Dr. Koomkoom Khawas

Editorial Board Members of ChemArticle & ChemClip; M.Sc, Ph.D (Chemistry)

Achievement

• Current Position: Assistant Professor of Chemistry; HOD; Examination Controller of RKDF University Ranchi
• Description: Currently working as an Assistant Professor in Chemistry. My research interest lies in Organic Synthesis and Polymer Chemistry. I am dedicated to teaching students. Qualified with CSIR-NET and GATE and also awarded with CSIR-SRF. The main aim is to teach the students in the best possible ways.
• Teaching Experience: 10 Years
• Email: ----

• CRITICAL STUDY OF GROUND WATER QUALITY IN RANCHI CITY

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• December 7, 2020➧ Journal of Critical Reviews ➧ JCR. 2020: 5300-5303
• The importance of water as a resource and life preservative is well known to us. The majority of human activities, including eating, drinking, bathing, cleaning, washing, farming, working in an industry, having fun, fishing, and navigating, require it. The world's surface is covered by water to a depth of about 75%. Because of its high salt content, the oceans, which contain 97% of the earth's water, are unfit for human usage. Only 1% of the remaining 2% is available as fresh water in rivers, lakes, streams, reservoirs, and ground water that is safe for human consumption. The remaining 2% is frozen in polar ice caps. Even though the world has made great strides in all areas of science and technology, many people still have a long way to go before they can access adequate and clean drinking water. The uneven distribution of water is to blame for this. This research paper reflects critical study of Ground Water Quality in Ranch City.. Read More

• Efficient Moisture-Induced Energy Harvesting from Water-Soluble Conjugated Block Copolymer-Functionalized Reduced Graphene Oxide

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• December 2023 ➧ ACS Omega 2021, 6, 11, 7257–7265 ➧ DOI: https://doi.org/10.1021/acsomega.0c03717 ➧ Copyright © 2021 The Authors. Published by American Chemical Society. ➧ License: CC-BY-NC-ND 4.0.
• This Research Article demonstrates a very simple approach of a moisture-induced power-generating phenomenon using water-soluble rod-coil conjugated block copolymer (poly(3-hexythiophene)-block-poly(4-styrenesulfonic acid) (P3HT-b-PSSA)-modified reduced graphene oxide. The block copolymer-modified reduced graphene oxide (BCP-RGO) was prepared by noncovalent surface functionalization cum in situ reduction of graphene oxide. A simple device made from BCP-RGO can generate voltage upon exposure to water vapor or under different humidity conditions. The open-circuit voltage generated from the diode-like device varies with respect to the relative humidity, and the device can act as a self-powered humidity sensor. The as-prepared BCP-RGO is able to produce a maximum power density of 1.15 μW/cm2 (short-circuit current density JSC = 6.40 μA/cm2) at a relative humidity of 94%. Meanwhile, the BCP-RGO device produces a very high power density of 0.7 mW/cm2 (at a short-circuit current density of 1.06 mA/cm2) after 91% water absorption. We believe that the material presented here will be very useful for a self-biased humidity sensor and moisture-induced energy harvesting. The diode-like response of the BCP-RGO device with humidity or after water absorption will make the material applicable for self-biased humidity-controlled electronic switching... Read More

• Simple and Direct Synthetic Route to a Rod–Coil Conjugated Block Copolymer from Either a Rod or Coil Block Using a Single Bifunctional Initiator: A Solvent Dependent Self-Assembly and Field Effect Mobility Study

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• February 14, 2020 ➧ ACS Appl. Polym. Mater. 2020, 2, 3, 1283–1293 ➧ DOI: https://doi.org/10.1021/acsapm.9b01158 ➧Copyright © 2020 American Chemical Society ➧ Request Reuse Permission
• Here, we have described a simple and straightforward methodology for synthesis of rod–coil conjugated block copolymer poly(3-hexylthiophene)-block-polystyrene (P3HT-b-PS) of varying molecular weight and low polydispersity by chain extension of either a rod or coil block starting from a single bifunctional initiator through combination of Kumada catalyst transfer polymerization (KCTP) and atom transfer radical polymerization (ATRP). Advantages of the present method include the facile synthesis of the Ni(II) catalytic initiators from readily available laboratory reagents, avoiding high reactive intermediates for preparing Ni(ii) catalytic initiator, and the in situ nature of all the steps making large scale preparation of the block copolymer viable. Studies on solvent-induced structure formation and their impact on optical and electronic properties of the block copolymer were systematically performed. The block copolymer device fabricated from toluene shows the best field effect mobility of (2.1 ± 0.75) × 10–3 cm2 V–1 s–1 compared to results for other solvents. Overall, this work describes a facile synthetic strategy for a rod–coil conjugated block copolymer and its solvent-induced structure formation as guidance for fabricating high-performance organic electronic and optoelectronic devices... Read More

• Highly Water-Soluble Rod–Coil Conjugated Block Copolymer for Efficient Humidity Sensor

