Browsing by Author "Dutta, NK"

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    3D printed graphene aerogels using conductive nanofibrillar network formulation
    (Elsevier, 2023-06) Tran, TS; Balu, R; Mata, JP; Dutta, NK; Choudhury, NR
    Despite recent progress in 3D printing of graphene, formulation of aqueous 3D printable graphene inks with desired rheological properties for direct ink writing (DIW) of multifunctional graphene macrostructures remains a major challenge. In this work, we develop a novel 3D printable pristine graphene ink in aqueous phase using conductive nanofibrillar network formulation by controlling the interfacial interactions between graphene and PEDOT:PSS nanofibrils. The formulated inks, tailored for energy applications, provide excellent 3D printability for fabricating multilayer 3D structures (up to 30 layers) with spanning features and high aspect ratio. The 3D printed aerogels, comprising interconnected networks of graphene flakes and PEDOT:PSS nanofibrils, exhibit excellent electrical conductivity as high as ∼630 S m − 1 and can be converted into conductive hydrogels via swelling in water/electrolyte. The formulated graphene inks were used for fabricating 3D printed supercapacitor electrodes (power density of 11.3 kW kg−1 and energy density of 7.3 Wh kg−1) with excellent performance and durability. © 2023 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license.
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    An16-resilin: An advanced multi-stimuli-responsive resilin-mimetic protein polymer
    (Elsevier, 2014-11-01) Rajkamal, B; Dutta, NK; Choudhury, NR; Elvin, CM; Lyon, RE; Knott, RB; Hill, AJ
    Engineered protein polymers that display responsiveness to multiple stimuli are emerging as a promising class of soft material with unprecedented functionality. The remarkable advancement in genetic engineering and biosynthesis has created the opportunity for precise control over the amino acid sequence, size, structure and resulting functions of such biomimetic proteins. Herein, we describe the multi-stimuli-responsive characteristics of a resilin-mimetic protein, An16-resilin (An16), derived from the consensus sequence of resilin gene in the mosquito Anopheles gambiae. We demonstrate that An16 is an intrinsically disordered protein that displays unusual dual-phase thermal transition behavior along with responsiveness to pH, ion, light and humidity. Identifying the molecular mechanisms that allow An16 to sense and switch in response to varying environments furthers the ability to design intelligent biomacromolecules. © 2014 Acta Materialia Inc.
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    Composite polymer electrolyte containing ionic liquid and functionalized polyhedral oligomeric silsesquioxanes for anhydrous PEM applications
    (American Chemical Society, 2009-06-24) Subianto, S; Mistry, MK; Choudhury, NR; Dutta, NK; Knott, RB
    A new type of supported liquid membrane was made by combining an ionic liquid (IL) with a Nafion membrane reinforced with multifunctional polyhedral oligomeric silsesquioxanes (POSSs) using a layer-by-layer strategy for anhydrous proton-exchange membrane (PEM) application. The POSS was functionalized by direct sulfonation, and the sulfonated POSS (S-POSS) was incorporated into Nafion 117 membranes by the infiltration method. The resultant hybrid membrane shows strong ionic interaction between the Nafion matrix and the multifunctional POSS, resulting in increased glass transition temperature and thermal stability at very low loadings of S-POSS (1%). The presence of S-POSS has also improved the proton conductivity especially at low humidities, where it shows a marked increase due to its confinement in the ionic domains and promotes water uptake by capillary condensation. In order to achieve anhydrous conductivity, the IL 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMI-BTSI) was incorporated into these membranes to provide proton conduction in the absence of water. Although the incorporation of an IL shows a plasticizing effect on the Nafion membrane, the S-POSS composite membrane with an IL shows a higher modulus at high temperatures compared to Nafion 117 and a Nafion−IL membrane, with significantly higher proton conductivity (5 mS/cm at 150°C with 20% IL). This shows the ability of the multifunctional POSS and IL to work symbiotically to achieve the desirable proton conductivity and mechanical properties of such membranes by enhancing the ionic interaction within the material. © 2009, American Chemical Society
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    Effects of crowding and environment on the evolution of conformational ensembles of the multi-stimuli-responsive intrinsically disordered protein, Rec1-resilin: a small-angle scattering investigation
    (American Chemical Society, 2016-06-09) Balu, R; Mata, JP; Knott, RB; Elvin, CM; Hill, AJ; Choudhury, NR; Dutta, NK
