22 results on '"Reddicherla Umapathi"'
Search Results
2. Profiling the molecular interactions between a promising thermoresponsive polymer and ionic liquid: A biophysical outlook
- Author
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Pannuru Venkatesu, Nirmala Deenadayalu, Reddicherla Umapathi, and Payal Narang
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chemistry.chemical_classification ,Materials science ,Aqueous solution ,02 engineering and technology ,Polymer ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Lower critical solution temperature ,Smart polymer ,Atomic and Molecular Physics, and Optics ,Fluorescence spectroscopy ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,Dynamic light scattering ,chemistry ,Chemical engineering ,Ionic liquid ,Materials Chemistry ,Thermoresponsive polymers in chromatography ,Physical and Theoretical Chemistry ,0210 nano-technology ,Spectroscopy - Abstract
Thermoresponsive polymers (TRPs) that undergo significant conformation/aggregation changes in response to changes in temperature have extensive range of potential applications in various fields of science and technology. Among different types of TRPs, poly (N-isopropylacrylamide) (PNIPAM) is a suitable amphiphilic polymer for studying the conformational changes due to its biocompatible behavior with various additives. In order to get deeper insights of the TRPs in the presence of additives, we examined the collapse and aggregation of thermoresponsive polymer (PNIPAM) in aqueous solution containing variable amounts of 1-allyl-3-methylimidazolium bromide ([Amim][Br]). The influence of ionic liquid on the lower critical solution temperature (LCST) of PNIPAM aqueous solution were examined with the aid of comprehensive biophysical techniques such as UV–visible absorption spectroscopy, steady-state fluorescence spectroscopy, thermal fluorescence spectroscopy, viscosity (η) and dynamic light scattering (DLS) measurements. With the addition of 5 mg/mL of [Amim][Br] to the PNIPAM aqueous solution the LCST has been decreased towards lower temperatures. Further with the addition of higher concentration (10 and 15 mg/mL) of [Amim][Br] the decrease in the LCST of PNIPAM has been more pronounced towards lower temperatures. Our experimental results explicitly elucidated that the decrease in the LCST of the PNIPAM with increase in the concentration of [Amim][Br] is due to the substantial variations in the interactions among amide group of polymer, ions of ionic liquid and water molecules. The experimental results of the current investigation can be used for the design of smart polymer-based devices, as its LCST is close to body temperature. The results provide an alternative way to tune the phase transition temperature of the broadly accepted model PNIPAM polymer.
- Published
- 2019
3. Comprehensive adsorption characteristics of a newly synthesized and sustainable anti-corrosion catalyst on mild steel surface exposed to a highly corrosive electrolytic solution
- Author
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Hansung Kim, Ompal Singh Yadav, Raman Kumar, Gurmeet Singh, and Reddicherla Umapathi
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Langmuir ,Materials science ,Alloy ,02 engineering and technology ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Catalysis ,Corrosion ,Dielectric spectroscopy ,Adsorption ,Attenuated total reflection ,Materials Chemistry ,engineering ,Physical and Theoretical Chemistry ,0210 nano-technology ,Polarization (electrochemistry) ,Spectroscopy ,Nuclear chemistry - Abstract
A new environmental-friendly imine compound viz. 4-(2-amino-3-methylphenyl)imino)methyl)benzaldehyde (AMIB) was sustainably synthesized at room temperature utilizing green solvents, reagents and assessed as an anti-corrosion catalyst for the commercially important mild steel (MS) alloy subjected to highly aggressive 0.5 M sulphuric acid (H2SO4) solution by several electrochemical methods (polarization techniques and Electrochemical impedance spectroscopy) allied with various surface characterization techniques such as attenuated total reflectance (ATR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and atomic force microscopy (AFM). Furthermore, the experimental results were theoretically supplemented by density functional theory (DFT) treatment. AMIB delivered significant corrosion protection even at very low concentrations and at various temperatures. The findings from electrochemical and surface characterization techniques were also supplemented by temperature kinetics study. The adsorption mechanism of AMIB molecules on metal substrate follow Langmuir's adsorption isotherm. The overall corrosion mitigation mechanism assessed from various techniques and methods was found to be comprehensive in nature. The present study may pave the way for combating corrosion with this cost effective and eco-friendly strategy.
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- 2018
4. Multilayered PVDF-HFP Porous Separator via Phase Separation and Selective Solvent Etching for High Voltage Lithium-Ion Batteries
- Author
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Jong Heon Kim, Ngoc-Anh Nguyen, Liudmila L. Larina, Hyun-Suk Kim, Van-Toan Nguyen, Ho-Suk Choi, Van-Tien Bui, and Reddicherla Umapathi
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microporous membrane ,multilayer membrane ,Fabrication ,Materials science ,Separator (oil production) ,chemistry.chemical_element ,Filtration and Separation ,02 engineering and technology ,Electrolyte ,010402 general chemistry ,lcsh:Chemical technology ,01 natural sciences ,Article ,chemistry.chemical_compound ,Etching (microfabrication) ,Ultimate tensile strength ,Chemical Engineering (miscellaneous) ,lcsh:TP1-1185 ,Composite material ,lcsh:Chemical engineering ,Process Chemistry and Technology ,lcsh:TP155-156 ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Polyolefin ,Membrane ,chemistry ,Lithium ,phase separation ,0210 nano-technology - Abstract
The development of highly porous and thin separator is a great challenge for lithium-ion batteries (LIBs). However, the inevitable safety issues always caused by poor mechanical integrity and internal short circuits of the thin separator must be addressed before this type of separator can be applied to lithium-ion batteries. Here, we developed a novel multilayer poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) membrane with a highly porous and lamellar structure, through a combination of evaporation-induced phase separation and selective solvent etching methods. The developed membrane is capable of a greater amount of electrolyte uptake and excellent electrolyte retention resulting from its superior electrolyte wettability and highly porous structure, thereby offering better electrochemical performance compared to that of a commercial polyolefin separator (Celgard). Moreover, benefiting from the layered configuration, the tensile strength of the membrane can reach 13.5 MPa, which is close to the mechanical strength of the Celgard type along the transversal direction. The elaborate design of the multilayered structure allows the fabrication of a new class of thin separators with significant improvements in the mechanical and electrochemical performance. Given safer operation, the developed multilayer membrane may become a preferable separator required for high-power and high-energy storage devices.
