A5069852433- Surfactants and Colloidal Systems
- Supramolecular Self-Assembly in Materials
- Hydrogels: synthesis, properties, applications
- Lipid Membrane Structure and Behavior
- Pickering emulsions and particle stabilization
- Crystallization and Solubility Studies
- Advanced Materials and Mechanics
- X-ray Diffraction in Crystallography
- Advanced Sensor and Energy Harvesting Materials
- Innovative Microfluidic and Catalytic Techniques Innovation
- Polymer Surface Interaction Studies
- Material Dynamics and Properties
- Advanced Polymer Synthesis and Characterization
- Polymer Nanocomposites and Properties
- Rheology and Fluid Dynamics Studies
- Microfluidic and Capillary Electrophoresis Applications
- 3D Printing in Biomedical Research
- Porphyrin and Phthalocyanine Chemistry
- Polydiacetylene-based materials and applications
- Nanoparticle-Based Drug Delivery
- Spectroscopy and Quantum Chemical Studies
- Liquid Crystal Research Advancements
- Oil Spill Detection and Mitigation
- Hemostasis and retained surgical items
- Polymer crystallization and properties
University of Maryland, College Park
2016-2025
Tech Mahindra (India)
2023
Park University
2014-2021
Indian Institute of Science Bangalore
2017-2019
Bioengineering Center
2017
University of Warwick
2015
Jawaharlal Institute of Post Graduate Medical Education and Research
2012
University of Maryland, Baltimore
2012
University of Baltimore
2012
Tamkang University
2009
Cationic surfactants having long (C22) mono-unsaturated tails were studied in aqueous solutions containing salt using steady and dynamic rheology. The surfactant erucyl bis(hydroxyethyl)methylammonium chloride self-assembles into giant wormlike micelles, giving rise to unusually strong viscoelasticity. Under ambient conditions, the viscosity enhancement due exceeds a factor of 107. Some samples behave as gel-like solids at low temperatures revert viscoelastic (Maxwellian) response only...
Dispersions of hydrophilic fumed silica are investigated in a range polar organic media. The forms stable, low-viscosity sols exhibiting shear thickening behavior host liquids, including ethylene glycol and its oligomers short-chain alcohols, such as n-propanol. In contrast, the flocculates into colloidal gels other glycols with methyl end-caps longer-chain alcohols. We suggest that there is causal relationship between hydrogen-bonding ability liquid microstructure observed. strongly...
Unilamellar vesicles are observed to form in aqueous solutions of the cationic surfactant, cetyl trimethylammonium bromide (CTAB), when 5-methyl salicylic acid (5mS) is added at slightly larger than equimolar concentrations. When these heated above a critical temperature, they transform into long, flexible wormlike micelles. In this process, switch from low-viscosity, Newtonian fluids viscoelastic, shear-thinning having much zero-shear viscosities (e.g., 1000-fold higher). The onset...
Mopping up: Phase-selective gelators were synthesized from sugar alcohols using biocatalysis. The exhibited an unprecedented ability to phase-selectively gel only organic liquids including crude-oil fractions in the presence of water at room temperature. Oil can be recovered gelled phase by heating and distillation. Thus this class materials may useful recovering oil spills.
A highly porous 2D nanomaterial, holey graphene oxide (hGO), is synthesized directly from powder and employed to create an aqueous 3D printable ink without the use of additives or binders. Stable dispersions hydrophilic hGO sheets in water (≈100 mg mL-1 ) can be readily achieved. The shear-thinning behavior enables extrusion-based printing fine filaments into complex architectures, such as stacked mesh structures, on arbitrary substrates. freestanding printed meshes exhibit trimodal...
Abstract Rechargeable Li–S batteries are regarded as one of the most promising next‐generation energy‐storage systems. However, inevitable formation Li dendrites and shuttle effect lithium polysulfides significantly weakens electrochemical performance, preventing its practical application. Herein, a new class localized high‐concentration electrolyte (LHCE) enabled by adding inert fluoroalkyl ether 1H,1H,5H‐octafluoropentyl‐1,1,2,2‐tetrafluoroethyl into highly‐concentrated electrolytes (HCE)...
The self-assembly of nanotubes from chiral amphiphiles and peptide mimics is still poorly understood. Here, we present the first complete path to by studied with C12-β12 (N-α-lauryl-lysyl-aminolauryl-lysyl-amide), a molecule designed have unique hybrid architecture. Using technique direct-imaging cryo-transmission electron microscopy (cryo-TEM), show time-evolution micelles closed nanotubes, passing through several types one-dimensional (1-D) intermediates such as elongated fibrils, twisted...
Polymer hydrogels synthesized by chemical cross-linking of acrylate or acrylamide monomers can absorb more than 100 times their weight in water. However, such gels are usually fragile and rupture when stretched to moderate strains (∼50%). Many strategies have been developed create tougher gels, including double-networking, incorporation nanoparticles as cross-linkers, etc., but these typically retard the water absorbency gel. Here, we present a new approach that gives rise superabsorbent...
