastrointestinal tract.Highlights Dual inorganic salts allowed synthesis of cellulose/arabinogalactan hydrogel Additional use of ZnSO4 improved surface morphology of hydrogel particles Compatible environment of hydrogels allowed more than 88% drug entrapment Concentration of neutral arabinogalactan was crucial in dictating drug release Mixed salts controlled swelling and release of simvastatin from hydrogels

Calcium silicate‐reinforced pH‐sensitive alginate‐gellan gum composite hydrogels for prolonged drug delivery

AbstractThis study disclosed the synthesis and characterization of externally and/or internally crosslinked alginate‐gellan gum composite interpenetrating polymer networks (IPN) and IPN hydrogel microspheres for controlled delivery of gliclazid. The internal cross‐linking of the polymer sol was accomplished via slow release of Ca2+ ions from calcium silicate in presence of gluconic acid d‐lactone. The microspheres had spherical shape with smooth surface morphology. The IPN or composite IPN hydrogel microspheres had drug entrapment efficiency of 70%–76%. Incorporation of gellan gum or gellan gum/calcium silicate in the alginate sol sustained the release of drug in simulated gastrointestinal fluids over 12 h without any sign of particle disintegration. Inclusion of calcium silicate in alginate gels was ineffective in controlling drug release under simulated gastrointestinal milieu. The drug release obeyed anomalous diffusion mechanism after inclusion of gellan gum or gellan gum‐calcium silicate in the alginate gel microspheres. Fourier‐transform infrared (FTIR) spectroscopy and zeta analysis confirmed absence of drug‐polymer chemical interaction. The thermal and x‐ray diffraction analyses suggested that the drug transformed into amorphous state after incorporation into composite hydrogel system. Hence, it may be advantageous to combine internal and external gelation procedures for creating composite IPN or IPN hydrogel microspheres for avoiding burst effect of alginate microspheres and managing desired drug release patterns in vitro.

Controllable Preparation of Superparamagnetic Fe3O4@La(OH)3 Inorganic Polymer for Rapid Adsorption and Separation of Phosphate.

Superparamagnetic Fe3O4 particles have been synthesized by solvothermal method, and a layer of dense silica sol polymer is coated on the surface prepared by sol-gel technique; then La(OH)3 covered the surface of silica sol polymer in an irregular shape by controlled in situ growth technology. These magnetic materials are characterized by TEM, FT-IR, XRD, SEM, EDS and VSM; the results show that La(OH)3 nanoparticles have successfully modified on Fe3O4 surface. The prepared Fe3O4@La(OH)3 inorganic polymer has been used as adsorbent to remove phosphate efficiently. The effects of solution pH, adsorbent dosage and co-existing ions on phosphate removal are investigated. Moreover, the adsorption kinetic equation and isothermal model are used to describe the adsorption performance of Fe3O4@La(OH)3. It was observed that Fe3O4@La(OH)3 exhibits a fast equilibrium time of 20 min, high phosphate removal rate (>95.7%), high sorption capacity of 63.72 mgP/g, excellent selectivity for phosphate in the presence of competing ions, under the conditions of phosphate concentration 30 mgP/L, pH = 7, adsorbent dose 0.6 g/L and room temperature. The phosphate adsorption process by Fe3O4@La(OH)3 is best described by the pseudo-second-order equation and Langmuir isotherm model. Furthermore, the real samples and reusability experiment indicate that Fe3O4@La(OH)3 could be regenerated after desorption, and 92.78% phosphate removing remained after five cycles. Therefore, La(OH)3 nanoparticles deposited on the surface of monodisperse Fe3O4 microspheres have been synthesized for the first time by a controlled in-situ growth method. Experiments have proved that Fe3O4@La(OH)3 particles with fast separability, large adsorption capacity and easy reusability can be used as a promising material in the treatment of phosphate wastewater or organic pollutants containing phosphoric acid functional group.

