Pratyay Basak

Thermo‐mechanical Properties of PEO‐PU/PAN Semi‐Interpenetrating Polymer Networks and their LiClO4 Salt‐Complexes

This paper is an investigation on the thermo‐mechanical properties of a new class of materials, which holds promise for its potential use as solid polymer electrolytes, i.e., SPE material. A series of poly(ethylene oxide)‐polyurethane/poly(acrylonitrile) (PEO‐PU/PAN) semi‐IPNs, along with their LiClO4 salt complexes, were characterized for their thermal, mechanical and dimensional stability using DSC, TG‐DTA, UTM and DMTA. The glass transition temperature (Tg) of both the undoped and doped semi‐IPNs, obtained by DSC, remained well below room temperature (∼−50°C to −35°C), satisfying one of the essential requirements to serve as a SPE host matrix. The crystallization process in the PEO segments of the PEO‐PU/PAN semi‐IPNs was prevented at higher salt concentrations, which is attributed to the Li+ ion mediated pseudo‐crosslinks. Good thermal stability of the semi‐IPNs was evident from the degradation onset temperature (T0∼240°C) with a three‐stage degradation process, which is independent of the PAN content as observed from differential thermogravimetric studies. The incorporation of PAN in the PEO‐PU networks results in improved mechanical properties, such as tensile strength and modulus while retaining the flexibility of the semi‐IPNs. The peak temperatures and storage modulus obtained from DMTA correlates well with the observations of DSC and tensile measurements. †IICT Communication No.: 0407019.

1,4-Dihydropyrrolo[3,2-b]pyrroles as a Single Component Photoactive Layer: A New Paradigm for Broadband Detection

Single component organic photodetectors capable of broadband light sensing represent a paradigm shift for designing flexible and inexpensive optoelectronic devices. The present study demonstrates the application of a new quadrupolar 1,4-dihydropyrrolo[3,2-b]pyrrole derivative with spectral sensitivity across 350-830 nm as a potential broadband organic photodetector (OPD) material. The amphoteric redox characteristics evinced from the electrochemical studies are exploited to conceptualize a single component OPD with ITO and Al as active electrodes. The photodiode showed impressive broadband photoresponse to monochromatic light sources of 365, 470, 525, 589, 623, and 830 nm. Current density-voltage (J-V) and transient photoresponse studies showed stable and reproducible performance under continuous on/off modulations. The devices operating in reverse bias at 6 V displayed broad spectral responsivity (R) and very good detectivity (D*) peaking a maximum 0.9 mA W-1 and 1.9 × 1010 Jones (at 623 nm and 500 μW cm-2) with a fast rise and decay times of 75 and 140 ms, respectively. Low dark current densities ranging from 1.8 × 10-10 Acm-2 at 1 V to 7.2 × 10-9 A cm-2 at 6 V renders an operating range to amplify the photocurrent signal, spectral responsivity, and detectivity. Interestingly, the fabricated OPDs display a self-operational mode which is rarely reported for single component organic systems.

Functional polyurethane–urea coatings from sulfur rich hyperbranched polymers and an evaluation of their anticorrosion and optical properties

The study showcases functional polyurethane–urea coatings from sulfur rich hyperbranched polyols. A multistep synthetic route was used that can be easily adopted as a one pot approach towards generating (i) new monomers, (ii) hyperbranched macromonomers, (iii) reactive pre-polymers and (iv) functional polymeric architectures with exotic properties. Thiol–yne click chemistry was successfully employed to synthesize a trihydroxy terminated sulfur-core monomer (B3), which was reacted with succinic anhydride to achieve an acid terminated monomer, A3. Following an A3 + B3 approach, these complementary pairs led to the formation of a generation-1 sulfur rich hyperbranched polyol. Achieving higher generation via repetitive steps is demonstrated with the formation of generation-2 polyols. The targeted monomers, intermediates and polyols were confirmed using 1H-NMR, 13C-NMR, ESI-MS/MALDI-ToF, and mid-FTIR techniques. The degree of branching, ∼86.4 and 84.4% for the generation 1 and 2 hyperbranched polyols respectively, indicated highly branched systems. The rheology data from these hyperbranched polyols established their suitability for processing and application development. Isocyanate terminated prepolymers were derived from these polyols through reaction with a diisocyanate, and, when moisture cured, yielded high quality polyurethane–urea films/coatings. Comprehensive evaluation of the morphologies using FE-SEM, and thermo-mechanical and optical properties (refractive index 1.5, %T > 90) revealed the interesting features of the coatings. Moreover, a salt spray (more than 1500 hours of stability) and electrochemical tests (corrosion rates 4.2 × 10−4 and 6.3 × 10−4 mm per year) of the developed coatings emphasized their excellence in protecting against corrosion. Additionally, these additive-free films displayed significant inhibition towards microbes.