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• July 24, 2019 ➧ Macromol. Chem. Phys. 2019, 1900013. ➧ DOI: https://doi.org/10.1002/macp.201900013
• In this report, the preparation of highly water-soluble rod–coil conjugated block copolymer poly(3-hexylthiophene)-b-polystyrenesulfonic acid (P3HT-b-PSSA) is demonstrated using a facile method with its moisture sensing properties. The block copolymer synthesis method comprises Kumada catalyst transfer polymerization and atom transfer radical polymerization from a bifunctional initiator followed by sulfonation of polystyrene using moderate reaction conditions. The polymerization results in the synthesis of well-defined block copolymers with controllable block length. The successful synthesis of the block copolymer is studied by NMR and FTIR spectroscopy while optical and structural properties of the block copolymer are investigated using UV–vis, photoluminescence spectroscopy, XRD, and FESEM. In water, the block copolymer shows aggregated structure with crystalline core formed by rod-like P3HT chain with absorption maxima at 558 nm, whereas in solid state the absorption maxima is blue shifted to 548 nm... Read More

• Aligned Proton Conducting Graphene Sheets via Block Copolymer Supramolecular Assembly and Their Application for Highly Transparent Moisture Sensing Conductive Coating.

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• 02 July 2019 ➧ Chemistry Select, C 2019, 4, 7523 –7531 ➧ DOI: https://doi.org/10.1002/slct.201900662
• Here, we have demonstrated a well-defined strategy to prepare highly sulphonated reduced graphene oxide (S-rGO) sheets via non-covalent modification of rGO with water soluble rod-coil conjugated block copolymer poly(3-hexylthiophene)-block-poly(4-styrenesulfonic acid) (P3HT-b-PSSA) carrying a long PSSA block. S-rGO sheets are highly water soluble and its aqueous solution can be used to fabricate highly transparent conductive thin film coating on versatile smooth substrate surfaces like glass, indium tin oxide (ITO), quartz and flexible PET. The successful anchoring of sulfonic acid group on rGO surface via non-covalent modification by P3HT-b-PSSA was confirmed and analyzed by FTIR and XRD study. The bulk morphology of S-rGO reveals sheet like morphology where individual sheets are aligned with each other in a parallel arrangement through intercalation of PSSA chains driven by block copolymer self- assembly. AFM image of the thin film also supports nice parallel alignment of S-rGO sheets of average thickness ∼100 nm on substrate surface. S-rGO sample shows very high water uptake (∼91% in comparison to its initial weight) and proton conductivity 0.5 S/cm after water vapor exposure for 1 hour. Such high proton conductivity is due to the synergy of alignment of graphene sheets with a continuous network of proton conducting nanochannels created by block copolymer microphase separation on the rGO surface. Nyquist plot with two semicircles suggested the presence of grain boundaries in the sample. I−V measurement of transparent thin film device fabricated from S-rGO sheets shows linear behavior with systematic increase of current on increasing water vapor exposure time. .. Read More

• Synthesis of End Functionalized Regioregular Poly(3-Hexyl thiophene) by Catalytic-Initiated Kumada Catalyst Transfer Polymerization.

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• 15 March 2019 ➧ Journal of Polymer Science Part A: Polymer Chemistry ➧ DOI: https://doi.org/10.1002/pola.29349
• A simple but efficient route to the preparation of aromatic end‐functionalized regioregular poly(3‐hexyl thiophene) through catalytic initiated Kumada catalyst transfer polymerization from easily accessible reagents is reported here. The introduction of aromatic moiety at one end of the poly(3‐hexyl‐thiophene) (P3HT) chain was confirmed by NMR, by MALDI‐TOF analysis, and also by successful syntheis of rod–coil‐conjugated block copolymer either from a proper end‐functionalized P3HT or from a end‐functionalize coil polymer... Read More

• Electrochemical and Electronic Properties of Transparent Coating from Highly Solution Processable Graphene Using Block Copolymer Supramolecular Assembly: Application toward Metal Ion Sensing and Resistive Switching Memory.

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• June 29, 2018 ➧ ACS Omega 2018, 3, 6, 7106–7116 ➧ DOI: https://doi.org/10.1021/acsomega.8b00883 ➧ Copyright © 2018 American Chemical Society. ➧ Request reuse permissions
• Here, we have discussed the preparation of a highly solution processable graphene from a novel supramolecular assembly consisting of block copolymer polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) and pyrenebutyric acid (PBA)-modified reduced graphene oxide (RGO). The PBA molecules anchored on the graphene surface form supramolecules with PS-b-P4VP through H-bonding between the carboxylic acid group of 1-pyrenebutyric acid and the pyridine ring of P4VP. The formation of a supramolecular assembly results in a highly stable solution of reduced graphene oxide in common organic solvents, such as 1,4-dioxane and chloroform. Highly transparent and mechanically stable thin films can be deposited from these supramolecular assemblies on a relatively smooth surface of different substrates such as silicon wafer, glass, indium tin oxide, and flexible polymer substrates like poly(ethylene terephthalate)... Read More

• Hierarchical Polyaniline-MnO2-Reduced Graphene Oxide Ternary Nanostructures with Whiskers-Like Polyaniline for Supercapacitor Application.