Stable Amorphous Solid Dispersion of Eplerenone Prepared with Water Soluble Polymer by Spray Drying Technique

Class II in the Biopharmaceutical Classification System, eplerenone (EPL) is a selective aldosterone antagonist. Due to its poor solubility, EPL has limited bioavailability. Here, an innovative spray-drying method was used to transform a water soluble polymer into an amorphous dispersion of the EPL. Different polymer SOL/EPL ratios were tested to determine EPL’s solubility and dissolution enhancement properties. In order to learn more about the physical and chemical properties of this novel amorphous solid dispersion (ASD), methods like powder X-ray diffraction spectroscopy (PXRD), differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FTIR), particle size distribution (PSD) using a Malvern instrument, and scanning electron microscopy (SEM) were used. There was no chemical interaction between the binary mixture of EPL and SOL which was confirmed from the FTIR spectra obtained. The enhancement in the solubility and dissolution of EPL and binary mixture prepared were due to the amorphous conversion of EPL in the SOL polymer (amorphous solid dispersion), which was confirmed from DSC thermogram, PXRD spectra obtained and was also confirmed from the solubility study, in-vitro dissolution study. Finally, ex-vivo intestinal absorption study performed on the goat intestine using amorphous solid dispersion and pure EPL, also improved intestinal absorption of EPL through amorphous solid dispersion prepared.

Fabrication and amplified spontaneous emission behavior of FAPbBr3 perovskite quantum dots in solid polymer rods

Abstract Formamidinium lead tribromide (FAPbBr3) perovskite quantum dot (PQ-Dot) solution was incorporated in a polymer sol, which was used to fabricate solid nanocomposite rods and disks. The solid nanocomposite samples were studied by different characterization techniques. The absorption, emission, and excitation spectra of the PQ-Dot in the solid rods/disks were quite significant as compared to the spectra of the PQ-Dot solution. Scanning electron microscopy (SEM) was used to inspect the structural morphology of the PQ-Dot in the solid environment. The PQ-Dot particles were evidently present in the solid matrix and were confirmed by the SEM images and energy dispersive X-ray spectroscopy (EDX) spectra. The size of the PQ-Dots was examined by transmission electron microscopy (TEM). The majority of the particles were about 3–8 nm in size. The spontaneous and stimulated emission profiles of the solid composite rods/disks were studied using pumping energy ranging from 2 μJ to 18 μJ from a high-power picosecond neodymium-doped yttrium aluminum garnet (Nd:YAG) tunable laser system. The observed emission signal was quite significant. The emission peak of the PQ-Dot solution had a slight change when it was included in the solid matrix. Amplified spontaneous emission (ASE) behavior was obtained from the PQ-Dot composite rod. The ASE peaks were quite steady at different levels of excitation energy. ASE was achieved at low threshold energy. The composite rod with ASE behavior indicates that it is a promising composite material that can be used to achieve lasing in the future. The ASE obtained from the composite rods/disks may improve to achieve lasing if a high concentration of PQ-Dot solution is used in the matrix.

Deposition of Hybrid Photocatalytic Layers for Air Purification Using Commercial TiO2 Powders.

Photocatalytic nanomaterials, using only light as the source of excitation, have been developed for the breakdown of volatile organic compounds (VOCs) in air for a long time. It is a tough challenge to immobilize these powder photocatalysts and prevent their entrainment with the gas stream. Conventional methods for making stable films typically require expensive deposition equipment and only allow the deposition of very thin layers with limited photocatalytic performance. The present work presents an alternative approach, using the combination of commercially available photocatalytic nanopowders and a polymer or inorganic sol–gel-based matrix. Analysis of the photocatalytic degradation of ethanol was studied for these layers on metallic substrates, proving a difference in photocatalytic activity for different types of stable layers. The sol–gel-based layers showed an improved photocatalytic activity of the nanomaterials compared with the polymer layers. In addition, the used preparation methods require only a limited amount of photocatalyst, little equipment, and allow easy upscaling.

Fractal-Percolation Structure Architectonics in Sol-Gel Synthesis.

