Development of functional graphene oxide-urethane coating systems from Ricinus communis seed oil

The surface-modified graphene oxide (GO) nanoparticles and their blending with a fixed percentage of trimethylopropane (TMP) in Ricinus communis seed oil were successfully prepared in a one-pot urethane reaction using 4,4′-diisocyanato dicyclohexylmethane (H12MDI) and methyl isobutyl ketone (MIBK) as the reaction solvent. The structural elucidation and surface morphology of pristine and hybrid composites of the polyurethane coating films were investigated with the aid of Fourier transform infrared spectroscopy (FT-IR), Energy-dispersive X-ray spectroscopy (EDX), Proton nuclear magnetic resonance (1H NMR), X-ray diffraction (XRD), and Scanning electron microscope (SEM). The presence of FT-IR absorption peaks at 790 cm−1 to 870 cm−1, 990 cm−1, and 1017 cm−1 confirms the following functional groups phenyl -CH bend, stretching phenolic -CO, and epoxyl -C-O-C, respectively in modified graphene oxide. An evaluation of the thermal stability of the coating films that were synthesised was carried out with the use of a thermogravimetric analyzer (TGA). It was seen that as the amount of modified graphene oxide in the urethane films increased, so did the water contact angle from 0% to 0.5%. Antimicrobial and anticorrosive properties of the materials were also evaluated

Quasi-Solid Semi-Interpenetrating Polymer Networks as Electrolytes: Part III. Probing the Mechanism of Ionic Charge Transport Employing Temperature-Step Electrochemical Impedance Spectroscopy

The correlated ion-transport mechanism and its dependence on microscopic phase separation for a new class of quasi-solid semi-IPN electrolytes is probed in considerable detail using temperature-step electrochemical impedance spectroscopy. The response of electrolyte matrices under alternating current perturbation is comprehensively analyzed using a simulated model fit to extract pertinent information relevant to the phase composition and homogeneity, contribution of each phase, interfacial charge-transfer resistance, phase entanglement zones, bulk relaxation time for ionic hopping mechanisms, coupled segmental motions, rate of site reorganization that dictates successful hopping events, and estimates of ionic transport numbers. The normalized complex plane Nyquist plots (ρ′ versus ρ″) show two well-defined regions for bulk (in mid- and high-frequency regions) and electrode–electrolyte interfacial impedance (in low-frequency regions). Rigorous analysis indicates the presence of three microscopic phases in the matrix bulk (pure poly­(ethylene oxide)–polyurethane (PEO-PU), pure poly­(ethylene glycol) dimethyl ether (PEGDME), and PEO-PU/PEGDME mixed phase) along with the charge-transfer resistance (<i>R</i>_ct) which contribute to the bulk resistance. Spectroscopic plots of complex impedance against frequency (<i>Z</i>″ versus log <i>f</i>) depict Debye peaks, providing an estimate of the bulk relaxation time (τ_peak). Profiles depicting the real component of conductivity (σ′(ω)) as a function of frequency (log <i>f</i>) follow a modified universal power law where the simulated fit results reveal vital information on the site relaxation rates, cumulative favorability for successful hopping events, and predominant charge carrier type. The behavior of the dielectric contributions provides insights into the various ion polarization processes dominant in the high-, mid-, and low-frequency windows of the sweep. These trends were further correlated with our prior evaluation of the <i>physico-chemical</i> properties of the semi-IPN matrices to propose a rational physical model for these complex systems

Quasi-Solid Semi-Interpenetrating Polymer Networks as Electrolytes: Part II. Assessing the Modes of Ion–Ion and Ion–Polymer Interactions Employing Mid-Fourier Transform Infrared Vibrational Spectroscopy

