An agro-waste origin cardanol benzoxazine monomer (Ca) has shown potential as a suitable sustainable linker to chemically bind petroleum industry generated waste, elemental sulphur (S) to form random copolymers poly(S-r-Ca). A series of random copolymers with varied weight percent of elemental sulphur (20–95\%) were synthesised via bulk polymerisation methodology. The Ca monomer offered several reaction sites to facilitate the formation of sulphur rich copolymers as supported by FT-IR, 1H NMR, Raman spectroscopy, XRD, DSC and TGA studies. The curing temperature of Ca was found to be lowered to reaction temperature i.e. 185 °C from 242 °C using elemental sulphur as co-reactant. Preliminary studies of random poly(S-r-Ca) copolymers with a very high sulphur loadings (&gt;80\% w/w) demonstrated inverse vulcanisation and suggest their utility as an efficient substitute to elemental sulphur as a cathode material in Li-S battery. © 2016 Elsevier Ltd

Bimlesh Lochab

Chemistry

(SoNS) School of Natural Sciences

Shukla S.

Ghosh A.

Roy P.K.

Mitra S.

<p>Shiv Nadar University is a comprehensive, multidisciplinary, research-focused, and student-centric University offering a full range of academic programs at the undergraduate, postgraduate and doctoral level. With state-of-the-art infrastructure, the University comprises of academic wings, sophisticated labs, international standard sports facilities, amphitheaters, auditorium, conference rooms and smart classrooms. The University&rsquo;s goal is to become internationally recognized for the quality of its research and creative endeavors and their applicability to improving quality of life, generating new insights and expanding the boundaries of human knowledge creativity. Committed to excellence in teaching, research and service, the University aims to serve the higher education needs of India and the world beyond.</p>

Shiv Nadar University

Polymer

Lithium-sulfur (Li–S) batteries are among the most promising candidates for the next-generation rechargeable batteries due to their high energy density, cost-effectiveness, environmental friendliness and being on the verge of commercialization. However, considering the cathode part, low conductivity of sulfur, large volume expansion, dissolution of polysulfides in the electrolyte and their unfavorable shuttle behavior lead to low cell capacity and poor cycle life. More importantly, the high flammability of sulfur causes safety concerns that might hinder the large-scale application of lithium-sulfur batteries in electric vehicles, especially in tropical countries. Herein, we report a covalently linked sulfur (~83\% w/w) flame retarding sustainable copolymer as a suitable and safe cathode material for the practical application of Li–S batteries in tropical region. A remarkable intrinsic flame-retardant property with appreciable specific capacity and excellent capacity retention provide an alternative strategy for designing cathode materials for safe and sustainable Li–S batteries. © 2020

Energy Storage Materials

Halogen-free flame-retardant sulfur copolymers with stable Li–S battery performance

Polybenzoxazines are evolving as a new class of phenolic resins with a tremendous amount of applications. The ease of structural designing, synthetic procedure, and polymerization reactions are attractive to affect their properties ensuing as an effective substitute for many existing polymers. The nonrenewable origin, toxicity, and increasing cost of petro-based raw materials are alarming issues. Therefore, the emergence of sustainable benzoxazines, especially based on naturally abundant, agro-waste origin cardanol is encouraging as it allows both solventless synthesis of monomers and processing to form highly thermally stable thermoset resins. The inherent functionalities in cardanol benzoxazine provide a platform for further structural modifications to advance their applications as adhesives, composites, and energy storage devices. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Macromolecular Chemistry and Physics

Cardanol Benzoxazines: A Versatile Monomer with Advancing Applications

Despite recent advances in polybenzoxazines (PBzs), especially of sustainable origin, the lowering of the curing temperature still remains a challenge in addressing their exploration in low-temperature processing applications. Innovative iron-based catalysts which are naturally abundant, cost-effective, and with larger surface area could demonstrate a practical, economic and facile approach for the development of iron NPs-polybenzoxazine composites. Here we propose an approach to develop a composite based on smartly-capped iron nanoparticles (NPs) and agro-waste phenolic-sourced cardanol benzoxazine monomer as a one-step solution with the benefits of lowering the curing temperature and providing superparamagnetism. NPs are smartly designed with a variation in the nature of the functionality in the capping agent and are characterized by thermogravimetry analysis (TGA), Fourier transform infrared (FTIR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The NPs showed a spherical shape of ∼10 nm in size with appreciable magnetic characteristics. Both iron ions and available functionalities in the capping agent endow benefits in lowering the curing temperature of cardanol benzoxazine (64 °C), and enhancing its maximum thermal stability (34 °C), as determined by differential scanning calorimetry (DSC) and TGA, respectively. In addition, the nature of the chemical linkages in the polybenzoxazine network and the initial growth in the molecular weight of the polymer were found to be influenced by iron NPs, as supported by FTIR, nuclear magnetic resonance (1H-NMR), UV-visible (UV-vis) spectroscopy, and gel permeation chromatography (GPC). The capping-agent-facilitated NPs distribution in the polybenzoxazine matrix was determined by atomic force microscopy (AFM). Polymer nanocomposites even with a 5 wt\% loading of NPs showed good magnetic saturation and superparamagnetic behavior. The present work demonstrated a one-step solution with the incorporation of NPs in a benzoxazine monomer accounting for modification in the properties of polybenzoxazine composites with the benefits of magnetism. © 2018 The Royal Society of Chemistry.