- Published
- 2021
5. Influence of additives on thermoresponsive polymers in aqueous media: a case study of poly(N-isopropylacrylamide)
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Reddicherla Umapathi, Pannuru Venkatesu, P. Madhusudhana Reddy, and Anjeeta Rani
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chemistry.chemical_classification ,animal structures ,Phase transition temperature ,Aqueous medium ,Chemistry ,General Physics and Astronomy ,02 engineering and technology ,Polymer ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Chemical engineering ,Long period ,Poly(N-isopropylacrylamide) ,Thermoresponsive polymers in chromatography ,Physical and Theoretical Chemistry ,0210 nano-technology ,Literature survey - Abstract
Thermoresponsive polymers (TRPs) in different solvent media have been studied over a long period and are important from both scientific and technical points of view. Despite numerous studies on the behavior of TRPs with various additives, the interactions of additives with TRPs are still poorly understood. Moreover, despite the vast available literature regarding the biomolecular interactions between various TRPs and naturally occurring additives, it is not possible to provide a unifying declaration about the behavior of different additives, in particular at the phase transition temperature of the polymer. However, potential reviews that describe the behavior of additives as stimuli upon the phase transition of TRPs are also absent. A lack of sufficient knowledge regarding the responses of TRPs to additives as stimuli has hindered the expansion of the wide spectrum of applications of these polymers. Therefore, it was proposed to review the responses of TRPs in the presence of various additives in aqueous media. In-depth knowledge acquired via a literature survey has drawn our attention towards filling this gap by analyzing the interactions of TRPs with different additives. In this perspective, we have systematically examined the stability, aggregation, and phase transition behaviours of various polymers in the presence of different additives. The perspective on the influence of additives as stimuli on the behavior of TRPs in an aqueous medium will provide new reliable information about intramolecular interactions between interior polymer segments as well as intermolecular interactions between TRPs and additive molecules, which will be helpful for industrialists in the preparation of new polymeric materials for drug-delivery systems.
- Published
- 2018
6. How Does a Smart Polymer Respond to Imidazolium-Based Ionic Liquids?
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Reddicherla Umapathi, Payal Narang, Awanish Kumar, and Pannuru Venkatesu
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chemistry.chemical_classification ,Hofmeister series ,Renewable Energy, Sustainability and the Environment ,Chemistry ,General Chemical Engineering ,Inorganic chemistry ,02 engineering and technology ,General Chemistry ,Polymer ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Smart polymer ,Fluorescence ,Lower critical solution temperature ,0104 chemical sciences ,chemistry.chemical_compound ,Ionic liquid ,Environmental Chemistry ,Research article ,Fourier transform infrared spectroscopy ,0210 nano-technology - Abstract
In this research article, we have explored the changes in the lower critical solution temperature (LCST) of the poly(N-vinylcaprolactam) (PVCL) in the presence of imidazolium-based ionic liquids (ILs) with fixed cation 1-butyl-3-methylimidazolium cation [Bmim+], and commonly used anions such as SCN–, I–, Br–, Cl–, CH3COO–, and HSO4–. The series of anions also reflect the Hofmeister series of ILs. The results reveal that the LCST of the PVCL increases with increasing IL concentration. Interestingly, the results are the reverse of the PNIPAM with the same ILs where the LCST of PNIPAM decreases linearly with increase in the IL concentration following the Hofmeister series. Herein, we observed that the increase in the LCST of PVCL follows the order of ILs as, HSO4– < CH3COO– < Cl– < Br– < I– < SCN–. This is the reverse order for Hofmeister series anions effect on the polymer. Furthermore, the different kind of interactions occur between ILs and PVCL observed using UV-absorbance, fluorescence, and FTIR spectro...