The present study is a detailed vibrational spectroscopy investigation on the ion–ion and ion–polymer interactions that exist post-solvation or complexation in a new class of quasi-solid polymer electrolytes. Fourier transformed infrared spectra of the synthesized semi-interpenetrating polymer networks (semi-IPNs) matrix of poly­(ethylene-oxide)-poly­urethane/­poly­(ethylene glycol) di­methyl ether (P4K-PU/P2 (30:70)) complexed with LiCF₃SO₃ and LiN­(CF₃SO₂)₂ is deconvoluted for three primary stretching zones (ether, carbonyl, and amine) to isolate and identify the ionic species and polymer segments involved. The analysis revealed crucial information pertaining to the localized ion-association behavior, vital clues regarding the competitive interactions present, and important insights into the mechanisms of charge transport. The spectroscopic signatures imply favorable presence of positively charged triple ions or higher aggregate species along with a significant amount of “free” ions and a preferential solubility of the added electrolytes in the amorphous domains of the polymer. Critical salt concentrations <i>C</i>_c of EO/Li = 20 and EO/Li = 30 estimated for the LiTf and LiTFSI systems, respectively, are in good agreement with experimentally observed conductivity results. The appreciably high ionic conductivity in these semi-IPN systems could be effectively rationalized considering the nature of ionic dissociation, reassociation, and competitive interaction mechanisms. The availability of a highly disordered matrix with an optimal number of free sites, excellent segmental mobility, appreciable free volume, and finally the existence of adequate labile ionic species, all aids in the high charge transport observed in this new class of quasi-solid electrolytes

Data on bone marrow stem cells delivery using porous polymer scaffold

Low bioavailability and/or survival at the injury site of transplanted stem cells necessitate its delivery using a biocompatible, biodegradable cell delivery vehicle. In this dataset, we report the application of a porous biocompatible, biodegradable polymer network that successfully delivers bone marrow stem cells (BMSCs) at the wound site of a murine excisional splint wound model. In this data article, we are providing the additional data of the reference article “Porous polymer scaffold for on-site delivery of stem cells – protects from oxidative stress and potentiates wound tissue repair” (Ramasatyaveni et al., 2016) [1]. This data consists of the characterization of bone marrow stem cells (BMSCs) showing the pluripotency and stem cell-specific surface markers. Image analysis of the cellular penetration into PEG–PU polymer network and the mechanism via enzymatic activation of MMP-2 and MMP-13 are reported. In addition, we provide a comparison of various routes of transplantation-mediated BMSCs engraftment in the murine model using bone marrow transplantation chimeras. Furthermore, we included in this dataset the engraftment of BMSCs expressing Sca-1+Lin−CD133+CD90.2+ in post-surgery day 10

Viable Method for the Synthesis of Biphasic TiO₂ Nanocrystals with Tunable Phase Composition and Enabled Visible-Light Photocatalytic Performance

Here we demonstrate a facile method to synthesize high-surface-area TiO₂ nanoparticles in aqueous-ethanol system with tunable brookite/rutile and brookite/anatase ratio possessing high surface area that exhibits enhanced photoactivity. Titanium tetrachloride (TiCl₄) is used as the metal precursor of choice and the tuning of phase compositions are achieved by varying the water:ethanol ratio, used as mixed solvent system. The synthesized samples were characterized in detail using X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), BET nitrogen sorption measurements, and UV–vis diffuse reflectance spectroscopy (UV-DRS). The photocatalytic activity of biphasic TiO₂ nanocrystals was evaluated by following the degradation kinetics of rhodamine-B dye in aqueous solution and under visible light. Mixed-phase TiO₂ nanostructures composing 83% brookite and 17% of rutile exhibited superior photoactivity when compared to Degussa P25 and phase-pure anatase nanocrystals. The exceptional photocatalytic activity of the synthesized nanostructures can be elucidated on the account of their large surface area and biphasic composition. On the basis of the detailed investigation reported herein, we conclude that tuning the ethanol volume in the mixed-solvent reaction system holds the key to tailor and control the final TiO₂ phase obtained

Mesoporous Assembly of Cuboid Anatase Nanocrystals into Hollow Spheres: Realizing Enhanced Photoactivity of High Energy {001} Facets

Herein, we showcase a unique one-step synthetic strategy to obtain a mesoporous assembly of cuboid anatase nanocrystals into hollow spheres that not only offers high surface area but also predominantly tenders the reactive high energy {001} facets. The detailed experimental studies, parameter optimization, and characterizations reveal the crucial role played by the shape and structure directing agents during nucleation and growth. Concentration of F^–-ions plays a determining role in stabilizing the size and shape at the initial stage of formation while an optimal balance of SO₄^2– anions is critical in generating the hollow porous assemblies while retaining the morphology of the primary nanocuboid subunits. The single crystalline anatase TiO₂ nanocuboids and their hollow spherical assemblies; both show substantial enhancement in photocatalytic and photoelectrochemical activity when compared with commercial P25. Photoelectrodes fabricated using cuboid nanocrystals demonstrate a superior DSSC efficiency when compared to Degussa P25. In combination with the mesoporous hollow spherical assemblies of nanocuboids as an overlayer, the power conversion efficiency of these photoelectrodes considerably increased owing to enhanced light harvesting. A confluence of <i>physicochemical</i> parameters, <i>i.e</i>, high surface area, reactive {001} facets, high dye-loading capacities, enhanced light scattering and confinement, low electron transfer resistance, and improved electrode–electrolyte interface, all positively impact the overall photoconversion efficiency. To exemplify the photocatalytic performance of the synthesized nanocuboids, oxidation of terephthalic acid was studied as a model system. A significantly superior photocatalytic activity mediated by ^•OH radicals draws strong support from the high photocurrents observed for these mesoporous hollow architectures

