Showing papers by "Balbir Singh Kaith published in 2014"

Response surface methodology and optimized synthesis of guar gum-based hydrogels with enhanced swelling capacity

Abstract: Guar gum based hydrogel was optimally synthesized using a response surface methodology (RSM) approach for enhanced swelling capacity. Maximization of the water absorption capacity of the synthesized hydrogel was achieved through sequential experimental design based optimization. A fractional factorial screening (Resolution-IV) approach was used to screen significant process variables for maximization of percentage swelling in phase-1. Studied reaction parameters were: (i) monomer concentration, (ii) initiator concentration, (iii) cross linker concentration, (iv) polymerization time, (v) reaction temperature, (vi) vacuum level, and (vii) pH of reaction mixture. A Pareto chart indicated monomer concentration, pH and initiator concentration as significant process variables which were further optimized using full factorial design (23) in phase-2. RSM based center composite design (CCD) was applied to maximize the percentage swelling for the two most significant variables (pH and initiator concentration) in phase-3. Statistical modeling using ANOVA predicted a near neutral range for pH (∼7.0) and an initiator concentration of 21–23 × 10−6 mol L−1 as optimum operating conditions for maximizing the percentage of swelling (5307%). Hydrogels were found to be highly pH sensitive and should be kept in a narrow range for maximization of percentage swelling. Thus, the sequential experimental design was helpful in achieving two fold increases in percentage swelling in a systematic way. Synthesized super absorbent polymers can be used as effective water-saving materials for horticultural and agricultural applications.

Optimal response surface design of Gum tragacanth-based poly[(acrylic acid)-co-acrylamide] IPN hydrogel for the controlled release of the antihypertensive drug losartan potassium

Abstract: The present study proposes the development and optimization of a new interpenetrating polymer network (IPN), consisting of Gum tragacanth, poly(acrylic acid) (PAA), and poly(acrylamide) (PAAm), for the in situ controlled release of losartan potassium under different pH conditions at 37 °C. Solvent amount and monomer concentration were chosen as the process variables and percentage swelling was taken as the process response. ANOVA model fits were made for the data and gave the cubic model as the best fit, with a predicted R2 = 0.976. The maximum desirability was observed to be 19.63 mL solvent and 3.28 × 10−4 mol L−1 monomer concentration, at which the percentage swelling was found to be 266. Whereas, at 23.7 mL solvent and 6.7 × 10−4 mol L−1 monomer, the percentage swelling was found to be at the minimum (139%). The model was validated at the optimal points for developing devices with the maximum swelling capacity. Drug release through the synthesized matrix was found to show non-fickian behavior at pH 2.0, 7.0, and 9.2, with an increasing trend in gel characteristic constant (k). At each pH medium, the initial diffusion coefficient (DI) was found to be higher than the lateral diffusion coefficient (DL).

A study of the biodegradation behaviour of poly(methacrylic acid/aniline)-grafted gum ghatti by a soil burial method

Abstract: Gum ghatti-based cross-linked hydrogels have been studied for their water absorption, flocculation and biodegradation properties. To date, a lot of research has been focused on gum ghatti-based cross-linked hydrogels; however, the synthesis and characterization of gum ghatti-based conductive biomaterials are relatively less explored. Moreover, the biodegradation and moisture retention studies have not been reported for conductive hydrogels. A gum ghatti-based electrically conductive hydrogel was prepared through a two-step aqueous polymerization. Biodegradation studies of the synthesized hydrogels were conducted using a soil burial test. Interpenetrating network structures showed better degradation efficiency than semi-IPN. The weight loss of semi-IPN and IPN was 66% and 86.6%, respectively, in 60 days. Different stages of degradation were studied using FTIR and SEM techniques. Furthermore, application of hydrogels to improve the water retention properties of different soils was studied for agricultural purposes, and it was found that the IPN hydrogel can improve the moisture retention capacity of soil for cultivation.