    In this study, we explore the overall structural ensembles and transitions of a biomimetic, multi-stimuli-responsive, intrinsically disordered protein (IDP), Rec1-resilin. The structural transition of Rec1-resilin with change in molecular crowding and environment is evaluated using small-angle neutron scattering and small-angle X-ray scattering. The quantitative analyses of the experimental scattering data using a combination of computational models allowed comprehensive description of the structural evolution, organization, and conformational ensembles of Rec1-resilin in response to the changes in concentration, pH, and temperature. Rec1-resilin in uncrowded solutions demonstrates the equilibrium intrinsic structure quality of an IDP with radius of gyration Rg ∼ 5 nm, and a scattering function for the triaxial ellipsoidal model best fit the experimental dataset. On crowding (increase in concentration >10 wt %), Rec1-resilin molecules exert intermolecular repulsive force of interaction, the Rg value reduces with a progressive increase in concentration, and molecular chains transform from a Gaussian coil to a fully swollen coil. It is also revealed that the structural organization of Rec1-resilin dynamically transforms from a rod (pH 2) to coil (pH 4.8) and to globular (pH 12) as a function of pH. The findings further support the temperature-triggered dual-phase-transition behavior of Rec1-resilin, exhibiting rod-shaped structural organization below the upper critical solution temperature (∼4 °C) and a large but compact structure above the lower critical solution temperature (∼75 °C). This work attempted to correlate unusual responsiveness of Rec1-resilin to the evolution of conformational ensembles. © 2016 American Chemical Society
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    Environment-induced self-assembly in phase separated block copolymer systems
    (The Bragg Institute, Australian Nuclear Science and Technology Organisation, 2005-11-27) Dutta, NK; Thompson, S; Choudhury, NR; Knott, RB
    Polymer chain sequence with different repeating unit and thermodynamic incompatibility between the segments can be chemically linked together through covalent bonds to form block copolymers of unique ordered microstructure and characteristics. Such block copolymers are characterized by fluid-like disorder ion the molecular scale and a high degree of morphological order at longer length scales, resulting in complex equilibrium phase behaviors, giving rise to a large variety of microdomain structures. A specific block copolymer may be optimum nanomaterial, either for their intrinsic properties as self-organized assemblies; or could be used as a strategy to template the organization of the desired inorganic. semi-conducting, metallic or biologically relevant materials into particles, nano planes, wires, or spheres within the polymer matrix. The amphiphilic block copolymers that self-assemble in selective solvents are also of significant scientific interest and of extensive importance in the field of controlled drug delivery systems, detergents, paints, cosmetics, oil recovery.. The situation is versatile and complicated since for a block copolymer system a solvent that is good for one block may be neutral, slightly selective, or strongly selective, or a non-solvent for the other block/ls. in multiblock copolymer with selective solvents the dramatic expansion of parameter space poses both experimental and theoretical challenges; and there has been very limited systematic research on the environment-induced self-organization of the phase behavior of triblock copolymer. ln this research work the effect of selective solvent and temperature on the phase behavior of a polystyrene-b-(ethylene-co-butylene)-b-styrene triblock copolymer (SEBS) are presented. We examine the adaptive nature of the ordering in asymmetric block copolymers, using a small angle neutron scattering techniques (SANS). The effect of solvent selectivity and temperature on the evolution of the scattering pattern and trends of the interference maximum in the lovv q (structure factor related to interdomain interference and indicates relatively higher level of ordering of the micelle cores) and high q regimes (form factor related to the contribution of the smaller intradomain distances) has been monitored. The organizational behavior has also been confirmed using Atomic force microscopy (AFM), transmission electron microscopy (TEM) and rheolgical investigation. Morphological evolution of the self-assembled phase behavior of such polymer with the thermodynamic selectivity of solvent, temperature, heat treatment, and time will been discussed in detail. © The Authors
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    Environment-induced self-assembly in phase separated block copolymer systems: a SANS investigation
    (Elsevier B. V., 2006-11-15) Dutta, NK; Thompson, S; Choudhury, NR; Knott, RB
    In this research, we examine the effect of non-selective solvent on the large-scale mesoscopic ordering in asymmetric block copolymers, poly(styrene-block-ethylene/butylene-block-styrene) (SEBS) using small angle neutron scattering technique (SANS). SANS measurements were carried out over a wide range of concentrations and temperatures. Evolution of the self-assembled phase morphology in such polymer with the thermodynamic selectivity of solvent, temperature and concentration has been discussed. Correlation between morphology and thermorheological behavior of the gels has also been established. © 2006 Elsevier B.V.
