Search

Biopolymer chitosan (CS), chitosan grafted acrylamide based titanium dioxide (CS-g-PAM/TiO 2 ) and magnetite (CS-g-PAM/Fe 3 O 4 ) hybrid nanocomposites have been synthesized through free radical graft co-polymerization and successfully validated as corrosion inhibitors for mild steel in 15 % HCl solution. The synthesized compounds have been characterized through FTIR, APC, XRD and TEM. The thermal stability of the nanocomposites was established by TGA. The anticorrosive performance was determined through gravimetric measurements and by electrochemical study. According to EIS technique it was observed that CS-g-PAM/TiO 2 and CS-g-PAM/Fe 3 O 4 showed maximum 97.19 % and 95.49 % efficiency respectively. Langmuir adsorption isotherm is obeyed in each case. The activation and adsorption parameters have been determined from isotherm study. FESEM and AFM confirmed better adsorption layer formed by composites over mild steel surface. The elemental composition of the metal samples was proved by the XPS investigation. DFT and ANOVA test further corroborates the experimental results., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

This work demonstrates a facile pathway to develop a biopolymer based amphiphilic macromolecule through reversible addition-fragmentation chain transfer (RAFT) polymerization, using dextran (a biopolymer) as starting material. Also, a new hydrophobic monomer [2-methyl-acrylic acid 1-benzyl-1H-[1,2,3] triazol-4-ylmethyl ester (MABTE)] has been synthesized using methacrylic acid via "click" approach. The resultant copolymer displays controlled radical polymerization characteristics: narrow polydispersity (Ð) and controlled molecular weight as obtained through advanced polymer chromatography (APC) analysis. In aqueous solution, the copolymer can proficiently be self-assembled to provide micellar structure, which has been evidenced from field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analyses. The in-vitro cytotoxicity study illustrates the nontoxic nature of the copolymer up to 100 μg/mL polymer concentration. The copolymer has been found to be worthy as an efficient carrier for the sustained release of hydrophobic drug: Indomethacin (IND)., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Herein, a new hybrid nanocomposite, comprising of titania nanoparticles (TiO 2 NPs) and carbon dots (CDs) deposited polyvinyl imidazole crosslinked chitosan [cl-Ch-p(VI)/TiO 2 NPs-CDs] has been developed. The nanocomposite has been synthesised by in-situ deposition of TiO 2 NPs and CDs onto the surface of the copolymer under microwave irradiation. To the best of our knowledge, this in-situ approach has effectively been applied for the first time to fabricate green fluorescent CDs from sugar cane juice at moderate temperature (75 °C) under microwave irradiation. The developed nanocomposite has been characterized using UV-Vis spectroscopy, 13 C NMR, XRD, HR-TEM, STEM and XPS analyses. The results suggest that the successful deposition of TiO 2 NPs and CDs onto the surface of crosslinked chitosan is achieved. The experimental studies indicate that the NPs/CDs-impregnated nanocomposite allows efficient photocatalytic degradation of toxic organic compounds (~98.6% degradation of 2,4-dicholorophenol, ~95.8% degradation of Reactive Blue 4, ~98.2% degradation of Reactive Red 15) in the presence of sunlight. Finally, LC-MS analysis of the resultant degraded materials reveals the formation of organic molecules with lower molecular mass., (Copyright © 2020 Elsevier B.V. All rights reserved.)