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- 2017
7. Simple synthesis of a clew-like tungsten carbide nanocomposite decorated with gold nanoparticles for the ultrasensitive detection of tert-butylhydroquinone
- Author
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Seung-Kyu Hwang, Min Ji Lee, Young-Kyu Han, A.T. Ezhil Vilian, Reddicherla Umapathi, and Yun Suk Huh
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food.ingredient ,Materials science ,Sonication ,Composite number ,Metal Nanoparticles ,Chemistry Techniques, Synthetic ,Electrocatalyst ,01 natural sciences ,Soybean oil ,Nanocomposites ,Analytical Chemistry ,chemistry.chemical_compound ,0404 agricultural biotechnology ,food ,Limit of Detection ,Tungsten carbide ,Humans ,Nanotechnology ,Electrodes ,Detection limit ,Nanocomposite ,010401 analytical chemistry ,04 agricultural and veterinary sciences ,General Medicine ,Tungsten Compounds ,040401 food science ,Carbon ,Hydroquinones ,0104 chemical sciences ,chemistry ,Chemical engineering ,Colloidal gold ,Gold ,Oxidation-Reduction ,Food Science - Abstract
The excessive use of food additives in manufactured food products negatively affects their quality and potentially impacts human health. In the present study, a composite consisting of gold nanoparticles decorated on tungsten carbide (AuNP-WC) was successfully fabricated using a facile and cost-effective ultrasonication technique. Compared to a bare glassy carbon electrode (GCE), AuNP-GCE, and WC-GCE, the AuNP-WC-GCE demonstrated excellent sensing performance for tert-butylhydroquinone (TBHQ) when used as an electrocatalyst in 0.05 M phosphate buffer solution (PBS), with a low working potential and a high peak current. In particular, the composite was able to detect the oxidation of TBHQ within a linear concentration range of 5 to 75 nM, with an extremely low detection limit of 0.20 nM. The practicability of the sensor was also assessed in the analysis of TBHQ in real samples of soybean oil, blended oil, and red wine, with satisfactory recovery rates obtained.
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- 2021
8. Comprehensive Computational and Experimental Analysis of Biomaterial toward the Behavior of Imidazolium-Based Ionic Liquids: An Interplay between Hydrophilic and Hydrophobic Interactions
- Author
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Mahmoud E. S. Soliman, Pannuru Venkatesu, Suresh B. Vepuri, and Reddicherla Umapathi
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chemistry.chemical_classification ,Aqueous solution ,Absorption spectroscopy ,Chemistry ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Hydrophobic effect ,chemistry.chemical_compound ,Dynamic light scattering ,Ionic liquid ,Materials Chemistry ,Physical chemistry ,Organic chemistry ,Physical and Theoretical Chemistry ,Fourier transform infrared spectroscopy ,0210 nano-technology ,Spectroscopy ,Alkyl - Abstract
To provide insights into the aggregation behavior, hydration tendency and variation in phase transition temperature produced by the addition of ionic liquids (ILs) to poly(N-isopropylacrylamide) (PNIPAM) aqueous solution, systematic physicochemical studies, and molecular dynamic simulations were carried out. The influence of ILs possessing the same [Cl]− anion and a set of cations [Cnmim]+ with increasing alkyl chain length such as 1-ethyl-3-methylimidazolium ([Emim]+), 1-allyl-3-methylimidazolium ([Amim]+), 1-butyl-3-methylimidazolium ([Bmim]+), 1-hexyl-3-methylimidazolium ([Hmim]+), 1-benzyl-3-methylimidazolium ([Bzmim]+), and 1-decyl-3-methylimidazolium ([Dmim]+) on the phase transition of PNIPAM was monitored by the aid of UV–visible absorption spectra, fluorescence intensity spectra, viscosity (η), dynamic light scattering (DLS), and Fourier transform infrared (FTIR) spectroscopy. Furthermore, to interpret the direct images and surface morphologies of the PNIPAM–IL aggregates, we performed field emis...
- Published
- 2017
9. Thermo-responsive triblock copolymer phase transition behaviour in imidazolium-based ionic liquids: Role of the effect of alkyl chain length of cations
- Author
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Reddicherla Umapathi and Pannuru Venkatesu
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Hofmeister series ,Ionic Liquids ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Chloride ,Micelle ,Phase Transition ,Polyethylene Glycols ,Biomaterials ,chemistry.chemical_compound ,Drug Delivery Systems ,Colloid and Surface Chemistry ,Dynamic light scattering ,Cations ,Borates ,Polymer chemistry ,medicine ,Micelles ,Alkyl ,chemistry.chemical_classification ,Aqueous solution ,Viscosity ,Chemistry ,Imidazoles ,Temperature ,technology, industry, and agriculture ,Water ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Propylene Glycols ,Ionic liquid ,0210 nano-technology ,Ethylene glycol ,medicine.drug - Abstract
Different biophysical techniques such as fluorescence spectroscopy, dynamic light scattering (DLS), viscosity (η) and Fourier transform infrared (FTIR) spectroscopy have been carried out to characterize the effect of imidazolium-based ionic liquids (ILs) on the thermo-responsive triblock copolymer, poly(ethylene glycol)-block-poly(propylene glycol)-block-poly-(ethylene glycol) (PEG-PPG-PEG). In addition, to demonstrate the distinct morphological changes of various self-assembled morphologies, we further employed field emission scanning electron microscope (FESEM). To investigate the effect of alkyl chain length of the cation, concentration of the ILs and the related Hofmeister series on the phase behaviour of PEG-PPG-PEG, we used a series of ILs possessing same Cl- anion and a set of cation [Cnmim]+ with increasing alkyl chain length of cation such as 1-ethyl-3-methylimidazolium chloride ([Emim][Cl]), 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]), 1-hexyl-3-methylimidazolium chloride ([Hmim][Cl]) and 1-decyl-3-methylimidazolium chloride ([Dmim][Cl]). The critical micellization temperature (CMT) of the copolymer in the presence of well hydrated cations is directly correlated to their hydration. The overall specific ranking of ILs in decreasing the CMT of PEG-PPG-PEG in aqueous solution was [Emim][Cl]>[Bmim][Cl]>[Hmim][Cl]>[Dmim][Cl]. The trend of these ILs followed the well-known Hofmeister series of cations of ILs. The present study provides important information about the solution properties that can be helpful to tune the IL or temperature-sensitive copolymer CMT and micelle shapes which are crucial for understanding the drug delivery mechanisms.