Gum ghatti based novel electrically conductive biomaterials: A study of conductivity and surface morphology

Abstract: Gum ghatti-cl-poly(acrylamide-aniline) interpenetrating network (IPN) was synthesized by a two-step aqueous polymerization method, in which aniline monomer was absorbed into the network of gum ghatti-cl-poly(acrylamide) and followed by a polymerization reaction between aniline monomers. Initially, semi-IPN based on acrylamide and gum ghatti was prepared by free-radical copolymerization in aqueous media with optimized process parameters, using N,N!-methylene- bis-acrylamide, as cross-linker and ammonium persulfate, as an initiator system. Optimum reaction conditions affording maximum percentage swelling were: solvent (mL) =12, Acrylamide (AAm) (mol·L -1 ) = 1.971, Ammonium peroxydisulfate (APS) (mol·L -1 ) = 0.131·10 -1 , N,N!-methylene-bis-acrylamide (MBA) (mol·L -1 ) = 0.162·10 -1 , reaction time (min) = 210, temperature (°C) = 100 and pH = 7.0. The resulting IPN was doped with different protonic acids. The effect of the doping has been investigated on the conductivity and surface morphology of the IPN hydrogel. The maximum conductivity was observed with 1.5N HClO4 concentration. The morphological, structural and electrical properties of the candidate polymers were studied using scanning electron micrscopy (SEM), Fourier transform infrared spectroscopy FTIR and two-probe method, respectively.

Synthesis of Gum tragacanth and acrylic acid based hydrogel: its evaluation for controlled release of antiulcerative drug pantoprazole sodium

Abstract: In this work, natural polymer was used as matrix for preparing hydrogel to improve the performance of the material in biomedical sector. Gum tragacanth and acrylic acid [Gt-cl-poly(AA)] based hydrogel was prepared by graft copolymerization of natural Gum tragacanth with acrylic acid using ascorbic acid–potassium persulfate as an initiator and glutaraldehyde as cross-linker. Synthesized hydrogel was evaluated as a device for colon-specific controlled drug delivery. The results indicated that higher drug release was found at pH 9.2 followed by pH 7.0 and 2.0. Non-Fickian diffusion mechanism was exhibited at pH 9.2 and Case II diffusion mechanism was found in the case of pH 2.0 and 7.0.

Synthesis, characterization and evaluation of Gum tragacanth and acrylic acid based hydrogel for sustained calcium chloride release – enhancement of water-holding capacity of soil

Abstract: A novel cross-linked hydrogel has been synthesized through graft copolymerization of acrylic acid onto Gum tragacanth, in the presence of ascorbic acid–potassium persulphate as an initiator. Characterization of the synthesized hydrogel was carried out by thermogravimetric analysis (TGA), differential thermal analysis (DTA), differential thermogravimetric analysis (DTG) and scanning electron microscopy (SEM). The results indicated that 10% (w/w) swelled hydrogel could increase the moisture contents of the clay and sandy loam soil up to 5.35% and 4.49%, respectively. Furthermore, the synthesized material was used as a device for sustained release of calcium chloride for longer time. Such properties of synthesized hydrogel like swelling and water retaining capacity can be exploited in the field of agriculture.

Single Step In Situ Synthesis and Optical Properties of Polyaniline/ZnO Nanocomposites

Abstract: Polyaniline/ZnO nanocomposites were prepared by in situ oxidative polymerization of aniline monomer in the presence of different weight percentages of ZnO nanostructures. The steric stabilizer added to prevent the agglomeration of nanostructures in the polymer matrix was found to affect the final properties of the nanocomposite. ZnO nanostructures of various morphologies and sizes were prepared in the absence and presence of sodium lauryl sulphate (SLS) surfactant under different reaction conditions like in the presence of microwave radiation (microwave oven), under pressure (autoclave), under vacuum (vacuum oven), and at room temperature (ambient condition). The conductivity of these synthesized nanocomposites was evaluated using two-probe method and the effect of concentration of ZnO nanostructures on conductivity was observed. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and UV-visible (UV-VIS) spectroscopy techniques were used to characterize nanocomposites. The optical energy band gap of the nanocomposites was calculated from absorption spectra and ranged between 1.5 and 3.21 eV. The reported values depicted the blue shift in nanocomposites as compared to the band gap energies of synthesized ZnO nanostructures. The present work focuses on the one-step synthesis and potential use of PANI/ZnO nanocomposite in molecular electronics as well as in optical devices.