A novel nanocomposite (cl-Ch-pMAc@ZnO/CdSQDs) has been developed under microwave irradiation via fabrication of ZnO/CdS quantum dots on anionically functionalized chitosan [i.e. poly (methacrylic acid) crosslinked chitosan (cl-Ch-pMAc) in the presence of diethylene glycol dimethacrylate (DEGDMA) crosslinker]. The structural, morphological and chemical/physical properties of crosslinked chitosan and the nanocomposites have been investigated using 13 C nuclear magnetic resonance spectroscopy ( 13 C NMR spectroscopy), high resolution-transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) analyses. The nanocomposite demonstrates outstanding efficacy towards the photocatalytic degradation of cationic dyes [malachite green (MG), and safranin (SF)] and toxic organic molecule 2,4-dichloro phenol (2,4-DCP) under the exposure of sunlight. Liquid chromatography mass spectroscopy (LC-MS) studies predict that small molecules are produced by degradation. Moreover, the composite exhibits excellent antibacterial activity towards E-coli and B. subtilis. Finally, the nanocomposite can be regenerated effectively with changing the solution pH and also shows 5 times reusability without significant reduction on its efficiency., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Herein, a novel binary graft copolymeric flocculant [St-g-(PAAm-co-PMETAC)] has been developed using starch, polyacrylamide (PAAm) and poly (2-methacryloyloxy ethyl trimethyl ammonium chloride) (PMETAC). The copolymer has been synthesised by grafting of PAAm and PMETAC chains on starch backbone using free radical polymerization. FTIR and 1 H NMR spectral analyses have been used for structural confirmation of developed copolymer. Determination of molecular weight reveals that after grafting of PAAm and PMETAC on starch, the molecular weight as well as radius of gyration have been increased as compared to pristine starch. The surface morphologies of starch and St-g-(PAAm-co-PMETAC) have been assessed by FESEM analysis. TGA/DTG along with MS analyser is able to track the pre-specified compounds over the entire period of degradation temperature. The synthesised graft copolymer i.e. St-g-(PAAm-co-PMETAC) demonstrates brilliant efficiency as flocculant towards the treatment of blast furnace effluent generated in integrated steel plant., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Dextrin and poly (N-vinyl caprolactam) based amphiphilic graft copolymer has recently been developed using RAFT polymerization. The prepared graft copolymer has been characterized in details using FTIR and 1 H NMR spectral analyses, GPC, TGA, FESEM, TEM and DLS analyses. GPC analysis results indicate that the polymerization is controlled, while the LCST value of the copolymer suggests that the synthesized copolymer demonstrates sol-gel behaviour on applying temperature. FESEM and TEM analyses envisage that the graft copolymer has spherical morphology with nanoscale dimension. DLS study reveals that the micellar size vary with change of pH and temperature, demonstrating the dual-responsive behaviour of the graft copolymer. Finally, the developed graft copolymer shows worthy efficacy towards the pH and thermo-responsive release of encapsulated pyrene in sustained manner., (Copyright © 2018 Elsevier B.V. All rights reserved.)