Hierarchical In(OH)₃ as a Precursor to Mesoporous In₂O₃ Nanocubes: A Facile Synthesis Route, Mechanism of Self-Assembly, and Enhanced Sensing Response toward Hydrogen

Mesoporous In₂O₃ nanocubes were achieved in this present work following a transformation from hierarchical structures of mesoporous In­(OH)₃ nanocubes synthesized hydrothermally. Appreciable control on the morphology of In­(OH)₃ nanostructures was attained by optimizing the reactant concentration, ratio of structure directing agent in the reaction medium (water/PEG ratio), the reaction temperature, and time. The synthesized samples were characterized extensively by XRD, TG-DTA, micro-Raman, and UV-DRS. Surface area and pore size distribution were determined from N₂ adsorption and desorption isotherms. Morphological evaluations carried out using electron microscopy in scanning (FE-SEM) and transmission (TEM) mode not only provided information on the size and shape of the materials but also revealed the hierarchical assembly consisting of primary and secondary structures. Controlled studies as a function of various reaction parameters and the morphological evolution observed are rationally correlated to propose a plausible formation mechanism. Further, hydrogen gas sensing properties (sensitivity, sensor response, and recovery time) of the as-prepared In₂O₃ nanostructures (nanocubes, nanobricks, nanoflakes, and nanoparticles) were investigated to demonstrate the influence of morphology. Owing to the porous structures and large surface area, In₂O₃ nanocubes exhibit superior sensitivity with short response/recovery times at concentrations as low as 100 ppb. Surface decoration with Pd nanoparticles activates these nanocubes, promoting excellent sensing response and selectivity toward hydrogen at room temperature

Hierarchical Mesoporous In₂O₃ with Enhanced CO Sensing and Photocatalytic Performance: Distinct Morphologies of In(OH)₃ via Self Assembly Coupled in Situ Solid–Solid Transformation

The present investigation details our interesting findings and insights into the evolution of exotic hierarchical superstructures of In­(OH)₃ under solvothermal conditions. Controlled variation of reaction parameters such as, reactant concentration, solvent system, crystal structure modifiers, water content along with temperature and time, yielded remarkable architectures. Diverse morphologies achieved for the first time includes (i) raspberry-like hollow spheres, (ii) nanosheet-assembled spheres, (iii) nanoparticle-assembled spheres, (iv) nanocube-assembled hollow spheres, (v) yolk-like spheres, (vi) solid spheres, (vii) nanosheets/flakes, and (viii) ultrafine nanosheets. A plausible mechanism is proposed based on the evidence gathered from a comprehensive analysis aided by electron microscopy and X-ray diffraction studies. Key stages of morphological evolution could be discerned and rationally correlated with nucleation, growth, oriented attachment, and Ostwald ripening mediated by dissolution-redeposition mechanism coupled with solid evacuation. Remarkably phase-pure <i>bcc</i>-In₂O₃ with retention of precursor morphology could be realized postcalcination at 400 °C, which underlines the advantage of this strategy. Two typical hierarchical structures (raspberry-like hollow spheres and nanoparticles assembled spheres) were investigated for their gas sensing and photocatalytic performances to highlight the advantages offered by nanostructuring. An impressive sensor response, <i>S</i>_max ≈ 7340 and 4055, respectively for the two structures along with appreciably fast response/recovery times over a wide concentration range and as low as 1 ppm exhibits the superior sensitivity toward carbon monoxide (CO). When compared to commercial In₂O₃, estimated rate constant indicates ∼3–4 times enhancement in photocatalytic activity of the substrates toward Rhodamine-B