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    A genetically engineered protein responsive to multiple stimuli
    (Wiley-Blackwell, 2011-04-06) Dutta, NK; Truong, MY; Mayavan, S; Choudhury, NR; Elvin, CM; Kim, M; Knott, RB; Nairn, KM; Hill, AJ
    Smart protein: Careful design can yield novel biologically inspired materials that display advanced responsive behavior. A genetically engineered elastic protein displays both a lower and an upper critical solution temperature (LCST and UCST, see picture), and its photophysical behavior depends on solution pH value.
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    Inorganic modification of block copolymer for medium temperature proton exchange membrane application
    (Elsevier, 2010-04-01) Mistry, MK; Choudhury, NR; Dutta, NK; Knott, RB
    New hybrid membranes have been developed via sol–gel chemistry and solvent directed infiltration method using novel inorganic precursors and sulfonated poly(styrene-b-[ethylene-co-butylene]-b-styrene) (S-SEBS). S-SEBS shows a distinct phase separated morphology which can be used as a structure directing template to drive the inorganic component within the ionic domains of the polymer. Photoacoustic Fourier transform infrared spectroscopy (PA-FTIR) confirms the formation of Si–O–Si and Si–O–P bridges in hybrid membranes which indicate a silicate or phosphosilicate network structure within the hybrid membranes. The presence of the inorganic network within the hybrid membranes improves their thermal stability, viscoelastic properties and water retention at elevated temperatures above 100°C. Scanning electron microscopy (SEM) results show a uniform distribution of the inorganic component within the hybrid membranes and confirm successful incorporation of inorganic particles within S-SEBS membranes. Conductivity of S-SEBS starts to decrease after 60°C due to excessive swelling whereas hybrid membranes show an increase in conductivity after 60°C as the inorganic component reduces excessive swelling in hybrid membranes. SAXS results indicate that S-SEBS has distinct phase separated morphology and show hybrid membranes exhibit a lamellar morphology. © 2010, Elsevier Ltd.
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    Ionic liquid based nanoparticle emulsions as a corrosion inhibitor
    (Australian Institute of Nuclear Science and Engineering, 2016-11-29) Mata, JP; Taghavikish, M; Subianto, S; Dutta, NK; de Campo, L; Rehm, C; Choudhury, NR
    In this contribution, we report the facile preparation of cross-linked polymerizable ionic liquid (PIL)-based nanoparticles via thiol–ene photopolymerization in a miniemulsion. The synthesized PIL nanoparticles with a diameter of about 200 nm were fully characterized with regard to their chemical structures, morphologies, and properties using different techniques, such as Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and transmission electron microscopy [1]. To gain an in-depth understanding of the physical and morphological structures of the PIL nanoparticles in an emulsion, small angle neutron scattering and ultra-small-angle neutron scattering were used. Neutron scattering studies revealed valuable information regarding the formation of cylindrical ionic micelles in the spherical nanoparticles, which is a unique property of this system. Furthermore, the PIL nanoparticle emulsion was utilized as an inhibitor in a self-assembled nanophase particle (SNAP) coating. The corrosion protection ability of the resultant coating was examined using potentiodynamic polarization and electrochemical impedance spectroscopy. The results show that the PIL nanoparticle emulsion in the SNAP coating acts as an inhibitor of corrosion and is promising for fabricating advanced coatings with improved barrier function and corrosion protection [1].