A novel nanocomposite derived from cationically modified guar gum and in-situ incorporated SiO2 NP (cat-GG/SiO2) has been developed. The cat-GG has been synthesised by grafting poly(2-(diethylamino)ethyl methacrylate) on GG backbone. Various analyses endorse the suitability of cat-GG as well-organized template for the development of homogeneous SiO2 NPs. Dye adsorption studies predict that cat-GG/SiO2 efficiently and selectively adsorb anionic dyes (reactive blue-RB and Congo red-CR) from mixture of dye solutions. This is because of high surface area, multifunctional chelating H-bonding interactions and electrostatic interactions of cationic adsorbent with anionic dyes. Dyes adsorbed on the composite surface are desorbed reversibly using pH 10 stripping solution. Besides, cat-GG/SiO2 has been recycled efficiently with no prominent loss of dye uptake capacity, even after 4 adsorption-desorption cycles., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The synthesis and characterization of a novel biodegradable graft copolymer based on partially hydrolyzed polymethylacrylate (PMA) grafted amylopectin (AP) was reported which was developed for the synthesis of silver nanoparticles from silver nitrate solution by facile green technique. The prepared graft copolymer was biodegradable which was shown by fungal growth. Characterization of silver nanoparticles was carried out by UV-VIS spectroscopy (417nm), HR-TEM, SAED and FESEM analysis. The TEM findings revealed that the silver nanoparticles are crystalline and globular shaped with average particle size ranging from 11 to 15nm. The synthesized silver nanoparticles exhibit excellent antibacterial sensitivity towards both Gram negative and Gram positive bacteria namely Vibrio parahaemolyticus (ATCC-17802) and Bacillus cereus (ATCC-14579) respectively and were also shown a good catalytic activity towards 4-nitrophenol reduction., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Chitosan fibers were prepared in citric acid bath, pH 7.4 and NaOH solution at pH 13, to form ionotropically cross-linked and uncross-linked fibers, respectively. The fibers formed in citric acid bath were further cross-linked via carbodiimide chemistry; wherein the pendant carboxyl moieties of citric acid were used for new amide bond formation. Moreover, upon covalent cross-linking in the ionically gelled citrate-chitosan fibers, incomplete conversion of the ion pairs to amide linkages took place resulting in the formation of a dual network structure. The dual cross-linked fibers displayed improved mechanical property, higher stability against enzymatic degradation, hydrophobicity and superior bio-mineralization compared to the uncross-linked and native citrate cross-linked fibers. Additionally, upon cyclic loading, the ion pairs in the dual cross-linked fibers dissociated by dissipating energy and reformed during the relaxation period. The twin property of elasticity and energy dissipation mechanism makes the dual cross-linked fiber unique under dynamic mechanical conditions. The differences in the physico-chemical characteristics were reflected in protein adsorption, which in turn influenced the cellular activities on the fibers. Compared to the uncross-linked and ionotropically cross-linked fibers, the dual cross-linked fibers demonstrated higher proliferation and osteogenic differentiation of the MSCs in vitro as well as better osseous tissue regeneration in a rabbit model., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Herein, we report the application of an efficient polymeric flocculant based on amylopectin grafted with poly (acrylic acid) (g-AP) for the treatment of synthetic effluent as well as various industrial wastewaters. The flocculation characteristics of g-AP have been explored in different pH conditions using silica suspension by measurement of residual turbidity as well as floc size. Results suggest that in acidic pH, patching mechanism is predominating while at neutral and alkaline pH, bridging is the main mechanism. In addition, aggregation of particles and particle collision models confirm that bridging mechanism is the key mechanism at alkaline condition. Further, g-AP demonstrates excellent potential as flocculant for the treatment of paper effluent, textile wastewater and shows better flocculation performance than that of commercially available flocculant. Besides, the pilot scale study of mine processwater suggests excellent efficacy of g-AP as flocculant., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Hydroxypropyl methyl cellulose has been modified by grafting synthetic polyacrylamide chains [g-HPMC (M)] in presence of microwave irradiation, which has used as carrier for controlled release of 5-amino salicylic acid (5-ASA). The FTIR and UV-vis-NIR studies reveal the excellent compatibility between g-HPMC (M) and 5-ASA. Field emission scanning electron microscopy (FESEM) and UV-vis-NIR analyses suggest that physical interaction predominates between the drug and matrix. % equilibrium swelling ratio (% ESR) of g-HPMC (M) decreased with addition of salt solutions and follow the order: Na(+)>K(+)>Mg(2+)>Ca(2+)>Al(3+). The in vitro 5-ASA release studies indicate that g-HPMC (M) delivers the drug preferentially in colonic region in more sustained way than that of HPMC. The 5-ASA release follows first order kinetics and non-Fickian diffusion mechanism. These favorable features make the graft copolymer a potential matrix for colon specific delivery of 5-ASA., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Herein, we report an oral route administration for ciprofloxacin hydrochloride delivery using dextrin and poly (2-hydroxyethyl methylacrylate) based crosslinked hydrogel (c-Dxt/pHEMA). Various characteristics such as FTIR spectra, XRD analyses, UV-VIS-NIR spectra, FESEM and E-SEM analyses, rheological characteristics, gel kinetics, deswelling characteristics as well as biodegradation study of the hydrogel have been carried out. FTIR, XRD along with solid state UV-VIS-NIR analyses explain the good compatibility between the drug and the hydrogel matrix. The in vitro release study demonstrates that c-Dxt/pHEMA releases ciprofloxacin in a sustained way (33.75% of drug has been released in 18h) and is expected to be a promising matrix for ciprofloxacin carrier. The release kinetics and mechanism suggest that drug release follows first order kinetics and non-Fickian diffusion mechanism. Finally, the hydrogel shows excellent physical stability as carrier for ciprofloxacin up to 3 months., (Copyright © 2014 Elsevier B.V. All rights reserved.)

