Jaya Bajpai

Water sorption through a semi-interpenetrating polymer network (IPN) with hydrophilic and hydrophobic chains

Abstract Dynamics of water uptake by semi-interpenetrating polymer networks (IPNs) of poly(acrylamide-co-styrene) and poly(vinyl alcohol) were investigated at room temperature (27±0.2°C) and constant pH. The nature of the swelling process of the IPN was investigated in light of the Fickian transport and the effects of varying experimental conditions such as the change in the composition of the IPN, pH and ionic strength of the swelling medium were studied on the swelling kinetics of the IPN. The networks obtained were also characterized by IR spectral analysis and the molecular weight between crosslinks ( M c ) and crosslink density ( q ) of the networks were evaluated.

Controlled pesticide release from biodegradable polymers

Polymers have been widely used in agriculture for applications including controlled release of pesticides and other active ingredients. The ability to predict their delivery helps avoid environmental hazards. Macromolecular matrices used as carriers in controlled release of agricultural active agents, especially pesticides, are reviewed. The review focuses on the advantages and mechanisms of controlled release. It includes biodegradable polymers in agriculture, their manufacturing methods, and their degradation mechanisms and kinetics. The article also presents a critical account of recent release studies and considers upcoming challenges.

Responsive Polymers in Biology and Technology

Modern synthetic polymer chemistry has revolutionized the world of polymer materials. Among macromolecular systems of various chemical and architectural profiles the polymers exhibiting property of responsiveness to external signals have emerged as one of the most promising kind of materials in advanced materials science and owe versatile applications in biology and technology. The internal structural designs of these materials enable them to undergo a large and measurable transition in their physicochemical characteristics upon responding to a minor change in the external environment including experimental conditions. The present article reviews the state-of-the-art of the applications of various stimuli responsive polymers and describes their structure-property relationships. The article provides an account of different aspects of stimuli responsive macromolecular systems that include types of systems responsive to various stimuli such as pH, temperature, electric and magnetic fields, different biomolecules, etc. This review article also presents insights into synthetic strategies of these polymer systems and their major applications in areas such as controlled drug delivery, chromatography, sensors, biotechnology, etc. A brief mention of various challenges ahead and the future scope of this field has also been made.

Release dynamics of tetracycline from a loaded semi-interpenetrating polymeric material of polyvinyl alcohol and poly(acrylamide-co-styrene)

A semi-interpenetrating polymer network (IPN) of polyvinyl alcohol (PVA) and poly(acrylamide-co-styrene) (PAMS) was prepared and its potential for controlled release of tetracycline was assessed. The IPN was characterized by IR spectral analysis and network parameters such as the average molecular weight between crosslinks (M_c), crosslink density (q) and number of elastically effective chains (V_e) were evaluated. The influence of various experimental conditions such as different percent loadings, composition of the IPNs, thickness of the loaded device, pH and nature of the release medium were investigated on the release profiles of the drug. Various kinetic constants such as the diffusional exponent (n), diffusion constant (D) and penetration velocity (v) were evaluated for different release processes and based on the dynamic release data, an analysis of transport mechanisms of tetracycline was made using Ficks equations.

Swelling Controlled Delivery of Antibiotic from a Hydrophilic Macromolecular Matrix with Hydrophobic Moieties

A hydrophilic macromolecular network containing hydrophobic moieties has been prepared by free radical copolymerization of acrylamide and styrene in the presence of poly(vinyl alcohol) (PVA) and its potential as controlled drug delivery carrier was evaluated with tetracycline as a model antibiotic drug. The amount of drug was assayed spectrophotometrically. The network was characterized by optical microscopy, infra-red spectroscopy and structural parameters such as average molecular weight between crosslinks (Mc), crosslink density (q) and number of elastically effective chains (Ve) were evaluated. It was found that with increasing concentration of PVA, ST and MBA in the hydrogel, the release rate initially increases but after definite concentrations of the above components the release rate falls. In the case of AM, release rate constantly decreases with increasing AM concentration in the hydrogel.

Evaluation of poly (vinyl alcohol) based cryogel–zinc oxide nanocomposites for possible applications as wound dressing materials

In this investigation cryogels composed of poly (vinyl alcohol) (PVA) were prepared by repeated freeze thaw method followed by in situ precipitation of zinc oxide nanoparticles within the cryogel networks. Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD), Energy dispersive X-ray spectroscopy (EDX) were used to characterize the nanocomposites. The morphologies of native PVA cryogels and PVA cryogel-ZnO nanocomposites were observed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) techniques. The SEM analysis suggested that cryogels show a well-defined porous morphology whereas TEM micrographs revealed the presence of nearly spherical and well separated zinc oxide nanoparticles with diameter<100nm. XRD results showed all relevant Braggs reflections for crystal structure of zinc oxide nanoparticles. Thermo gravimetric-differential thermal analysis (TG-DTA) was conducted to evaluate thermal stability of the nanocomposites. Mechanical properties of nanocomposites were determined in terms of tensile strength and percent elongation. Biocompatible nature was ascertained by anti-haemolytic activity, bovine serum albumin (blood protein) adsorption and in vitro cytotoxicity tests. The prepared nanocomposites were also investigated for swelling and deswelling behaviours. The results revealed that both the swelling and deswelling process depend on the chemical composition of the nanocomposites, number of freeze-thaw cycles, pH and temperature of the swelling medium. The developed biocompatible PVA cryogel-ZnO nanocomposites were also tested for antibacterial activities against both Gram-negative and Gram-positive bacteria.