It was developed a new technique to assess micro- and mesopores with sizes below a few nanometers. The porous materials with hierarchical fractal-percolation structure were obtained with the sol-gel method. The tetraethoxysilane hydrolysis and polycondensation reactions were performed in the presence of salts as the sources of metal oxides. The porous materials were obtained under spinodal decomposition conditions during application of the polymer sol to the substrate surface and thermal treatment of the structures. The model is based on an enhanced Kepler net of the 4612 type with hexagonal cells filled with a quasi-two-dimensional projection of the Jullien fractal after the 2nd iteration. The materials obtained with the sol-gel method were studied using the atomic force microscopy, electron microscopy, thermal desorption, as well as an AutoCAD 2022 computer simulation of the percolation transition in a two-component system using the proposed multimodal model. Based on the results obtained, a new method was suggested to assess micro- and mesopores with sizes below a few nanometrs, which cannot be analyzed using the atomic force microscopy and electron microscopy.

A selective organosilica membrane for ethyl acetate dehydration by pervaporation

AbstractOrganosilica bis(triethoxysilyl) ethane (BTESE) membranes were explored for pervaporation dehydration of binary and ternary mixtures of ethyl acetate (EA) by undiluted sol coating combined with flash firing. Three BTESE membranes (M1, M2, and M3) were fabricated on macroporous supports by varying BTESE concentrations (0.5, 2.5, and 5 wt% BTESE, respectively) in polymer sols. The membranes were characterized by DLS, SEM, FTIR, XRD, contact angle, AFM, and pervaporation performance to discuss the effect of the BTESE contents in the polymer sol on the formation and dehydration performance of resulting organosilica membranes. It was found that 5 wt% loading of BTESE led to a highly selective membrane for dehydration of EA/H2O mixture. Among the synthesized membranes, M3 delivered flux of 0.84 ± 0.05 kg.m−2.h−1 with a selectivity of >10,000 for EA/H2O mixture (98/2 wt%) at 60°C. The time course of pervaporation dehydration for the EA/H2O mixture (95/5 wt%) confirms the stability of BTESE membrane in the investigated time period of 120 h. Further, the membrane exhibited excellent selectivity larger than 10,000 for separation of ternary mixtures (90/2/8 wt%) of ethyl acetate/ethanol/water and n‐propyl acetate/isopropanol/water respectively, the composition of which is similar to the top product of the distillation column used in the industrial esterification process. The best separation performance and excellent acid stability of BTESE membranes in this study suggest that the simple synthesis protocol of undiluted sol coating and flash firing will provide a cost‐effective, quick, and efficient synthesis route for practical membrane based applications.

Nanoparticles of La1-xSrxMnO3 (0.23 ≤ x ≤ 0.25) manganite: Features of synthesis and crystallochemical properties

Nanoparticles of lanthanum-strontium manganite were synthesized via sol-gel method. It was investigated that La1-xSrxMnO3 (0.23 ≤ x ≤ 0.25) precursors were formed by complexing reactions during the synthesis and pyrolysis of polymer sol. X-ray diffraction data showed that single-phase crystalline nanoparticles began to form in one-stage at 600 °C; the level of crystallinity increased with the growth of the treatment temperature. It was shown that the heat treatment effected on the morphology of the particles. Magnetic fluids based on La1-xSrxMnO3 (0.23 ≤ x ≤ 0.25) nanoparticles were prepared and it was shown that heating efficiency of magnetic fluids in an alternating magnetic field strongly depended on their crystallochemical properties. It was established that La1-xSrxMnO3 (0.23 ≤ x ≤ 0.25) nanoparticles obtained at 800 °C had optimal crystallochemical properties and morphology, possessed high heating efficiency in an alternating magnetic field and are expected to be promising for investigations as the inducers in magnetic hyperthermia.

In situ decoration of plasmonic silver nanoparticles on poly(vinylidene fluoride) membrane for versatile SERS detection

A new strategy based on a polymer sol was proposed for the in situ fabrication of a poly(vinylidene fluoride) (PVDF) membrane decorated with silver nanoparticles (AgNPs) for application in surface enhanced Raman scattering (SERS).

Thin-walled building structures with improved properties for high-rise construction

A high-efficient complex reactive composition consisting of a polycarboxylate polymer, cesium nitrate (CsNO3) and silica sol was developed for cast-in-place housing construction from high-strength concrete. The use of this composition provides production of high-strength concrete with increased crack resistance.