In the present study, hydroxypropyl methyl cellulose grafted with polyacrylamide (HPMC-g-PAM) hydrogel was evaluated in vitro as a potential carrier for controlled release of 5-amino salicylic acid (5-ASA). The graft copolymer was developed by grafting PAM chains onto HPMC backbone using potassium persulphate as initiator. The swelling behaviour of hydrogel based tablet was investigated as a function of pH and time in various buffer solutions similar to that of gastric and intestinal fluids. The % equilibrium swelling was found to be higher in case of simulated intestinal fluid (pH=7.4) and lower in simulated gastric fluid (pH=1.2), making an ideal matrix as required for colon specific drug delivery. The drug release study was performed at various pH values akin to the condition of GI tract. The release kinetics of 5-ASA showed non-Fickian diffusion behaviour. This indicates that the release is controlled by a combination of polymer relaxation or erosion of the matrix and diffusion of the drug from the swollen matrix., (Copyright © 2013 Elsevier B.V. All rights reserved.)

pH dependent hydrogels of modified tamarind kernel polysaccharide (TKP) were synthesized by grafting with polyacrylamide chains on TKP backbone in presence of microwave irradiation and initiator. The present study is carried out to design oral controlled drug delivery systems for aspirin using synthesized hydrogels as carrier in form of tablets. TKP-g-PAM based hydrogels show significant enhancement for control release of aspirin. Release behavior of aspirin has been evaluated using USP type I apparatus in 900 mL of buffer solutions (pH 1.2, 6.8, 7.4), maintained at 37°C at 100 rpm. It is observed that with increase in percentage of grafting (% G), swelling of matrices increases whereas erosion and rate of drug release decrease. The effect of % G onto t50 value (time taken for release of 50% drug) has also been discussed. The release characteristics from the matrices under study show non-Fickian diffusion mechanism, suggesting the controlled release of aspirin., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Novel carboxymethyl guar gum (CMG)-chemically modified multiwalled carbon nanotube (MCNT) hybrid hydrogels were synthesized at different MCNT levels as potential device for sustained trans-dermal release of diclofenac sodium. Spectroscopy together with morphology, thermogravimetry, and rheological studies proved relatively strong CMG-MCNT interaction at 0.5 and 1 wt% levels of MCNT whereas de-wetting was increased with higher MCNT concentration. Drug encapsulation tendency increased with addition of MCNT; maximum entrapment was noticed at 1 wt% MCNT level. Hydrogels containing 0.5, 1 and 3 wt% MCNT exhibited slower trans-dermal release than neat CMG due to slightly higher gel viscosity and more drug entrapment. Slowest but steady release was obtained from 1 wt% MCNT loaded hydrogel due to highest viscous resistance among all other hybrid nanocomposites., (Copyright © 2011 Elsevier B.V. All rights reserved.)

A novel hybrid nanocomposite has been prepared using in situ incorporation of nano-sized filler (silica) onto carboxymethyl tamarind kernel polysaccharide (CMT). Various characterizations were employed to confirm that silica nano particles have been incorporated onto the polymer matrix. Rheological characteristics reveal stronger CMT-Si interaction at 0.5 and 1 wt% level. Beyond 1 wt% Si concentration, the interaction is less and so there is little drop in shear viscosity. Flocculation efficiency increases with incorporation of nano filler, maximum efficacy being observed at 1 wt% silica concentration. All the nanocomposites exhibited better flocculation characteristics in comparison to pure CMT., (Copyright © 2011 Elsevier B.V. All rights reserved.)