Fulltext

Journal of Materials Chemistry A

Sustainable one-step strategy towards low temperature curable superparamagnetic composite based on smartly designed iron nanoparticles and cardanol benzoxazine

High-energy electrochemical storage containing earth abundant materials could be a choice for future battery development. Recent research reports indicated the possibility of room-temperature sodium-ion-sulfur chemistry for large storage including smart grids. Here, we report a room-temperature sodium-sulfur battery cathode that will address the native downsides of a sodium-sulfur battery, such as polysulfide shuttling and low electrical conductivity of elemental sulfur. In this Letter, we use a sustainable route which ensures a large sulfur confinement (i.e., ∼90 wt \%) in the cathode structure. The sulfur-embedded polymer is realized via thermal ring-opening polymerization of benzoxazine in the presence of elemental sulfur (CS90) and later composite with reduced graphene oxide (rGO). The resulting CS90 allows a homogeneous distribution of sulfur due to in situ formation of the polymer backbone and allows maximum utilization of sulfur. This unique electrode structure bestows CS90-rGO with an excellent Coulombic efficiency (99\%) and healthy cycle life. © 2017 American Chemical Society.

ACS Energy Letters

Sulfur Copolymer: A New Cathode Structure for Room-Temperature Sodium-Sulfur Batteries

Cardanol, a sustainable origin phenol, was utilized as a reactive diluent to mediate solventless Mannich-type condensation reaction with para-formaldehyde and primary aromatic amines to form a homologous series of benzoxazine (Bz) monomers namely C-a, C-ddm, C-trisapm and C-tetraapm which differ in their degree of oxazine functionality as mono-, di-, tri- and tetra-oxazine respectively. A strong correlation is reflected between the number of oxazine rings in the monomer and the polymerization behavior, thermo-mechanical transitions, and properties of the polybenzoxazine synthesized. The monomer structure was confirmed by FTIR, 1H-, 13C-NMR spectroscopy and mass spectrometry. The curing, rheological, thermo-mechanical and thermal properties were determined using DSC, FTIR, rheometer, DMTA, LSS and TGA studies. The curing characteristic due to ROP of Bz monomers was supported both by DSC and FTIR studies. The presence of neighboring oxazine group in monomers (C-a to C-tetraapm) strongly attenuates the curing temperature (Ti = 225-140°C), enhances Tg, thermal stability, and mechanical properties. Interestingly, DFT calculations also supported the lowest curing temperature for highest oxazine functionality monomer (C-tetraapm). The interplay between the degree of oxazine functionality in the monomer; extent of H-bonding and crosslink density values in sustainable origin synthesized polybenzoxazines is suggested. The thermoset showed an increasing trend (PC-a < PC-ddm < PC-trisapm < PC-tetraapm) in Tg (58-109°C), thermal stability (355-391°C), char yield (13-37\%), LOI (23-31) and storage modulus (3.6-66.5 MPa) values. The monomers are liquid to semi-viscous paste at room temperature and showed potential for solventless processing in adhesive applications. © 2015 Royal Society of Chemistry.

RSC Advances

Cardanol benzoxazines-interplay of oxazine functionality (mono to tetra) and properties

Exploration of sustainable alternatives to chemicals derived from petro-based industries is the current challenge for maintaining the balance between the needs of a changing world while preserving nature. The major source for sustainable chemicals is either the natural existing plant sources or waste generated from agro-based industries. The utility of such resources will supplement new processed materials with different sets of properties and environmental friendliness due to their biodegradability and low toxicity during preparation, usage and disposal. Amongst other polymers used on a day-to-day basis, phenolic resins account for vast usage. Replacement of petro-based monomers such as phenol and its derivatives either partly or completely utilized for the synthesis of such resins is ongoing. Extraction of natural phenolic components from cashew nut shell liquid, lignin, tannin, palm oil, coconut shell tar or from agricultural and industrial waste, and their utilization as synthons for the preparation of bio-based polymers and properties obtained are reviewed in this paper. This review article is designed to acknowledge efforts of researchers towards the "3C" motto-not only trying to create but also adapting the principles to conserve and care for a sustainable environment. This review paper describes how extraction, separation and recovery of desired phenolic compounds have occurred recently; how substituted phenol compounds, unmodified and modified, act as monomers for polymerization; and how the presence of sustainable phenolic material affects the properties of polymers. There are about 600 references cited and still there is a lot to uncover in this research area. This journal is © the Partner Organisations 2014.

Naturally occurring phenolic sources: Monomers and polymers

MRS Communications

Structural origins of enhanced capacity retention in novel copolymerized sulfur-based composite cathodes for high-energy density Li–S batteries

ACS Macro Letters

Improving the Charge Conductance of Elemental Sulfur via Tandem Inverse Vulcanization and Electropolymerization

Angewandte Chemie International Edition

Inside Cover: Thiophene-Based, Radial π-Conjugation: Synthesis, Structure, and Photophysical Properties of Cyclo-1,4-phenylene-2′,5′-thienylenes (Angew. Chem. Int. Ed. 1/2015)