Supercapacitor Electrode from Electrospray of Polymeric Sol As Carbon Precursor on Current Collector

This presentation describes a process, involving electrospray of carbonaceous polymer sol on a current collector-substrate, followed by in situ curing, drying and carbonization. The electrospray process splits the precursor sol into fine droplets by Coulombic fission, prior to the deposition on the substrate. The pyrolysis of cured and dried gel film provides the active layer with enhanced internal surface area for the double layer capacitance, and lower resistance to charge transport. The choices of different methods and parameters e.g., sol composition, electrospray voltage, drying method, pyrolysis and pore activation protocols make possible the tuning of pore structure. The carbonaceous precursor sol, considered in this work is resorcinol formaldehyde (RF). The sol-gel transition involves addition and polycondensation reactions respectively, where the latter step contributes to crosslinks. Upon pyrolysis, the crosslinks develop into micropores. RF gel can be prepared in either aqueous or organic solvent, and the choice of solvent may affect the morphology of the deposited film. Further, the method of solvent removal for the drying of cured RF gel film contributes to the mesopore formation in the carbon film. In particular, the simultaneous evaporation of organic solvent at the time of curing vis-à-vis the lyophilization of aqueous gel film can lead to distinctly different pore structure. The hierarchical structure with connected mesopores enables better access to the micropores. The presentation addresses these aspects using experimental measurements. The nitrogen adsorption-desorption experiment on bulk carbon powder showed the pore size distribution and specific surface area. The carbon powder is also analyzed here using XRD, FTIR, and Raman spectroscopy. Carbon paper is used in this work as the current collector. Sufficient adhesion between the deposited film and the carbon paper enabled handling of the composite through curing, solvent removal, and carbonization steps without peel. The morphology of the film is studied under SEM, and the pore size is calculated using the image analysis software. The electrochemical performance of the electrode is studied in a symmetric cell using KCl and KOH respectively as electrolytes. The cyclic voltammetry, chronopotentiometry, and impedance spectroscopy are performed to estimate specific capacitance, electrolyte resistance at different extents of ion penetration into the pore. The retention of capacitance and coulombic efficiency after several charge-discharge cycles are reported here.

Facile in situ formation of hybrid gels for direct-forming tissue engineering

Development of bioactive hydrogel as extracellular matrix (ECM) is a very important field for cell-based therapy. In this study, we provided a facile method based on sol-gel process for fabricating bioactive composite hydrogels. The composite hydrogels were composed of sol-gel derived silica and biopolymer. Different amounts of silica solution (20–80wt%) were mixed with 2% polymer sol (alginate) followed by aging and gelation to form a network so that the alginate-silica hybrid mixture could form a gel without any additional crosslinking process. The self-gelation time of the hybrid hydrogel measured by rheometer was reduced as the content of silica was increased. Such hydrogels had highly porous and interconnected structures. Their strut showed uniform surface texture. Under physiological conditions (PBS, 37°C), these hybrid hydrogels exhibited long-term stability compared to alginate hydrogels as control. The mechanical properties of these hydrogels such as compressive strength, compressive modulus, and work of fracture were significantly enhanced by hybridization with sol-gel derived silica. In vitro cell tests revealed that these hybrid hydrogels exhibited improved cell adhesion and proliferation behaviors compared to pure alginate hydrogel cross-linked by CaCl2 solution. Furthermore, cell encapsulation within these hydrogels revealed that their alginate-silica composite provided suitable microenvironment for cell survival.

Porous Boron Carbon Nitride Nanosheets as Efficient Metal-Free Catalysts for the Oxygen Reduction Reaction in Both Alkaline and Acidic Solutions

Carbon materials have become a hot topic as potential substitutes for Pt/C catalysts for the oxygen reduction reaction (ORR). However, most of them exhibit their catalytic activities only in alkaline solutions, which severely limits their application in polyelectrolyte membrane fuel cells. To address this issue, here porous boron carbon nitride (BCN) nanosheets are fabricated by a facile and efficient polymer sol–gel method, which involves the annealing of polyvinylic akohol (PVA), boric acid, guanidine, and poly(ethylene oxide-co-propylene oxide) (P123) gel mixtures. The as-prepared porous BCN nanosheets possess a high surface area of 817 m2/g and display impressive ORR catalytic performance in both alkaline and acidic media, rivalling that of commercial Pt/C and other recently reported carbon materials. Importantly, the resulting metal-free catalysts exhibit much greater durability and higher methanol tolerance in both alkaline and acidic environments. This study provides a new insight into metal-free ORR catalysts that are practicable in industrial fuel cells.