A novel polymeric flocculant based on polyacrylamide grafted carboxymethyl guar gum (CMG-g-PAM) has been synthesised by grafting polyacrylamide chains onto CMG backbone using conventional redox grafting and microwave assisted grafting methods. Under optimum grafting conditions, 82% and 96% grafting efficiencies have been observed in case of conventional and microwave assisted methods respectively. The optimum sample has been characterized using viscometry, spectroscopic analysis, elemental analysis, molecular weight and radius of gyration determination. The flocculation characteristics of grafted and ungrafted polysaccharides have been evaluated in kaolin suspension, municipal sewage wastewater and decolourization efficiency of a dye solution (methylene blue). It is evident from results that CMG-g-PAM synthesised by microwave assisted grafting method is showing best flocculation characteristics., (Copyright © 2011 Elsevier B.V. All rights reserved.)

An efficient polymeric flocculant was synthesized by microwave assisted grafting of polyacrylamide to dextrin. By varying the reaction conditions, various grades of graft copolymers were synthesized to obtain the optimized one. Viscometry, elemental analysis, FTIR spectroscopy, (13)C NMR spectroscopy, determination of molecular weight and radius of gyration using SLS analysis, thermal analysis and SEM analysis were employed to confirm that polyacrylamide has been grafted onto the dextrin backbone. The flocculation efficiency of the grafted products in kaolin suspension was dependent on the molecular weight, radius of gyration and length of the grafted polyacrylamide chains. The flocculant obtained by microwave assisted grafting method was superior to dextrin and polyacrylamide-based commercial flocculant (Rishfloc 226 LV) in flocculation tests., (Copyright © 2010 Elsevier B.V. All rights reserved.)

This paper details the study of applicability of microwave initiated synthesized polyacrylamide grafted guar gum (GG-g-PAM) as matrix for controlled release of 5-amino salicylic acid (a drug used for the treatment of ulcerative colitis). In vitro release of this drug from various grades of GG-g-PAM has been studied by USP dissolution method (paddle type). The effect of percentage grafting on the rate of drug release has been investigated. The power of the microwave oven and other factors being kept constant, the percentage grafting in turn is dependent on the net time of exposure to microwave irradiation; thus a correlation can be drawn between net time of irradiation and rate of drug release (from the matrix). This holds the promise of a tailor-made matrix, with the rate of drug release being precisely programmed at the molecular level. Further, the drug release study was carried out in different pH medium, to investigate the possibility of pH triggered release for colon targeted drug delivery (where the pH is alkaline)., (Copyright 2010 Elsevier B.V. All rights reserved.)

Synthesis of cationic tamarind kernel polysaccharide (Cat TKP), its detailed physicochemical characterization and application as an efficient flocculant for the treatment of textile industry wastewater have been investigated. N-3-Chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTAC) was used as a cationic reagent to introduce quaternary amine groups onto the backbone of tamarind kernel polysaccharide (TKP). Various grades were synthesized to obtain the optimized one. Effect of reaction parameters onto the degree of cationization has also been investigated. The synthesized polymers were characterized by various macromolecular characterization techniques, which confirm that cationization does take place. Afterwards, the applicability of TKP and various grades of Cat TKP's as flocculants for the treatment of textile industry wastewater was investigated. The flocculation experiments showed that TKP alone contributes little to the flocculation. However, cationic TKP led to significant improvement as flocculant for the treatment of textile industry wastewater. The best performing Cat TKP (i.e. Cat TKP 3) was thereafter compared with a commercial flocculant, which is cationic in nature. It has been observed that Cat TKP 3 surpasses the flocculation efficiency over commercial flocculant.

This paper reports the investigation of microwave initiated synthesized polyacrylamide grafted carboxymethylstarch (CMS-g-PAM) as matrix for sustained drug release. 'In vitro' release of a model drug (5-amino salicylic acid) from CMS-g-PAM matrix has been studied. It is evident that higher the percentage grafting, more sustained is the rate of drug release. Further, the percentage grafting vs. t(50) value (i.e. time taken for release of 50% of the enclosed drug) correlation has been successfully studied for the first time. This correlation will lead to the possibility of a programmable drug release matrix based on grafted polysaccharide. In this matrix, the rate of release of the enclosed drug can be precisely programmed simply by adjustment of percentage grafting during synthesis.