Kashma Sharma

Synthesis and properties of poly(acrylamide-aniline)-grafted gum ghatti based nanospikes

In this work, we have synthesized poly(acrylamide-aniline)-grafted gum ghatti based crosslinked conducting hydrogel via a two-step synthesis method. The first step involved the microwave assisted synthesis of a semi-interpenetrating polymer network (semi-IPN) based on acrylamide and gum ghatti using N,N′-methylene-bis-acrylamide and ammonium persulfate as a crosslinker-initiator system. The semi-IPN has been observed to exhibit as much as 2183% swelling in aqueous solution. The effect of several variables such as time, solvent, pH, microwave power, crosslinker amount, aniline concentration, initiator concentration and monomer concentration on the swelling capacity was explored. In the final step, polyaniline was entrapped within a semi-IPN (optimized reaction condition) followed by doping with hydrochloric acid, which leads to the formation of conducting IPN. The synthesized hydrogels, as monitored by the swelling behaviour were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and thermogravimetric analysis. Finally, the synthesized crosslinked networks have been used in malachite green (MG) adsorption. The result indicates that IPN of poly(acrylamide-aniline)-grafted gum ghatti are potential candidates for dye removal from water.

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

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.

Evaluation of a conducting interpenetrating network based on gum ghatti-g-poly(acrylic acid-aniline) as a colon-specific delivery system for amoxicillin trihydrate and paracetamol

The objective of the present investigation was to develop colon-specific drug delivery systems for amoxicillin trihydrate and paracetamol using Gum ghatti (Gg) based cross-linked hydrogels. An interpenetrating network (IPN) of electrically active hydrogel based on Gg, poly(acrylic acid) (AA) and polyaniline was synthesized by a two-step aqueous polymerization. The radical copolymerization of Gg and AA was done using N,N′-methylene-bis-acrylamide (MBA) and ammonium persulphate (APS) as a crosslinker-initiator system. Optimum operating conditions for maximizing the percentage swelling were solvent (ml) = 10, AA (mol L−1) = 0.291 × 10−3, APS (mol L−1) = 0.219 × 10−1, MBA (mol L−1) = 0.324 × 10−1, reaction time (min) = 180, temperature (°C) = 60 and pH = 7.0. The synthesized semi-IPN matrix was further grafted with aniline through oxidative-radical copolymerization using APS in acidic media. The resultant cross-linked hydrogels were characterized using X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, ToF-SIMS and electrical conductivity. The maximum conductivity was found to be 2.5 × 10−6 S cm−1 at 1.5 N HCl concentration. The synthesized hydrogels were loaded with amoxicillin trihydrate and paracetamol as model drugs to investigate the release behaviour. Amoxicillin trihydrate follows the surface phenomena and weak bonding interaction whereas paracetamol exhibited chemical interaction with the hydrogel matrices. The release rate of both the drugs through the synthesized hydrogel matrices was found to show Fickian behaviour at each pH. The hydrogel networks showed lower release in acidic and neutral media than in basic media, making them particularly suitable carriers for colon-specific drug delivery.

Gum ghatti-based biodegradable and conductive carriers for colon-specific drug delivery

Conductive superabsorbent hydrogels based on gum ghatti (Gg)/methacrylic acid (MAA)/aniline (ANI) were synthesized by gamma radiations initiated by two-step aqueous polymerization. A cross-linking agent N,N′-methylene-bis-acrylamide was used in the polymerization process, and MAA was graft-copolymerized onto Gg by γ-rays. Influence of preparative conditions (absorbed dose, monomers, solvent, and cross-linker concentrations) on the swelling behavior of cross-linked polymer systems has been investigated. Synthesized superabsorbent hydrogels were characterized using thermogravimetric analysis and swelling studies. In biodegradation study of synthesized hydrogels by composting soil method, Gg-cl-poly(MAA-ipn-ANI) showed better degradation efficiency in comparison to Gg-cl-poly(MAA). Synthesized hydrogels were loaded with amoxicillin trihydrate as a model drug to investigate the release behavior of hydrogels at different pH media. Kinetics studies revealed that synthesized hydrogels exhibit a Fickian diffusion behavior at pH 2.4 and 7.2. However, at pH 9.2, a non-Fickian diffusion behavior was observed which make them very suitable for colon-specific drug delivery applications.

Conducting Polymer Hydrogels and Their Applications

The industrial demand for novel and smart materials as well as the urge for basic understanding has led to a notable improvement in the area of polymer science. Recently, significant consideration has been given to the modifications of biodegradable hydrogels based on natural polymers with conducting polymers (CPs), because this extends a straightforward process to couple the better features of CPs with the highly cross-linked hydrogels. The final hydrogels have been developed to change mainly electrical and structural properties to a larger degree. Herein, we present a comprehensive survey of the existing and current literature on conducting hydrogels based on natural polymers. This chapter also highlights ample of methods used to synthesize conducting hydrogel, properties, and characterization techniques. Conducting hydrogels have been used in the removal of dyes from wastewater, drug delivery, fuel cells, supercapacitors, dye-sensitized solar cells, rechargeable lithium batteries, etc. All these justify the rising interest in both academia and industrial development. In this analysis, an overview of potential applications of these conducting hydrogels and current challenges in the field are discussed; some new and futuristic advances in this captivating area are also provided.

Synthesis, characterization, and anti-microbial activity of superabsorbents based on agar–poly(methacrylic acid-glycine):

In this study, poly(methacrylic acid-glycine)-grafted agar-based hydrogels with optimized process parameters were synthesized via a two-step green-radiation induced grafting process using microwave heating. Poly(methacrylic acid) chains were graft copolymerized onto an agar backbone using ammonium persulfate as a free radical initiator and N,N′-methylene-bis-acrylamide as a cross-linking means using microwave heating. The influence of different reaction parameters was investigated on the percentage swelling behavior of the cross-linked hydrogel networks. The prepared hydrogel networks with optimum percentage swelling were characterized by Fourier transform infrared spectroscopy, time-of-flight secondary ion mass spectrometry, scanning electron microscopy, X-ray diffraction, and thermogravimetric analysis, using agar as a reference. The anti-bacterial activities of the prepared hydrogels against Gram-positive Staphylococcus aureus bacteria and Gram-negative Escherichia coli bacteria were investigated. Staphylococcus aureus was found to be more susceptible to the compounds compared to Escherichia coli. These results indicate that the prepared hydrogels have the potential to be applied as anti-bacterial agents.