Structuring polymer gels via catalytic reactions.

We use computer simulations to investigate how a catalytic reaction in a polymer sol can induce the formation of a polymer gel. To this aim we consider a solution of homopolymers in which freely-diffusing catalysts convert the originally repulsive A monomers into attractive B ones. We find that at low temperatures this reaction transforms the polymer solution into a physical gel that has a remarkably regular mesostructure in the form of a cluster phase, absent in the usual homopolymer gels obtained by a quench in temperature. We investigate how this microstructuring depends on catalyst concentration, temperature, and polymer density and show that the dynamics for its formation can be understood in a semi-quantitative manner using the interaction potentials between the particles as input. The structuring of the copolymers and the AB sequences resulting from the reactions can be discussed in the context of the phase behaviour of correlated random copolymers. The location of the spinodal line as found in our simulations is consistent with analytical predictions. Finally, we show that the observed structuring depends not only on the chemical distribution of the A and B monomers but also on the mode of formation of this distribution.

Composite coating composed of zeolite Y (FAU) and binder prepared from bis(triethoxysilyl)ethane

Composite coatings were prepared from dealuminated zeolite Y and a hybrid polymer sol made from bis(triethoxysilyl)ethane. The zeolite pore accessibility and the microstructure were determined by gas sorption experiments and SEM measurements. The influence of different zeolite loadings was analyzed. In conclusion, the samples offered good pore accessibility if the zeolite content was at least 60% by weight. Such samples exhibited secondary pores in the macropore dimension. Furthermore, the obtained coatings offered wipe resistance and could easily be applied on flexible substrates. In addition, they showed reversible adsorption capacity of formaldehyde, which demonstrates their potential for application as an adsorptive layer for pollutants.

A novel electrochemical sensor for selective determination of uranyl ion based on imprinted polymer sol–gel modified carbon paste electrode

In this work, an electrochemical sensor by combining sol–gel processing and paste electrode was developed. Functional precursor was first synthesized and reacted with tetramethoxysilane to obtain polymer sol–gel and then used as a receptor for selective binding and sensing of uranyl ion in aqueous solution. Ion-imprinted polymer sol–gel synthesized in the presence of uranyl ion was characterized by Fourier transform-infrared spectroscopy, scanning electron microscopy and N2 adsorption–desorption analysis by comparing with non-imprinted sol–gel obtained in the absence of uranyl ion. Surface area, pore volume and diameter were analyzed from the profile of nitrogen adsorption. Uranyl ion imprinted network was employed to achieve a suitable conformation for electrochemical reduction of uranyl ion and also to improve the selectivity of the sensor. The results showed that the ion imprinted polymer sol–gel modified carbon paste electrode exhibited selectivity toward uranyl ion compared to electrode containing non-imprinted polymer sol–gel. The ion-imprinted sensor was also successfully employed to detect uranyl ion in real samples and exhibited distinctive change in current upon interaction with uranyl ion. The corresponding selectivity factors of the sensor toward uranyl ion against the other analogues were evaluated.

Synthesis of high porous electrospun hollow TiO2 nanofibers for bone tissue engineering application

Highly porous, hollow TiO2 nanofibers (NFs) were fabricated through coaxial nozzle electrospinning using a polymer sol–gel solution of CaCO3 and TiO2 precursor. Hollow and porous TiO2 NFs were obtained by etching CaCO3 on calcined TiO2 fibers using dilute HCl. Characterization of the as-synthesized materials were performed using FE-SEM and XRD before and after 24h of bio-mineralization. The in vitro cell culture test was performed using MC3T3-E1 osteoblast cells to assess cell response of the different NFs. The results suggested that as-synthesized porous nanotubes have better biocompatibility for bone regeneration and implantations compared to other nonporous TiO2 nanorods or NFs.