Ramanujam Brahmadesam Thoopul Srinivasa Raghava

Dr. Ramanujam Brahmadesam Thoopul Srinivasa Raghava


Research Focus & Metrics

Academic Career Length

13Years (2014-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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19 December 2023 in ACS Omega
Verified
Journal Article
Open access
RHReshma Haridass
Reshma Haridass
ASAleena Sabu
Aleena Sabu
NANikhitha Augustin
Nikhitha Augustin
Pratheep Kumar AnnamalaiPratheep Kumar Annamalai
Pratheep Kumar Annamalai
RRRamanujam Brahmadesam Thoopul Srinivasa Raghava
Ramanujam Brahmadesam Thoopul Srinivasa Raghava
Polyvinylidene fluoride (PVDF)-expanded graphite (ExGr) nanocomposites have been prepared by solution blending and melt processing methods. In the presence of polyvinylpyrrolidone (PVP), enhanced dispersion of graphite nanosheets (GNSs) in the PVDF matrix, as suggested by field emission scanning electron microscopy analysis, results in very low electrical percolation threshold (0.3 wt % ExGr). X-ray diffraction, Fourier transform infrared spectroscopy, and differential scanning calorimetry (DSC) analyses confirm the coexistence of electroactive gamma and nonpolar alpha phases. Wrapping of PVP chains around GNSs reduces the crystallinity in PVDF-ExGr nanocomposites in comparison to that in neat PVDF films, as evidenced by DSC analysis. Thermogravimetric analysis confirms enhanced thermal stability of PVDF-ExGr nanocomposites above 500 °C mainly attributed to the PVP-assisted dispersion of GNSs. The water contact angle of solution-blended PVDF-ExGr nanocomposite films increases with and without PVP in comparison to that of the neat PVDF film. Compression-molded PVDF-ExGr nanocomposites also exhibit electroactive gamma and nonpolar alpha phases of PVDF with reduction in electrical conductivity compared to solvent-cast films.

31 March 2020 in Polymer Bulletin
Verified
Journal Article
Closed access
PDF file
RRRamanujam Brahmadesam Thoopul Srinivasa Raghava
Ramanujam Brahmadesam Thoopul Srinivasa Raghava
PAParag V. Adhyapak
Parag V. Adhyapak
SRS. Radhakrishnan
S. Radhakrishnan
RMR. Marimuthu
R. Marimuthu

3 March 2025 in Electrochem
Verified
Journal Article
Open access
PDF file
KSKanya K S
Kanya K S
TRT. Rajagopalan
T. Rajagopalan
RRRamanujam Brahmadesam Thoopul Srinivasa Raghava
Ramanujam Brahmadesam Thoopul Srinivasa Raghava
Sodium-ion batteries (SIBs) have garnered significant attention as a cost-effective and sustainable alternative to lithium-ion batteries (LIBs) due to the abundance and eco-friendly extraction of sodium. Despite the larger ionic radius and heavier mass of sodium ions, SIBs are ideal for large-scale applications, such as grid energy storage and electric vehicles, where cost and resource availability outweigh the constraints of size and weight. A critical component in SIBs is the electrolyte, which governs specific capacity, energy density, and battery lifespan by enabling ion transport between electrodes. Among various electrolytes, composite polymer electrolytes (CPEs) stand out for their non-leakage and non-flammable nature and tunable physicochemical properties. The incorporation of NASICON (Na Super Ionic CONductor) fillers into polymer matrices has shown transformative potential in enhancing SIB performance. NASICON fillers improve ionic conductivity by forming continuous ion conduction pathways and reduce polymer matrix crystallinity, thereby facilitating higher sodium-ion mobility. Additionally, these fillers enhance the mechanical properties and electrochemical performance of CPEs. Hence, this review focuses on the pivotal roles of NASICON fillers in optimizing the properties of CPEs, including ionic conductivity, structural integrity, and electrochemical stability. The mechanisms underlying sodium-ion transport facilitated by NASICON fillers in CPE will be explored, with emphasis on the influence of filler morphology and composition on electrochemical properties. By scrutinizing the recent findings, this review underscores the potential of NASICON-based composite polymer electrolytes as appropriate material for the development of advanced sodium-ion batteries.

