Papers by Marwa M El Sayed
Hydrogels are three-dimensional cross-linked stable network insoluble in water, which gives them ... more Hydrogels are three-dimensional cross-linked stable network insoluble in water, which gives them a remarkable capacity to absorb both water and biological fluids. Hydrogel has been synthesized from natural or synthetic polymers and/or monomers, which have made tremendous advancements in many different applications. Composite hydrogel is a type of hydrogel prepared by grafting hydrophilic groups, such as hydroxyl (-OH), carboxylic acid (-COOH), imide (-CONH), sulfonic acid (-SO 3 H), amine (-NH 2), and amide (-CONH 2), into the polymer chain's backbone and adding some additives such as kaolin, zeolite, or even different types of nanoparticles. Whereas the polymeric composite hydrogels exhibit stimuli for different properties such as pH, temperature, or light, which may affect swelling, mechanical properties, and self-healing, which in turn play vital roles in different areas. Hence, numerous efforts have been made to synthesize polymer-based composited hydrogels via physical or chemical crosslinking techniques to enhance their physiochemical, biological, and many other properties. Many researchers are currently paying attention to hydrogels and their applications, including wastewater treatment and purification, medical and biomedical applications, agricultural applications, and many other industrial applications. The aim of this review is to summarize the classification of composite hydrogels based on their chemical and physical crosslinking techniques, in addition to the different polymers and additives used to prepare composite hydrogels. Furthermore, the impact of hydrogel on health and the environment has been discussed. Other significant issues were also presented, including the challenges that face hydrogel production and application, which have been discussed.
Egyptian Journal of Chemistry, 2021
Swelling is one of the distinct properties and a significant parameter in the characterization of... more Swelling is one of the distinct properties and a significant parameter in the characterization of the crosslinked hydrogels. Swelling investigation at different temperatures was conducted for the produced hydrogel of chitosan grafted acrylamide/acrylic acid. Peleg's model is a two parameters model, which can be used to describe the absorption of water or swelling. The data show that the swelling degree increases with temperature until it reaches 60°C, after which it decreases as the temperature rises higher. At RT, 30, 40, 60, and 80 °C, the swelling degree values of 1.4, 1.5,1.4, 2.3 and 0.7 g water/g dry hydrogel were observed after 8 hours. The applied models provided a good agreement with the experimental data with high values of the coefficient of determination (2). The observed F values and the standard error indicate the validity of the proposed model to describe the swelling of hydrogel at different temperatures. The swelling rate and swelling degree can be expressed using a 4 th degree polynomial. It was concluded that the exponential association equation model represents swelling characteristics better than the others.
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Papers by Marwa M El Sayed