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    Ionic liquid based nanoparticle emulsions as a corrosion inhibitor
    (International Conference on Neutron Scattering, 2017-07-12) Mata, JP; Taghavikish, M; Subianto, S; Dutta, NK; de Campo, L; Rehm, C; Choudhury, NR
    In this contribution, we report the facile preparation of cross-linked polymerizable ionic liquid (PIL)-based nanoparticles via thiol–ene photopolymerization in aminiemulsion. The synthesized PIL nanoparticles with a diameter of about 200 nmwere fully characterized with regard to their chemical structures, morphologies, and properties using different techniques, such as Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electronmicroscopy, and transmission electron microscopy [1]. To gain an in-depth understanding of the physical and morphological structures of the PIL nanoparticles in an emulsion, small-angle neutron scattering and ultra-small-angle neutron scattering were used. Neutron scattering studies revealed valuable information regarding the formation of cylindrical ionic micelles in the spherical nanoparticles, which is a unique property of this system. Furthermore, the PIL nanoparticle emulsion was utilized as an inhibitorin a self-assembled nanophase particle (SNAP) coating. The corrosion protectionability of the resultant coating was examined using potentio dynamic polarization and electrochemical impedance spectroscopy. The results show that the PIL nanoparticle emulsion in the SNAP coating acts as an inhibitor of corrosion and is promising for fabricating advanced coatings with improved barrier function and corrosion protection [1].
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    Nanostructure evolution in high-temperature perfluorosulfonic acid ionomer membrane by small-angle x-ray scattering
    (American Chemical Society, 2010-12-21) Mistry, MK; Choudhury, NR; Dutta, NK; Knott, RB
    The high-temperature morphology of supported liquid membranes (SLMs) prepared from perfluorinated membranes such as Nafion and Hyflon and hydrophobic ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMI-TFSI) has been investigated by small-angle X-ray scattering (SAXS). Proton conductivity results of SLMs before and after leaching show an increase in conductivity with temperature up to 160°C in an anhydrous environment. DSC results show that crystallites within perfluorinated membranes are thermally stable up to 196°C. High-temperature SAXS results have been used to correlate structure and morphology of supported liquid membranes with high-temperature conductivity data. The ionic liquid essentially acts as a proton solvent in a similar way to water in hydrated Nafion membranes and increases size of clusters, which allow percolation to be achieved more easily. The cation of the ionic liquid interacts with sulfonate groups within ionic domains through electrostatic interactions and displaces protons. Protons can associate with free anions of the ionic liquid, which are loosely associated with cations and can transport by hopping from anion sites within the membrane. The ionic liquid contributes to proton conductivity at high temperature through achievement of long-range ordering and subsequent percolation. © 2010, American Chemical Society
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    Near superhydrophobic fibrous scaffold for endothelialization: fabrication, characterization and cellular activities
    (American Chemical Society, 2013-10-04) Ahmed, F; Choudhury, NR; Dutta, NK; Zannettino, A; Knott, RB
    In this work, we have applied an electrospinning method to control wettability and further hydrophobic modification of a hydrophobic polymer mat of poly(vinylidene fluoride-co hexafluoropropylene). A correlation between the processing parameters, rheological properties of polymer solutions, and electrospinning ability was made using the polymer’s critical entanglement concentration, the boundary between the semidilute unentangled regime and the semidilute entangled regime. The wetting behavior, structural and thermal characteristics of electrospun (ES) mats were evaluated and compared with solvent cast sample using advancing and receding contact angle analyses, differential scanning calorimetry, and small-angle X-ray scattering. To demonstrate the feasibility, the best optimized ES samples were examined for their potential and ability to support bone marrow derived endothelial cell seeding efficiency, adhesion and proliferation. Our studies show that, while different processing techniques can effectively modulate physical and morphological changes such as porosity and hydrophobicity, the cellular adhesion and proliferation are highly time-dependent and controlled by chemical factors. As such, these results suggest that it is the interplay of both physical and chemical factors that determine the endothelialization of porous near superhydrophobic scaffolds. The developed electrospun samples demonstrate their feasibility for endothelialization. © 2013, American Chemical Society.
