Dr. Vivek Mishra

h i g h l i g h t s Application of photo/electrochemical synthesis in carbon dioxide (CO 2) conversion. Eco-friendly production of heterocycles and pharmaceuticals from the photo/electrochemical fixation of CO 2. Detailed mechanistic descriptions on the photo/electrochemical transformation.

Pollution of industrial wastewaters containing dyes is a major concern for health in many countries, calling for advanced remediation techniques. Here, we review dye classification, toxicity, and removal with focus on adsorption using nanomaterials and magnetic nanoparticles. We present isotherm modeling and kinetic studies. We discuss factors controlling dye adsorption, such as pH, dye concentration, adsorbent amount, and temperature. Adsorption using magnetic nanoparticles appear as a simple and cost-effective technique. Removal efficiency increases with adsorbent concentration but declines sharply with increasing pH. Temperature is also highly influencing the removal.

India, as a consequence of rich demography, on an average every year produces 62 million tonnes of municipal solid waste; amidst 9000 tonnes are sanitary wastes including pads and diapers. Nevertheless, mounting up testimonies have established the adversities associated with sanitary waste that plunge unsympathetic impacts on societal hygiene. By accumulating, amalgamating, and processing a current investigation, we have arranged a precise sketch on the harms like immune-toxicity, endocrine effects, and tumor promotion by volatile organic compounds like dioxins surfacing from the waste. Also, sustainable approaches viz. using clay-based incinerators in preventing the spread of detrimental gases and exchanging plastic-based synthetic sanitary products with nature-derived green remedies for the prime citizens of the country-Women & Children, and their future applications to generate circular economy. In this graphical review, we showcased how India holding the hands of green chemistry brought science out of the lab into the daily life, making historical amendments, implementing a green, educated, and healthy society.

A series of thermoresponsive ureido-derivatized polymers were synthesized via atom transfer radical polymerization (ATRP) and a postmodification process. All of the polymers were designed to exhibit an upper critical solution temperature (UCST) in aqueous solution, which was mainly dependent on i) the presence of ureido moieties, ii) the chain length of the side groups, and iii) the degree of quaternization (DQ) on a triazole ring. Side group modification of PHEMA was carried out by DCC coupling with 4-pentynoic acid to prepare PHEMA-alkyne (PHA). 2-Azidoethylurea and 2-azidopropylurea were combined with the PHA backbone via click reaction, resulting in triazole-ring containing ureido-derivatized polymers. Quaternization reactions with methyl iodide were conducted on the triazole ring of each polymer to further control the UCSTs. Results showed that the UCST could be precisely tuned by the level of DQ.

Triazole-containing hydrogels show continuous swelling up to 7 days and provide valuable insights for delivering drugs in a controlled manner through slow and prolonged release. Sustain drug release is due to the gradual disruption of hydrophobic aggregation caused by π–π stacking between triazole ring side chains. These hydrogels exhibit obvious thermal and pH sensitivity, which allows for stimuli-triggered drug release.

A facile and efficient one-pot procedure for the synthesis of ring hydrogenated carbamates from aromaticamine and alkylene carbonate under H2gas pressure has been developed using a heterogeneous catalystsystem comprising ruthenium and alkali metal carbonates. The effects of temperature, H2pressure, cat-alyst (types of loaded metal and their supports), molar ratio of substrate/catalyst, and solvent were alsoinvestigated. Among the alkali metal carbonates, the sodium carbonate was found as best promoter fornucleophilic attack and ring-opening (NARO) reaction and thus increased the yield of ring hydrogenatedcarbamate up to 88% when using Ru/C as ring hydrogenation (RH) catalyst. This catalyst system could bereused at least five times without significant loss of activity, which makes this process cost-effective andeco-friendly.