Self-assembly in mixtures of cationic and anionic surfactants occurs synergistically because attractive interactions between the oppositely charged headgroups. Here, such effects are exploited to obtain highly viscoelastic fluids at low total surfactant concentration. The systems considered C18-tailed surfactant, sodium oleate (NaOA), from trimethylammonium bromide family (CnTAB). In particular, NaOA C8TAB show remarkably high viscosities: for 3% zero-shear viscosity η0 peaks ca. 1800 Pa·s a...
A systematic electrical and rheological characterization of percolation in commercial polydisperse polystyrene (PS) nanocomposites containing multiwall carbon nanotubes (MWCNTs) is presented. The MWCNTs confer appreciable conductivities (up to ca. 1 S/m) these at a concentration 8 vol %. In addition enhancing the properties, even small concentrations (ca. 2 %), significantly enhance properties PS melts. At exceeding %, plateau appears storage modulus G' low frequencies, indicating formation...
The 22-carbon-tailed zwitterionic surfactant erucyl dimethyl amidopropyl betaine (EDAB) forms highly viscoelastic fluids in water at low concentrations and without the need for salt or other additives. Here, semidilute aqueous solutions of EDAB are studied by using a combination rheological techniques, small-angle neutron scattering (SANS) cryo-transmission electron microscopy (cryo-TEM). samples show interesting rheology as function temperature. At temperatures (∼25 °C), 50 mM sample...
The addition of low concentrations the hydrotropic salt p-toluidine hydrochloride (PTHC) to solutions anionic surfactant sodium dodecyl sulfate (SDS) promotes transition from spherical rodlike micelles. NMR measurements confirm that hydrotrope adsorbs at micelle−water interface, thereby screening electrostatic repulsions between headgroups. sphere-to-rod in dilute is followed using quasielastic light scattering, and semidilute concentration range dynamic rheology used probe viscoelastic...
Small-angle neutron scattering (SANS) and rheology are used to probe the wormlike micelles formed in mixtures of a cationic (cetyl trimethylammonium tosylate, CTAT) an anionic surfactant (sodium dodecyl benzene sulfonate, SDBS). For fixed composition 97/3 CTAT/SDBS, zero-shear viscosity η0 initially increases rapidly with concentration, but decreases beyond intermediate concentration φmax. The solutions show peak SANS height also exhibits maximum around These results interpreted terms linear...
A simple and effective means for obtaining hollow silica particles of controlled diameter from about 60 to 120 nm is presented. The synthesis utilizes equilibrium vesicles as templates the directed growth silica. Two different surfactant systems are used form vesicular templates: (a) mixtures cetyltrimethylammonium bromide (CTAB) sodium perfluorooctanoate (FC7) (b) tosylate (CTAT) dodecylbenzenesulfonate (SDBS). These were chosen because these surfactants in water unilamellar spontaneously...
The kinetics and mode of nucleation growth fibers by 5α-cholestan-3β-yl N-(2-naphthyl)carbamate (CNC), a low-molecular-mass organogelator (LMOG), in n-octane n-dodecane have been investigated as their sols were transformed isothermally to organogels. has followed detail circular dichroism, fluorescence, small-angle neutron scattering, rheological methods. When treated according Avrami theory, kinetic data from the four methods are self-consistent describe gelation process involving...
Photorheological (PR) fluids, i.e., those with light-tunable rheological properties, may be useful in a variety of applications, such as sensors and microfluidic devices. Currently, the need to synthesize complex photosensitive molecules hampers applicability these fluids. Here, we report simple class PR fluids that require no special synthesis can easily replicated any lab from inexpensive chemicals. The consist cationic surfactant, cetyl trimethylammonium bromide (CTAB), photoresponsive...
The kinetics of the isothermal transformation sols, comprised a low molecular-mass organogelator (LMOG) and an organic liquid, to their organogel phases have been followed by circular dichroism (CD), fluorescence, small angle neutron scattering (SANS), rheological methods. thixotropic properties (in sense that severe shearing rest lead reestablishment viscoelasticity) gels examined as well measurements. compositions samples were either 5α-cholestan-3β-yl N-(2-naphthyl) carbamate (CNC) in...
Cationic surfactants with an erucyl (C22, monounsaturated) tail display unusual phase behavior in aqueous solution as a function of temperature and added salt concentration. Low amounts salts binding counterions such sodium tosylate (NaTos) lead to highly viscoelastic wormlike micellar solutions. With further addition salt, the viscosity decreases, solutions cloud on heating (i.e., exhibit lower consolute behavior). The cloud-point zero-shear η0 pass parallel through minima NaTos Cloud-point...