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• 19 December 2017 ➧ Chemistry Select 2017, 1, 1 –8 ➧ DOI: https://doi.org/10.1002/slct.201702345 ➧ Copyright © 2018 American Chemical Society. ➧ Request reuse permissions
• Here, we have demonstrated a straight forward and easy synthetic route for preparation of three dimensional hierarchical and porous polyaniline (PANI)/manganese dioxide (MnO2)/reduced graphene oxide (rGO) ternary hybrid nanomaterials with surface decorated by ordered PANI whiskers. The nanostructured material shows different well defined morphology like tubular fiber, sphere which resembles natural tubular wiregrass sedge and spherical cactus. The simple removal of graphene surface modifier through selective dissolution from nanohybrids results further porous structure. The ternary hybrid materials show varying capacitance values depending on composition and nanostructured morphology with the best capacitance value of 762 F/g at current density 1.4 A/g with good electrochemical stability... Read More

• Enhanced Charge Carrier Mobility and Tailored Luminescence of n-Type Organic Semiconductor through Block Copolymer Supramolecular Assembly.

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• 02 March 2017 ➧ Macromolecular Chemistry and Physics 2017, 218, 1600508. ➧ DOI: https://doi.org/10.1002/macp.201600508
• Herein, a novel and viable strategy to fabricate fully solution processable nanostructured n-type organic semiconducting material through block copolymer supramolecular assembly consisting of polystyrene-b-poly(4-vinyl pyridine) (PS-b-P4VP) and an asymmetric perylenebisimide (PBI) has been demonstrated. The block copolymer supramolecular assemblies show hierarchical structure formation in two length scales (lamella within lamella) from synergistic phase separation of block copolymer and PBI molecule inside the comb block. The optical and luminescent studies clearly evidence that the nature of aggregation of the PBI molecules inside the P4VP domain through facial π–π stacking is modified with tailored luminescent properties compared to its pure state. The block copolymer supramolecular assembly with 1:1 mole ratio (4-vinyl pyridine:PBI) shows almost three-order enhancement of charge carrier mobility compared to pristine PBI though it has only (0.571) of PBI weight fraction. It is believed that the organic semiconductor polymeric system described here will be useful for preparing luminescent materials, organic electronic and optoelectronic devices... Read More

• Polyaniline graphene nanohybrid with three dimensional pillar structures for high performing electrochemical supercapacitor applications.

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• 1 February 2016 ➧ Electrochimica Acta 2016, 190, 596–604. ➧ DOI: https://doi.org/10.1016/j.electacta.2015.12.130
• A simple but efficient route based on supramolecular approach for large scale synthesis of intercalated polyaniline graphene nanohybrid with three dimensional pillar structures is described. The selective removal of graphene surface modifier through dissolution from the nanohybrid has dramatically improved the electrochemical performance of the material through making the structure more porous. The formation of porous structure after removal of the graphene surface modifier is also evidenced from surface area and porosity measurement. The nanohybrid materials show the best capacitance value of 630 Fg−1 at current density 0.5 A/g with good electrochemical stability. The thermal stability of the coupled hybrid materials is significantly improved than the individual component. This synthesis strategy can also be further applied to fabricate large scale uniform flexible conducting films. The general nature of the synthesis and the resulting nanohybrid materials can offer potential applications like energy storage, electronic device, sensor and EMI shielding... Read More

• Poly(3-hexyl thiophene)-b-poly(N-isopropyl acrylamide): Synthesis and its composition dependent structural, solubility, thermoresponsive, electrochemical, and electronic properties.

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• 19 January 2016 ➧ Journal of Polymer Science, Part A: Polymer Chemistry 2016, 54, 1785–1794. ➧ DOI: https://doi.org/10.1016/j.electacta.2015.12.130
• Conjugated block copolymers consisting of poly(3-hexyl thiophene) (P3HT) and a thermoresponsive polymer poly(N-isopropyl acrylamide) (PNIPAM) with varying composition have been synthesized by facile click reaction between alkyne terminated P3HT and azide terminated PNIPAM. The composition-dependent solubility, thermoresponsive property in water, phase behavior, electrochemical, optical, and electronic properties of the block copolymers were systematically investigated. The block copolymers with higher volume fraction of PNIPAM form thermoresponsive spherical micelles with P3HT-rich crystalline cores and PNIPAM coronas. Both X-ray and atomic force microscopic studies indicated that the blocks copolymers showed well-defined microphase separated nanostructures and the structure depended on the composition of the blocks. The electrochemical study of the block copolymers clearly demonstrated that the extent of charge transport through the block copolymer thin film was similar to P3HT homopolymer without any significant change in the band gap. The block copolymers showed improved or similar charge carrier mobility compared with the pure P3HT depending on the composition of the block copolymer. These P3HT-b-PNIPAM copolymers were interesting for fabrication of optoelectronic devices capable of thermal and moisture sensing as well as for studying the thermoresponsive colloidal structures of semiconductor amphiphilic systems. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1785–1794... Read More