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- 2017
10. The influence of various alkylammonium-based ionic liquids on the hydration state of temperature-responsive polymer
- Author
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Nirmala Deenadayalu, Pannuru Venkatesu, Thandeka Yvonne Mhkize, and Reddicherla Umapathi
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chemistry.chemical_classification ,Aqueous solution ,Chemistry ,02 engineering and technology ,Polymer ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Lower critical solution temperature ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Hydrophobic effect ,chemistry.chemical_compound ,Chemical engineering ,Dynamic light scattering ,Polymer chemistry ,Ionic liquid ,Materials Chemistry ,Poly(N-isopropylacrylamide) ,Physical and Theoretical Chemistry ,0210 nano-technology ,Spectroscopy ,Temperature-responsive polymer - Abstract
The influence of different alkylammonium-based ionic liquids (ILs) on the temperature-dependent aqueous poly( N -isopropylacrylamide) (PNIPAM) solution is explored by the comprehensive experimental analysis. The co-solvents investigated in the present study included a series of ILs with a fixed (trifluromethylsulfonyl)imide [NTf 2 ] − anion and variable ammonium cations such as butyltrimethylammonium (IL-1), methyl-trioctylammonium (IL-2), diethylmethyl(2-methoxyethyl)ammonium (IL-3) and ethyldimethylpropylammonium (IL-4). The thermal phase transitions of aqueous solution of thermo-responsive polymer (TRP) in ammonium-based ILs were studied by various experimental techniques such as fluorescence spectroscopy, dynamic light scattering (DLS) and viscosity ( η ). We further employed field emission scanning electron microscope (FESEM) to reveal the distinct morphological changes of various self-assembled morphologies. Our results reveal that the lower critical solution temperature (LCST) of the TRP can be significantly altered by the ILs. The phase transition state of aqueous TRP decreases as the concentration of IL increased. We find that IL-4 lowers the LCST of TRP significantly more as compared to the other ILs. Our experimental results reveal that the hydrophobic interactions are predominant between the monomers of PNIPAM and ions of the ILs. This research work highlights new opportunities for the wide applications in engineering of the bio-responsive smart PNIPAM-based devices and appropriate selection of ILs, which should allow for increasing the usage of thermo-responsive phase behaviour of polymers.
- Published
- 2017
11. Influence of biological stimuli on the phase behaviour of a biomedical thermoresponsive polymer: A comparative investigation of hemeproteins
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Krishan Kumar, Pannuru Venkatesu, Gokana Mohana Rani, and Reddicherla Umapathi
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Hemeproteins ,Hemeprotein ,Polymers ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Lower critical solution temperature ,Smart polymer ,Phase Transition ,Protein–protein interaction ,Biomaterials ,Colloid and Surface Chemistry ,Phase (matter) ,Humans ,Thermoresponsive polymers in chromatography ,chemistry.chemical_classification ,biology ,Cytochrome c ,Temperature ,Water ,Polymer ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry ,Biophysics ,biology.protein ,0210 nano-technology - Abstract
Hypothesis Thorough knowledge of the biomolecular interactions between thermoresponsive polymers (TRPs) and proteins are necessary to fabricate potential materials for various bio-related science and technology applications. Although over the past four decades have evidenced that tremendous growth in the utilization of TRPs in the addition of various stimuli systems, a underlying molecular origins of the role of biological stimuli on TRPs phase transition is still missing. Experiments We demonstrated the comparative effect of heme proteins (biological stimuli) such as cytochrome c (Cyt c) and myoglobin (Mb) on the phase behaviour of poly(N-isopropylacrylamide) (PNIPAM) aqueous solution. The sophisticated multiple techniques have confirmed that the structural integrity of the proteins is found to play a vital role in altering the phase transition temperature of PNIPAM to different extents with increasing the concentration of proteins. Findings With the addition of Cyt c, the lower critical solution temperature (LCST) of PNIPAM (33.0 °C) increased towards higher temperature (35.7 °C) in contrast to this with the addition of Mb the LCST of PNIPAM decreased towards lower temperature (30.7 °C). This discrepancy is due to the difference in contrast structural arrangements of both proteins on the LCST of PNIPAM. On the basis of these results, the variation in the structures of both heme proteins, hydration and dehydration between the heme proteins are compared. These results demonstrated that depending on the type of smart polymers used for bio-related applications, it is necessary to take into account the effect of biological stimuli while designing polymers. We hope that the present study can stimulate more novel concepts and dramatic changes in smart polymer and protein interactions.