4 September 2025 in Nanoscale
Verified
Journal Article
Closed access
PDF file
ASAleena Sabu
Aleena Sabu
PUPooja U.
Pooja U.
MNMeera B. Nair
Meera B. Nair
DSDinesh K. Shukla
Dinesh K. Shukla
RPRajkumar Patel
Rajkumar Patel
RRRamanujam Brahmadesam Thoopul Srinivasa Raghava
Ramanujam Brahmadesam Thoopul Srinivasa Raghava
This study demonstrates the influence of morphologies of zinc oxide on the electrical, EMI shielding, piezoelectric, and triboelectric properties of PVDF-based hybrid nanocomposites.

27 March 2024 in Journal of Thermoplastic Composite Materials
Verified
Journal Article
Closed access
NANikhitha Augustin
Nikhitha Augustin
PMPranesh Muraliharan
Pranesh Muraliharan
ASAleena Sabu
Aleena Sabu
KSKanya Koothanatham Senthilkumar
Kanya Koothanatham Senthilkumar
Pratheep Kumar AnnamalaiPratheep Kumar Annamalai
Pratheep Kumar Annamalai
RRRamanujam Brahmadesam Thoopul Srinivasa Raghava
Ramanujam Brahmadesam Thoopul Srinivasa Raghava
Poly(vinylidene fluoride) (PVDF) based conducting polymer composites with carbon nanomaterials can be used for mechanical energy harvesting through piezoelectric or triboelectric effect. This study aims to investigate the influence of PMMA molecular weight on the electrical, thermal, and wetting properties of PVDF/40 wt.% PMMA blend nanocomposites reinforced with expanded graphite (ExGr). The blend nanocomposites with 40 wt.% PMMA have been prepared by solution blending method by using two different molecular weights of PMMA whose melt flow indices are 2 g/10 min and 2.3 g/10 min. The coexistence of the electroactive gamma and non-polar alpha phases of PVDF in the blend nanocomposites has been confirmed by X-ray diffraction, Fourier transform infrared spectroscopy and differential scanning calorimetry analyses. While overall crystallinity (%) of low molecular weight PMMA employed blend nanocomposites is lower than that of high molecular weight PMMA blended nanocomposites, the electroactive gamma phase has been found to increase in the former blend nanocomposites. The dispersion of graphite nanosheets has been observed to be better in high molecular weight PMMA employed blend nanocomposites which results in higher electrical conductivity. Impedance analysis of PVDF-40 wt.% PMMA-2 wt.% ExGr blend nanocomposite with high molecular weight PMMA results in enhanced interjunction capacitance (74.5 pF) in comparison to low molecular weight PMMA mixed blend nanocomposites (68 pF). Water contact angle (WCA) increases with molecular weight of PMMA and ExGr loading level. Thermogravimetric analysis has shown that the char content (above 500°C) is slightly higher for the blend with low molecular weight PMMA than with high molecular weight PMMA.

21 October 2025 in Macromolecular Materials and Engineering
Verified
Journal Article
Open access
DJDaphne Mary John
Daphne Mary John
Pratheep Kumar AnnamalaiPratheep Kumar Annamalai
Pratheep Kumar Annamalai
AHAlireza Hosseinmardi
Alireza Hosseinmardi
SMSreekanth Kaduvallil Mahadeva
Sreekanth Kaduvallil Mahadeva
KRKothandaraman Ramanujam
Kothandaraman Ramanujam
Ashok Kumar NanjundanAshok Kumar Nanjundan
Ashok Kumar Nanjundan
Piezoelectric materials convert mechanical energy into electrical energy and are used as sensors, actuators, and energy harvesters in Industry 4.0. Polymer nanocomposites with adjustable performance and affordability could transform piezoelectric technology. Fluoropolymers like poly(vinylidene fluoride) (PVDF) and its copolymers are common in developing these composites with various nanoparticles. Zinc oxide (ZnO) is promising due to its non‐centrosymmetric structure, high piezoelectric coefficient, and versatile nanostructure synthesis. This review covers recent trends in fabricating and optimizing piezoelectric polymer nanocomposites based on fluoropolymers and ZnO, including synthesis principles and advanced methods. It examines approaches to enhance piezoelectric and physical properties, emphasizing PVDF/ZnO composites' applications. The review also discusses challenges and future directions, serving as a resource for researchers and industry professionals aiming to improve piezoelectric materials for next‐generation use.