Free radical polymerization is one of the most widely employed polymerization techniques. This technique is applied to prepare latexes to be used in paints, highmolecular weight poly (methyl methacrylate) for safety glass (Plexiglas®
), or foamed poly (styrene) to be applied in coffee cups. Some advantages of radical polymerizations,with respect to other techniques, are the relative insensitivity to impurities, the moderate reaction temperatures and the multiple polymerization processes available, e.g., bulk,solution, precipitation or emulsion polymerization. Some disadvantages related to the mechanism of free radical polymerization is the poor control of the molecular weight and the molecular weight distribution, and the difficulty (or even impossibility) of preparing well-defined copolymers or polymers with a predetermined functionality.To overcome these disadvantages new techniques were developed based on either reversible deactivation of polymer radicals or a degenerative transfer process, called‘living’ or controlled radical polymerizations (CRP). It will be worthwhile to discuss the significance of the living radical polymerization process because of which it was selected for the present investigation. Controlled radical polymerizations, like atom transfer radical polymerizations (ATRP), reversible addition-fragmentation chain transferpolymerization (RAFT), and nitroxide-mediated polymerizations (NMP) represent key strategies for the preparation of polymers with narrow molecular weight distributions. To understand the living radical polymerization, firstly it is important to outline the significant of polymers.

RAFT polymerization of N-vinyl pyrrolidone (NVP) has been investigated in the presence of chain transfer agent (CTA), i.e., prop-2-ynyl morpholine-4-carbodithioate (PMDC). The influence of reaction parameters such as monomer concentration [NVP], molar ratio of [CTA]/[AIBN, i.e., 2,2′-azobis (2-methylpropionitrile)] and [NVP]/[CTA], and temperature have been studied with regard to time and conversion limit. This study evidences the parameters leading to an excellent control of molecular weight and molar mass dispersity. NVP has been polymerized by maintaining molar ratio [NVP]: [PMDC]: [AIBN] = 100 : 1 : 0.2. Kinetics of the reaction was strongly influenced by both temperature and [CTA]/[AIBN] ratio and to a lesser extent by monomer concentration. The activation energy (Ea = 31.02 kJ mol−1) and enthalpy of activation (ΔH‡= 28.29 kJ mol−1) was in a good agreement to each other. The negative entropy of activation (ΔS‡ = −210.16 J mol-1K-1) shows that the movement of reactants are highly restricted at transition state during polymerization. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Glucose based five arms atom transfer radical polymerization initiator was synthesized. This initiator was used to synthesize 5-arms star polymer of N-vinyl pyrrolidone (NVP) through controlled radical polymerization. The ratio of reactantswerekept as 1:1:2:200(initiator:Cu(I)Br:bpy:NVP). The rate of reaction with
respect to NVP was found to be first order, and number-average molecular weight increases linearly with temperature up to 90 ◦C. The activation energy (Ea = 29.75 kJ mol−1) and enthalpy (H‡ = 26.73 kJ mol−1) were found to be in a good agreement with each other for activated complex, and negative value of entropy of activation (S‡ =−219.12 J mol−1 K−1) supports the highly ordered transition state.

The thermal degradation of graft copolymers of both polysaccharides (guar gum and xanthan gum) showed gradual decrease in mass loss. Pure guar gum degraded about 95% but pure xanthan gum degraded about 76% up to 1173.15 K, while graft copolymers of guar gum and xanthan gum degraded only 65–76% up to 1173.15 K. Acrylic acid grafted guar gum and xanthan gum showing two-step degradation with formation of anhydride and ketonic linkage during heating, same pattern of degradation was found for xanthan gum-g-methacrylic acid. Guar gum-g-acrylamide degraded in single step and xanthan gum-g-acrylamide started to degrade above 448.15 K and it is a two-stage process and imparts thermal stability due to the formation of imide linkage with evolution NH3. Guar gum-g-methacrylamide degraded in three steps due to the loss of NH3 and CO2 successively. 4-vinyl pyridine grafted both polysaccharides show single step degradation due to loss of pyridine pendent. N-vinyl formamide grafted guar gum and xanthan gum started to degrade at about 427.15 K, showed two-stage degradation process with the evolution of CO and NH3 molecules while guar gum-g-(N-vinyl-2-pyrrolidone) degraded into two steps by the loss of pyrrolidone nucleus. Gum-g-2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) showed two-step degradation processes in two successive degradation steps, while xanthan gum-g-AMPS has started degradation at about 427.15 K and completed in five degradation steps. Overall, it was found that the grafted polysaccharides are thermally more stable than pure polysaccharides.