- Published
- 2018
12. Fabrication of Carbon Disulfide Added Colloidal Gold Colorimetric Sensor for the Rapid and On-Site Detection of Biogenic Amines
- Author
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Yun Suk Huh, Youngjin Cho, Reddicherla Umapathi, Namhyeok Choi, Min Ji Lee, Bum Jun Park, and Seo Yeong Oh
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Absorption spectroscopy ,education ,Inorganic chemistry ,Metal Nanoparticles ,Nanoparticle ,biogenic amines ,Gold Colloid ,lcsh:Chemical technology ,01 natural sciences ,Biochemistry ,Article ,colloidal gold ,Analytical Chemistry ,symbols.namesake ,0404 agricultural biotechnology ,parasitic diseases ,lcsh:TP1-1185 ,Electrical and Electronic Engineering ,Dithiocarbamate ,Absorption (electromagnetic radiation) ,Instrumentation ,Detection limit ,chemistry.chemical_classification ,colorimetric sensor ,010401 analytical chemistry ,04 agricultural and veterinary sciences ,carbon disulfide ,040401 food science ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,chemistry ,Colloidal gold ,on-site detection ,symbols ,Colorimetry ,Amine gas treating ,Gold ,Raman spectroscopy - Abstract
Meat is often wasted due to the perceived concerns of its shelf life and preservation. Specifically, in meat formation, biogenic amines (BAs) are the major agents to spoil them. Herein, we have developed a carbon disulfide (CS2) added colloidal gold nanoparticles-based colorimetric sensor for the rapid and on-site detection of biogenic amines. Transmission electron microscopy is used to observe the morphological changes in colloidal gold nanoparticles and aggregation behavior of CS2 added to the colloidal gold nanoparticles’ solution. Raman spectroscopic analysis is further used to characterize the peaks of CS2, Cad and CS2-Cad molecules. Absorption spectroscopy is used to estimate the colorimetric differences and diffuse reflectance spectra of the samples. The sensing analysis is performed systematically in the presence and absence of CS2. CS2 added colloidal gold nanoparticles colorimetric sensor detected the BAs with a limit of detection (LOD) value of 50.00 µM. Furthermore, the developed sensor has shown an LOD of 50.00 µM for the detection of multiple BAs at a single time. The observed differences in the colorimetric and absorption signals indicate that the structure of BAs is converted to the dithiocarbamate (DTC)-BA molecule, due to the chemical reactions between the amine groups of BAs and CS2. Significantly, the developed colorimetric sensor offers distinct features such as facile fabrication approach, on-site sensing strategy, rapid analysis, visual detection, cost-effective, possibility of mass production, availability to detect multiple BAs at a single time and appreciable sensitivity. The developed sensor can be effectively used as a promising and alternative on-site tool for the estimation of BAs.
- Published
- 2021
13. Controllable synthesis of bottlebrush-like ZnO nanowires decorated on carbon nanofibers as an efficient electrocatalyst for the highly sensitive detection of silymarin in biological samples
- Author
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Yun Suk Huh, Young-Kyu Han, Sangjin Lee, Cheol Woo Oh, Seung-Kyu Hwang, Kugalur Shanmugam Ranjith, A.T. Ezhil Vilian, and Reddicherla Umapathi
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Detection limit ,Materials science ,Nanocomposite ,Carbon nanofiber ,Metals and Alloys ,Nanowire ,chemistry.chemical_element ,Nanotechnology ,Context (language use) ,02 engineering and technology ,Zinc ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Electrocatalyst ,Electrochemistry ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry ,Materials Chemistry ,Electrical and Electronic Engineering ,0210 nano-technology ,Instrumentation - Abstract
The excessive intake of antioxidant drugs due to veterinary and human medical treatment poses serious health risks to both humans and animals. In this context, the monitoring of antioxidant drugs in animal and human biological systems is important and has provoked a universal scientific challenge. Therefore, it is of the utmost importance to develop cost-effective electrochemical sensing electrode materials for the sensing of bio-analytes and pharmaceutical drugs in biological samples. In this work, electro-etched carbon nanofibers (CNFs) were coated with bottlebrush-like zinc oxide (ZnO) nanowires via a facile hydrothermal method for the preparation of a CNF-ZnO nanocomposite as a promising electrode material for the trace level detection of silymarin. The fabricated CNF-ZnO glassy carbon electrode (GCE) demonstrated a higher anodic peak current, lower peak potential, and excellent sensing performance of silymarin compared to GCEs fabricated with ZnO or CNFs. The CNF-ZnO-GCE exhibited an appreciable linear response range (2–123 nM), good sensitivity (1.728 μA∙nM−1 cm2), and an ultra-low detection limit (1 nM). We also successfully showcased its specific sensing behavior for the sensing of silymarin in the presence of structurally similar compounds and metal ions. Furthermore, the CNF-ZnO-GCE was effectively applied to real biological and pharmacological samples for the efficient determination of silymarin, with which we obtained satisfactory recovery values.
- Published
- 2020
14. Effect of temperature on molecular interactions between tri(butyl)methylphosphonium methylsulfate and furfural
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Indra Bahadur, Deresh Ramjugernath, C. Narasimha Rao, Reddicherla Umapathi, Pannuru Venkatesu, and Paramespri Naidoo
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Molecular interactions ,Work (thermodynamics) ,Isentropic process ,Chemistry ,Intermolecular force ,Analytical chemistry ,02 engineering and technology ,010402 general chemistry ,Furfural ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Viscosity ,chemistry.chemical_compound ,020401 chemical engineering ,General Materials Science ,0204 chemical engineering ,Physical and Theoretical Chemistry - Abstract
In this work, the effect of temperature on the molecular interactions between tri(butyl)methylphosphonium methylsulfate ([P4441][CH3SO4]) and furfural were studied over the entire composition range, temperature ranging from (293.15 to 323.15) K and at pressure 0.1 MPa, using the measured density (ρ), ultrasonic sound velocities (u) and viscosity (η) data. The excess molar volumes (VE), partial molar volumes ( V ¯ 1 and V ¯ 2 ), excess partial molar volumes ( V 1 E ¯ and V 2 E ¯ ), deviation in isentropic compressibilities (Δκs) and the deviation in viscosities (Δη) were evaluated using these properties as a function of the concentration of IL. The Redlich-Kister polynomial was used to correlate the VE, Δκs and Δη data. The intermolecular interactions and structural effects are analysed on the basis of the measured and derived properties. Such knowledge about the intermolecular interactions which occur between ([P4441][CH3SO4]) with furfural is beneficial in the development of structure–property correlations as well as new predictive models.