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    Novel organic-inorganic hybrids with increased water retention for elevated temperature proton exchange membrane application
    (American Chemical Society, 2008-11-11) Mistry, MK; Choudhury, NR; Dutta, NK; Knott, RB; Shi, ZQ; Holdcroft, S
    A new class of proton-conducting hybrid membranes have been developed using it combination of a solvent-directed infiltration method and sol-gel chemistry with a range of organofunctional silane and phosphate precursors. The phase-separated morphology of Nafion is used as a structure-directing template, which drives the inorganic component into the ionic Clusters of the Nafion membrane. The kinetics of the sol-gel reactions were monitored using spectroscopic techniques. Photoacoustic Fourier transform infrared spectroscopy (PA-FTIR) confirms formation of Si-O-Si and Si-O-P bridges in the hybrid membranes, indicating silicate and phosphosilicate structures. The presence of the silicate/phosphosilicate network in the hybrid membranes enhances their thermal stability, thermomechanical properties, water retention at elevated temperatures, and relaxation temperature T(c). Scanning electron microscopy (SEM) and small angle neutron scattering were used to determine the morphology and microstructure of these membranes. A structural model of the hybrids is proposed to describe the size and shape of the inorganic particles, which is consistent with the SEM observations. Proton conductivity measurements were made from 30 to 80 degrees C and at relative humidities ranging from 30% to 90%. The presence of inorganics in the polymer membrane has improved the water management in these new organic-inorganic hybrids at elevated temperatures above 100 degrees C, which is a key parameter when designing proton-ex change membranes for medium-temperature fuel cell application. © 2008, American Chemical Society
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    Polymeric ionic liquid nanoparticle emulsions as a corrosion inhibitor in anticorrosion coatings
    (American Chemical Society, 2016-07-06) Taghavikish, M; Subianto, S; Dutta, NK; de Campo, L; Mata, JP; Rehm, C; Choudhury, NR
    In this contribution, we report the facile preparation of cross-linked polymerizable ionic liquid (PIL)-based nanoparticles via thiol–ene photopolymerization in a miniemulsion. The synthesized PIL nanoparticles with a diameter of about 200 nm were fully characterized with regard to their chemical structures, morphologies, and properties using different techniques, such as Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and transmission electron microscopy. To gain an in-depth understanding of the physical and morphological structures of the PIL nanoparticles in an emulsion, small-angle neutron scattering and ultra-small-angle neutron scattering were used. Neutron scattering studies revealed valuable information regarding the formation of cylindrical ionic micelles in the spherical nanoparticles, which is a unique property of this system. Furthermore, the PIL nanoparticle emulsion was utilized as an inhibitor in a self-assembled nanophase particle (SNAP) coating. The corrosion protection ability of the resultant coating was examined using potentiodynamic polarization and electrochemical impedance spectroscopy. The results show that the PIL nanoparticle emulsion in the SNAP coating acts as an inhibitor of corrosion and is promising for fabricating advanced coatings with improved barrier function and corrosion protection. Open Access © 2016 American Chemical Society
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    Structural ensembles reveal intrinsic disorder for the multi-stimuli responsive bio-mimetic protein rec1-resilin
    (Springer Nature, 2015-06-04) Balu, R; Knott, RB; Cowieson, NP; Elvin, CM; Hill, AJ; Choudhury, NR; Dutta, NK
    Rec1-resilin is the first recombinant resilin-mimetic protein polymer, synthesized from exon-1 of the Drosophila melanogaster gene CG15920 that has demonstrated unusual multi-stimuli responsiveness in aqueous solution. Crosslinked hydrogels of Rec1-resilin have also displayed remarkable mechanical properties including near-perfect rubber-like elasticity. The structural basis of these extraordinary properties is not clearly understood. Here we combine a computational and experimental investigation to examine structural ensembles of Rec1-resilin in aqueous solution. The structure of Rec1-resilin in aqueous solutions is investigated experimentally using circular dichroism (CD) spectroscopy