The modification of Carboxymethylcellulose (CMC) through vinyl monomers containing different functional groups to increase its functionality has attracted the attention of researchers. Among the various methods for modifying polymers, graft copolymerization appears to be highly attractive and has made a paramount contribution towards improved industrial and biomedical applications. In recent years, the polymer functionalization of CMC has greatly benefited from advances in polymerization techniques. Graft copolymerization technique provides different functionalities onto CMC surface, where CMC and its modified graft copolymers have multifunctional characteristics and known for their potentially wider range of applications. In addition to the conventional grafting techniques, we highlight the recent developments in graft copolymerization process that allows increase control over the grafting and permits the production of functional cellulose which possess improved physical and chemical properties.

Poly(acrylamide) (PACM) used in this study was prepared through an effective atom transfer radical polymerization process and characterized by NMR, FTIR, and thermo gravimetric analysis. Resulting polymer was used for the uptake of heavy metal ions from aqueous solution. Partition coefficient, retention capacity, and metal ion uptake behavior in aqueous solution of PACM at different monomer percent conversions and effect of parameters for optimization of polymerization reaction gives thermally stable PACM. Efficiency of metal ion uptake of different molecular weights of PACM were tested in batches for Ni2+, Pb2+, Cu2+, Zn2+, and Hg2+ ions in single metal solution. Metal ion sorption capacities increase with increase in polymer concentration. Metal ion sorption capacities in single metal system were 6.3 mg g−1 Ni2+, 6.0 mg g−1 Pb2+, 6.9 mg g−1 Cu2+, 6.2 mg g−1 Zn2+, 22.4 mg g−1 Hg2+ for PACM of 88% conversion (Mn = 19,850). Uptake by the PACM indicates that they are effective in removing metal ions from single metal ion solutions. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2012

A novel polymer bearing coumarin pendants of 4-allyloxy-2H-chromen-2-one (ACO) was synthesized by atom transfer radical polymerization (ATRP) in toluene at 110°C using 2-Bromoisobutyryl bromide (BIBB), Cu (I) Br, and 2,2′-bipyridyl (bpy) as initiator, catalyst, and ligand, respectively. The most appropriate molar concentration ratio of [ACO] : [BIBB] : [Cu (I) Br] : [bpy] was found to be 40 : 1 : 1 : 2 for controlled polymerization. Successful chain extension polymerization of poly (4-allyloxy-2H-chromen-2-one) (PACO) confirms the livingness of the process. The activation energy (Ea) (76.26 kJ mol−1) and enthalpy of activation (ΔH‡) (73.07 kJ mol−1) were in good agreement to each other proving the feasibility of the reaction and negative value of entropy of activation (ΔS‡) (−320 J mol−1 K−1) supported the highly restricted movement of reacting species in transition state during polymerization. Initial polymer decomposition temperature of PACO was found to be 130°C. SEM analysis revealed that polymer surface is not smooth with pointed rod like shapes. The polymer/Ag nanocomposite was synthesized and examined in view of antibacterial effect against Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Proteus mirabilis, and Klebsiella pneumonae. PACO and its Ag nanocomposite (PACON) have been found to be active selectively against bacterial pathogen E. fecalis with minimum inhibitory concentration of 50 and 32 μg mL−1, respectively. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

This book gives a good understanding of the progress being made in controlled radical polymerization process. The basic principle of controlled/living radical polymerization is fundamental to the creation of new radical polymerization techniques including atom transfer radical, and reversible addition-fragmentation transfer polymerization. These discoveries bring new life to the field of free radical polymerization; indeed, an abundance of polymer materials with different topologies have been prepared. I hope that this Special Topic on “Functional Controlled/Living Radical Polymers: Synthesis, Kinetics and Physico-chemical Properties” will cultivate new ideas and catalyze discoveries in every reader’s laboratory. This book is aimed to provide information related to the newest controlled radical polymerization methodology, ATRP and RAFT, their required components and their advantages and necessities. I demonstrates that how simple molecule selectively arrange as different topology like linear, star, multi arm polymers containing functional groups for various applications.