- Published
- 2020
15. Solution Behavior of Triblock Copolymer in the Presence of Ionic Liquids: A Comparative Study of Two Ionic Liquids Possessing Different Cations with Same Anion
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Reddicherla Umapathi and Pannuru Venkatesu
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Aqueous solution ,Materials science ,Renewable Energy, Sustainability and the Environment ,General Chemical Engineering ,Inorganic chemistry ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Chloride ,Fluorescence spectroscopy ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Dynamic light scattering ,Ionic liquid ,medicine ,Copolymer ,Environmental Chemistry ,Physical chemistry ,0210 nano-technology ,Spectroscopy ,Ethylene glycol ,medicine.drug - Abstract
A comparative study of two ionic liquids (ILs) with same anion and different cations on the phase transition changes of aqueous solution of a commonly used triblock copolymer poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEG–PPG–PEG) (or Pluronic F-108), is undertaken using fluorescence spectroscopy, dynamic light scattering (DLS), viscosity (η), Fourier transform infrared (FT-IR) spectroscopy and nuclear magnetic resonance (NMR) techniques. Furthermore, to demonstrate it by direct visualization of various self-assembled morphologies, we employed field emission scanning electron microscope (FESEM). The two ILs include 1-allyl-3-methylimidazolium chloride ([Amim][Cl]) and 1-benzyl-3-methylimidazolium chloride ([Bzmim][Cl]). The results demonstrate that the addition of ILs alter the critical micellization temperature (CMT) toward lower temperatures. The extent to which the CMT altered is observed to be significantly more for [Bzmim][Cl] as compared to [Amim][Cl]. The charge...
- Published
- 2016
16. Hierarchical dense Ni−Co layered double hydroxide supported carbon nanofibers for the electrochemical determination of metronidazole in biological samples
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Seung-Kyu Hwang, Kugalur Shanmugam Ranjith, Yun Suk Huh, Reddicherla Umapathi, A.T. Ezhil Vilian, Young-Kyu Han, Sangjin Lee, and Cheol Woo Oh
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Detection limit ,Materials science ,Carbon nanofiber ,General Chemical Engineering ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,Electrocatalyst ,01 natural sciences ,0104 chemical sciences ,Cathodic protection ,Electrochemical gas sensor ,chemistry.chemical_compound ,Chemical engineering ,chemistry ,Electrode ,Hydroxide ,0210 nano-technology - Abstract
Scientific research reports have shown that long-term use of chemical and biological drugs such as Metronidazole (MNZ) can lead to certain human health issues due to its genotoxic, genotypic, carcinogenic and mutagenic type side effects in the biological samples. Therefore, the rapid exploration and rational design of electrocatalyst materials, reliable electrochemical techniques, and essential strategies to fabricate novel electrochemical sensing devices for the detection of drugs in the biological samples are of utmost interest. Herein, we developed a facile strategy to fabricate a novel electrode material consisting of conductive hierarchical dense nickel-cobalt layered double hydroxide material grown on electrospun carbon nanofibers (CNF–NiCo-LDH), which was synthesized via a simple hydrothermal method. Because of their hierarchical dense unique interconnected architecture, the CNF–NiCo-LDH deposited onto a glassy carbon electrode (GCE) exhibited improved electrocatalytic response toward metronidazole (MNZ). The fabricated electrode delivered a higher cathodic peak current for MNZ at a low peak potential of −0.54 V in the presence of 20 μM MNZ in 0.05 M phosphate-buffered solution ((PBS; pH 7). The fabricated electrode showed a wide linear response for the reduction of MNZ at concentrations from 3 to 57 nM, an extremely lower detection limit (LOD) of 0.13 nM, and a high sensitivity of 1.294 μA nM−1 cm−2. The developed electrode also showed interference-free sensing performance and excellent long-term stability. Because of its electrochemical performance, the CNF–NiCo-LDH-GCE provides a simple, fast, and effective electrochemical sensor for the detection of MNZ at the ultra-trace level in industrial and pharmaceutical applications.
- Published
- 2020
17. Enhanced anticancer activity of half-sandwich Ru(II)-p-cymene complex bearing heterocyclic hydrazone ligand
- Author
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Nattamai Bhuvanesh, Jebiti Haribabu, Reddicherla Umapathi, Dasararaju Gayathri, Ramasamy Karvembu, Swaminathan Srividya, and Pannuru Venkatesu
- Subjects
chemistry.chemical_classification ,p-Cymene ,biology ,Ligand ,Hydrazone ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,biology.organism_classification ,01 natural sciences ,Medicinal chemistry ,Sodium methoxide ,0104 chemical sciences ,Inorganic Chemistry ,HeLa ,chemistry.chemical_compound ,chemistry ,Materials Chemistry ,Ic50 values ,Hydrazone ligand ,Physical and Theoretical Chemistry ,0210 nano-technology ,Single crystal - Abstract
The hydrazone ligand (HL) was synthesized from furan-2-carbohydrazide and indole-3-carboxaldehyde. The reaction of [RuCl2(p-cymene)]2 with HL in the presence of sodium methoxide yielded organometallic Ru(II)-p-cymene compound of the type [RuCl(η6-p-cymene)(η2-N,O-indole hydrazone)] (1). The ligand and complex were characterized by CHN analysis and various spectroscopic tools. The piano stool (pseudo-octahedral) geometry of the complex was confirmed by single crystal X-ray diffraction. The anticancer property of the ligand and complex was investigated against A549, HeLa and MCF7 cancer cell lines. The complex exhibited superior activity against A549 and HeLa cancer cells with the IC50 values of 23.4 and 12.9 µM, respectively.