Nanostructured Metal Oxides: Low Temperature Synthesis and Biomimetic Approaches

The last few decades have seen tremendous explosion of activity in the area of Nanoscience and Nanotechnology. Semiconducting metal oxides and their composites form an important class of materials for the envisaged cutting edge applications. Several approaches have been attempted by researchers to prepare nanocrystalline metal oxides, study the material properties and explore their feasibility for a variety of applications. In this review, the highlights of authors’ research efforts vis-à-vis the global state of nanomaterial research is discussed briefly. A comprehensive outlook on some of the important metal oxides, the various strategies practiced to synthesize them, along with a bird’s eye view of the results, important breakthroughs and achievements in the last decade are briefly discussed.

Swapping conventional salts with an entrapped lithiated anionic polymer: fast single-ion conduction and electrolyte feasibility in LiFePO4/Li batteries

Herein, we report on a new class of quasi-solid polymer electrolyte matrix that supports appreciably fast single-ion conduction. Showcased as the first example of tailoring a lithiated anionic polymer employing semi-interpenetrating polymer networks approach, the study probes several key factors, such as, (i) polymer–polymer/ion–polymer interactions (ii) phase homogeneity, (iii) effect of oligomeric plasticization, (iv) transition temperatures and thermostability, and (v) H-bonding and degree of crystallinity for a series of binary and ternary compositions, and determines their effect on the overall electrochemical properties. Employing a mutually exclusive reaction strategy, lithiated poly(3-sulfopropyl methacrylate) was synthesized via free-radical polymerization and interpenetrated into a growing polyether-polyurethane network to achieve solid free-standing films. Quantitative cation exchange, polymerization and network incorporation are confirmed by 1H-, 13C-NMR, XRD, ICP-OES, ESI-MS, MALDI-TOF and mid-FTIR. Comprehensive evaluations of physicochemical and electrochemical properties provide crucial understanding of the microscopic contributions of the coexisting phases and correlated charge transport behavior. Unlike the Grotthuss mechanism foreseen for single-ion conduction, interestingly, the findings strongly indicate that charge transport is preferentially promoted within the ether cages that act as ion channels. Impressively, ionic conductivity, σ ≅ 10−5–10−4 S cm−1 with an estimated cationic transport number, tLi+ > 0.87 at ambient temperatures and electrochemical stability >4.7 V could be achieved with composition optimization, which is almost an order more than the documented reports on single-ion conductors. A feasibility study on a LiFePO4/SIC-PE/Li system underscores their potential viability with encouraging preliminary results.

Self-Assembly of t-Butyloxycarbonyl Protected Dipeptide Methyl Esters Composed of Leucine, Isoleucine and Valine into Highly Organized Structures from Alcohol and Aqueous Alcohol Mixtures

Short peptides composed of phenylalanine and sequences derived from amyloidogenic peptides have the ability to self‐assemble to form nanostructures including hydrogels. The self‐assembly of peptides composed of only hydrophobic amino acids and aliphatic protecting groups have not been investigated in detail. We have examined various aspects of nanostructures formed by N‐terminal t‐butyloxycarbonyl‐protected aliphatic dipeptide methyl esters dissolved in various solvents. Scanning electron microscopic images indicate that depending on the sequence, position of the amino acid and solvent of dissolution, the peptides self‐assemble into superstructures such as nanotubes and needles particularly from aqueous mixtures of organic solvents. Crystallization was not required for self‐assembly into nanostructures. Circular dichroism and attenuated total internal reflection fourier transform infrared spectroscopy studies indicate that the peptides adopt β‐conformation in the superstructures both in solution and solid state. The nanostructures composed of entirely aliphatic moieties have the ability to bind to aromatic dyes such as Rhodamine 6G, Nile red and Congo red. They also bind to Thioflavin T although the structures do not resemble amyloid fibrils. The powder X‐ray diffraction patterns suggest distinctive packing of the monomers. These structures are stabilized by intermolecular hydrogen bonds and hydrophobic interactions resulting in superstructures containing long distance order and were devoid of hemolytic activity.

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.

Erratum to: Nanostructured Metal Oxides: Low Temperature Synthesis and Biomimetic Approaches

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