and small angle X-ray scattering (SAXS). Both bench-top and synchrotron SAXS are employed to extract structural data sets of Rec1-resilin and to confirm their validity. Computational approaches have been applied to these experimental data sets in order to extract quantitative information about structural ensembles including radius of gyration, pair-distance distribution function, and the fractal dimension. The present work confirms that Rec1-resilin is an intrinsically disordered protein (IDP) that displays equilibrium structural qualities between those of a structured globular protein and a denatured protein. The ensemble optimization method (EOM) analysis reveals a single conformational population with partial compactness. This work provides new insight into the structural ensembles of Rec1-resilin in solution. © 2017 Macmillan Publishers Limited, part of Springer Nature
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    Structural evolution of photocrosslinked silk fibroin and silk fibroin-based hybrid hydrogels: a small angle and ultra-small angle scattering investigation
    (Elsevier, 2018-07-15) Whittaker, JL; Balu, R; Knott, RB; de Campo, L; Mata, JP; Rehm, C; Hill, AJ; Dutta, NK; Choudhury, NR
    Regenerated Bombyx mori silk fibroin (RSF) is a widely recognized protein for biomedical applications; however, its hierarchical gel structure is poorly understood. In this paper, the hierarchical structure of photocrosslinked RSF and RSF-based hybrid hydrogel systems: (i) RSF/Rec1-resilin and (ii) RSF/poly(N-vinylcaprolactam (PVCL) is reported for the first time using small-angle scattering (SAS) techniques. The structure of RSF in dilute to concentrated solution to fabricated hydrogels were characterized using small angle X-ray scattering (SAXS), small angle neutron scattering (SANS) and ultra-small angle neutron scattering (USANS) techniques. The RSF hydrogel exhibited three distinctive structural characteristics: (i) a Porod region in the length scale of 2 to 3 nm due to hydrophobic domains (containing β-sheets) which exhibits sharp interfaces with the amorphous matrix of the hydrogel and the solvent, (ii) a Guinier region in the length scale of 4 to 20 nm due to hydrophilic domains (containing turns and random coil), and (iii) a Porod-like region in the length scale of few micrometers due to water pores/channels exhibiting fractal-like characteristics. Addition of Rec1-resilin or PVCL to RSF and subsequent crosslinking systematically increased the nanoscale size of hydrophobic and hydrophilic domains, whereas decreased the homogeneity of pore size distribution in the microscale. The presented results have implications on the fundamental understanding of the structure–property relationship of RSF-based hydrogels. © 2018 Elsevier B.V.
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    Tuning the hierarchical structure and resilience of resilin-like polypeptide hydrogels using graphene oxide
    (American Chemical Society, 2020-11-24) Balu, R; Dorishetty, P; Mata, JP; Hill, AJ; Dutta, NK; Choudhury, NR
    Resilin-like polypeptides (RLPs) are an important class of intrinsically disordered multistimuli-responsive bioelastomers. The nanostructure of RLPs in solution has been extensively studied in the past few years, from dilute to molecular crowding conditions, and with the addition of rigid biopolymers. Modification of the hierarchical network structure of RLP hydrogels using graphene oxide (GO) as an additive is a burgeoning prospect for their application in the bioelectronic and biomedical fields. In this work, we systemically study the influence of incorporating GO into RLP (Rec1) hydrogels for tuning their physicochemical properties and understanding the gel–cell interactions. The nature of GO interaction with the Rec1 hydrogel is deduced from the change in structure and properties. Contrast-matching small-angle and ultra-small-angle neutron-scattering techniques were used to investigate the network structure of the Rec1 hydrogel and how this structure is modified in the presence of GO. Incorporation of GO in the Rec1 hydrogel matrix results in an increase in the micromechanical resilience, equilibrium water swelling ratio, micropore size, cross-linked domain size; with a decrease in the cross-link density, mass fractal cluster size, local compressive elastic modulus, and cell inert characteristics. These property combinations achieved with the addition of GO further open up the available structure–property design window for RLP applications. © 2020 American Chemical Society