- Published
- 2020
18. Unravelling the interactions between biomedical thermoresponsive polymer and biocompatible ionic liquids
- Author
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Pannuru Venkatesu, Reddicherla Umapathi, João A. P. Coutinho, and Imran Khan
- Subjects
02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Lower critical solution temperature ,Hydrophobic effect ,chemistry.chemical_compound ,PNIPAM ,Dynamic light scattering ,Phase (matter) ,Cholinium ionic liquids ,Materials Chemistry ,Thermoresponsive polymers in chromatography ,Physical and Theoretical Chemistry ,Spectroscopy ,Aqueous solution ,Hydrogen bond ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Phase transition behavior ,chemistry ,Ionic liquid ,Physical chemistry ,Aggregation behavior ,0210 nano-technology - Abstract
Studies on the phase behavior of thermoresponsive polymers (TRPs) in the presence of ionic liquids (ILs) are an emerging area for the preparation and design of new polymeric materials. The search to understand the influence of ILs on polymers has come into the limelight as a great challenge. Hitherto, limited work on the phase transition behavior of TRPs in the presence of ILs is available. In this work, we studied the phase behavior of poly-N-isopropylacrylamide (PNIPAM) in presence of cholinium chloride ([Ch]Cl), cholinium acetate ([Ch][Ac]), cholinium bitartrate ([Ch][Bit]) and cholinium dihydrogen citrate ([Ch][DHCit]) using various techniques such as UV–Visible absorption spectroscopy, steady-state fluorescence spectroscopy, thermal fluorescence spectroscopy, viscosity (ƞ) and dynamic light scattering (DLS). All cholinium-based ILs studied show qualitatively and quantitatively a similar phase behavior, suggesting it to be quite resilient with respect to changes in the anion of the ILs. However, concentration and orientation of ILs have a varied effect on the phase transition temperature and on the aggregation behavior of PNIPAM. Our temperature dependent experimental results explicitly signifies that lower critical solution temperature (LCST) values decrease with increasing the temperature and concentration of studied ILs, which indicates that hydrophobic interactions are dominating. Anions of IL with their charge densities, hydration capacities and hydration energies leads to the hydrophobicity of PNIPAM + IL aqueous solution. High polarity, owing to the charge of the carboxylate groups in [Ch][DHCit] and [Ch][Bit], and hydrogen bond acceptor capability of the Cl− anion causes their affinity for water inducing ability. This is the first report on the influence of cholinium-based ILs on the phase behavior of the PNIPAM. The current research work provides significant information on the phase transition and aggregation behavior of TRPs in ILs, which paves the way for potential applications in various fields.
- Published
- 2020
19. Investigation of temperature and composition dependence of molecular interactions between phosphonium-based ionic liquid + N, N-dimethylformamide: A study of thermophysical properties
- Author
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Paramespri Naidoo, Pannuru Venkatesu, Reddicherla Umapathi, Indra Bahadur, and Deresh Ramjugernath
- Subjects
Materials science ,Isentropic process ,Hydrogen bond ,Intermolecular force ,Thermodynamics ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Solvent ,chemistry.chemical_compound ,Molar volume ,Volume (thermodynamics) ,chemistry ,Volume fraction ,Ionic liquid ,Materials Chemistry ,Physical and Theoretical Chemistry ,0210 nano-technology ,Spectroscopy - Abstract
Understanding the thermophysical properties of ionic liquids (ILs) with organic solvents is crucial for the development of industrial applications. In this study densities (ρ), ultrasonic sound velocities (u) and viscosities (η) for binary mixtures of tri(butyl) methylphosphonium methylsulfate ([P4441][CH3SO4]) with N,N-dimethylformamide (DMF) were measured over the entire composition range at various temperatures (293.15–323.15 K) and at 0.1 MPa pressure. From ρ, u and η data, derived properties such as deviation in viscosities (Δη), excess molar volumes (VE) deviation in isentropic compressibilities (Δκs), mixture molar volume (Vm) volume fraction (θ1) excess expansion volume coefficient (αEp) and adiabatic compressibility (ks) and excess adiabatic compressibility (ksE), Partial molar volumes ( V ¯ 1 and V ¯ 2 ) and excess partial molar volumes ( V ¯ 1 E and V ¯ 2 E ) were calculated. For all the systems studied, negative to positive VE values were obtained while the Δκs and Δη values are negative, over the entire composition range and at all the studied temperatures. Results for these experimental and derived properties have been studied on the basis of intermolecular interactions between the components of the mixtures and in terms of hydrogen bonding, ion-dipole interaction and interstitial packing between ions of IL and molecular solvent. These experimental results and derived properties are beneficial for defining the molecular modelling, developing structure-property correlation and intermolecular interactions that occur between tri(butyl) methylphosphonium methylsulfate with DMF.