Designing Gelatin Nanocarriers as a Swellable System for Controlled Release of Insulin: An In-Vitro Kinetic Study

In the present investigation gelatin nanoparticles have been synthesized and characterized by various techniques like FTIR, scanning electron microscopy, particle size analysis and surface charge measurements. The particles were allowed to swell in phosphate buffer saline (PBS) and the influence of various factors like chemical composition of nanoparticles, pH and temperature of the swelling bath was investigated on the water intake capacity of the gelatin nanoparticles. The particles were loaded with insulin and the release kinetics of insulin was studied in PBS medium under different conditions. The effects of percent loading of drug, chemical composition of nanoparticles and pH, temperature of the release medium were examined on the release profiles of the drug and the possible mechanisms of drug transport were investigated. The chemical stability of the loaded drug (insulin) was also assessed especially under highly acidic conditions of artificial gastric juice.

Designing Polyaniline (PANI) and Polyvinyl Alcohol (PVA) Based Electrically Conductive Nanocomposites: Preparation, Characterization and Blood Compatible Study

Novel electrically conducting and biocompatible composite hydrogel materials comprising of poly (aniline) (PANI) nanoparticles dispersed in a poly (vinyl alcohol) (PVA) – g–poly (acrylic acid) (PAA) matrix were prepared by in situ polymerization of aniline. The prepared ionic hydrogels were evaluated for their water uptake capacity in distilled water. While structural insights into the synthesized polymer was sought by Fourier Transform Infrared (FTIR) spectroscopy and X–Ray Diffraction (XRD) techniques, morphology and dimension of PANI particles embedded into the colored optically semi–transparent polymer films were evaluated by Scanning Electron Microscopy (SEM) analysis and Transmittance Electron Microscopy (TEM) while thermal behavior of composite hydrogel was investigated by Differential Scanning Calorimetry (DSC). Electrical conductivity of composite hydrogels containing different PANI percentage was determined by LCR. Considering the potential of electrically conductive nanocomposites materials in biomedical applications the in vitro blood compatibility of nanocomposites was investigated by employing several in vitro tests.

Designing Swellable Beads of Alginate and Gelatin for Controlled Release of Pesticide (Cypermethrin)

In the present study biopolymeric beads of sodium alginate and gelatin were prepared by employing CaCl2 as a crosslinking agent. A series of such microspheres of different compositions were prepared by varying the amounts of sodium alginate, gelatin and CaCl2 in the feed mixture. The beads were loaded with an insecticide like cypermethrin. The prepared loaded and unloaded beads were characterized by FTIR spectral and Environmental scanning electron microscopy (ESEM) techniques, to gain insight into the molecular structure and morphology of beads, respectively. The swelling experiments were performed for different composition of beads and at varying pH and temperature of the swelling media. The swelling controlled release of insecticide was also investigated for 8 days in bi-distilled water as a release medium. The release experiments were performed under the static and varying experimental conditions and the data obtained were fitted to Ficks equation to evaluate diffusion coefficients of insecticide. The results were further analyzed by Ficks power law equation, and the possible mechanisms of the insecticide release were explored at different experimental conditions. Soil–pot experiments were also performed to demonstrate the applicability of the present controlled release technique to agricultural fields.

Modulation in sorption dynamics of a pH-sensitive interpenetrating polymer network (IPN)

Abstract The water sorption dynamics of a binary interpenetrating polymer network (IPN) composed of polyvinyl alcohol (PVA) and poly(acrylamide‐co‐acrylic acid) was studied gravimetrically. The IPN was characterized by IR spectral analysis and various network parameters such as molecular weight between crosslinks (M c), crosslink density (q) and number of elastically effective chains (V e) were also evaluated. The effects of various parameters such as composition of the IPN, pH, and temperature of the swelling medium and addition of inorganic salts were investigated on the kinetics of the swelling process. The dynamic swelling parameters such as the swelling exponent, diffusion constants and penetration velocity were evaluated and the possible mechanisms of water sorption were evolved on the basis of the swelling exponent (n), diffusion constant (D), and penetration velocity (v). The enthalpy of mixing of the IPN and the solvent (water) was also calculated using the Gibbs–Helmholtz equation.