- Published
- 2019
20. Quantifying the influence of ionic liquid on the phase behaviour of a biomedical thermoresponsive polymer: A biophysical experimental approach
- Author
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Nirmala Deenadayalu, Reddicherla Umapathi, Krishan Kumar, and Pannuru Venkatesu
- Subjects
Polymers and Plastics ,Chemistry ,General Chemical Engineering ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Biochemistry ,Lower critical solution temperature ,Fluorescence spectroscopy ,0104 chemical sciences ,chemistry.chemical_compound ,Differential scanning calorimetry ,Dynamic light scattering ,Phase (matter) ,Ionic liquid ,Materials Chemistry ,Environmental Chemistry ,Physical chemistry ,Thermoresponsive polymers in chromatography ,Fourier transform infrared spectroscopy ,0210 nano-technology - Abstract
Thermoresponsive polymers (TRPs) are known to exhibit changes in conformational states, with a change in the solution temperature. Obviously, temperature is the key factor that responds to the conformational transition behavior of TRPs. Among various TRPs, poly (N-vinylcaprolactam) (PVCL) is a suitable amphiphilic polymer for the study of conformational changes due to its compatible behavior with various additives. In the current study, the effect of 1-allyl-3-methylimidazolium bromide ([Amim][Br]) on phase transition behavior of PVCL aqueous solution was studied. In order to investigate the alterations on phase behavior of PVCL in [Amim][Br], various biophysical techniques such as ultraviolet-visible absorption spectroscopy, steady-state fluorescence spectroscopy, Fourier transform infrared (FTIR) spectroscopy, thermal fluorescence spectroscopy, dynamic light scattering (DLS) and differential scanning calorimetry (DSC) were used. Our experimental results explicitly elucidated that [Amim][Br] increases the lower critical solution temperature (LCST) of PVCL with increasing the concentration of ionic liquid (IL). The main rationale observed is attributed to the IL interaction affinity depending on its cationic and anionic part's affinity towards water molecules that are strongly attached to the bonds in pure PVCL and become more attracted to the IL and thus resulted in the facilitation of hydrated form of PVCL.
- Published
- 2019
21. Assessing the efficiency of imidazolium-based ionic liquids on the phase behavior of a synthetic biomedical thermoresponsive polymer
- Author
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Reddicherla Umapathi and Pannuru Venkatesu
- Subjects
Phase transition ,Hot Temperature ,Polymers ,Chemical structure ,Ionic Liquids ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Lower critical solution temperature ,Biomaterials ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,Phase (matter) ,Polymer chemistry ,chemistry.chemical_classification ,Aqueous solution ,Chemistry ,Imidazoles ,Solution polymerization ,Polymer ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Ionic liquid ,Physical chemistry ,0210 nano-technology - Abstract
Hypothesis Temperature-responsive polymers (TRPs) with a phase transition temperature close to human physiological body temperature have attracted much attention in biomedical and pharmaceutical fields. Addition of small amount of cosolvent to TRPs is expected to influence the molecular interactions, thereby affecting the phase transition temperature of TRPs. Hence, it is possible to tune the phase behavior of TRPs and also drive transitions in TRPs by variation of chemical structure of cosolvent. Experiments To elucidate the conformational changes of the phase transition of TRP aqueous solution in ionic liquids (ILs), poly(N-vinylcaprolactam) (PVCL), a well known TRP was synthesized by solution polymerization. The lower critical solution temperature (LCST) behavior of polymer aqueous solution, with the addition of imidazolium-based ILs possessing same Cl− anion and a set of cations [Cnmim]+ such as 1-ethyl-3-methylimidazolium ([Emim]+), 1-butyl-3-methylimidazolium ([Bmim]+), 1-hexyl-3-methylimidazolium ([Hmim]+), 1-decyl-3-methylimidazolium ([Dmim]+), 1-allyl-3-methylimidazolium ([Amim]+) and 1-benzyl-3-methylimidazolium ([Bzmim]+), was monitored by using various sophisticated experimental techniques. Findings The modulations on the LCST of PVCL aqueous solutions follow the order of [Emim][Cl]
- Published
- 2017
22. Structural insights into the effect of cholinium-based ionic liquids on the critical micellization temperature of aqueous triblock copolymers
- Author
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Imran Khan, Pannuru Venkatesu, João A. P. Coutinho, Márcia C. Neves, and Reddicherla Umapathi
- Subjects
Materials science ,Scanning electron microscope ,General Physics and Astronomy ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Fluorescence spectroscopy ,AMPHIPHILIC BLOCK-COPOLYMERS ,FTIR SPECTROSCOPY ,chemistry.chemical_compound ,BIPHASIC SYSTEMS ,AGGREGATION BEHAVIOR ,Dynamic light scattering ,POLYETHYLENE-GLYCOL ,PEG ratio ,Polymer chemistry ,Copolymer ,WATER ,Physical and Theoretical Chemistry ,PPG-PEG-PPG ,Aqueous solution ,MICELLAR SYSTEMS ,technology, industry, and agriculture ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,TETRAETHYLENE GLYCOL ,chemistry ,Ionic liquid ,0210 nano-technology ,Ethylene glycol ,PHASE-SEPARATION - Abstract
Symmetrical poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEG-PPG-PEG) triblock copolymer with 82.5% PEG as the hydrophilic end blocks, and PPG as the hydrophobic middle block, was chosen to study the effect of ionic liquids (ILs) on the critical micellization temperature (CMT) of block copolymers in aqueous solution. In the present work, cholinium-based ILs were chosen to explore the effect of the anions on the copolymer CMT using fluorescence spectroscopy, dynamic light scattering (DLS), viscosity (η), FT-IR spectroscopy, nuclear magnetic resonance (NMR), and direct visualization of the various self-assembled nanostructures by scanning electron microscopy (SEM). The result suggests that ILs have the ability to decrease the CMT of the aqueous copolymer solution which is dependent on the nature of the anions of the ILs. The present study reveals that the hydrophobic part PPG of the copolymer has more influence on this behavior than the PEG hydrophilic part.
- Published
- 2016
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