Synthesis and characterization of chemically cross linked carboxymethyl cellulose/chitosan composite hydrogels

This work focuses on green preparation of composite hydrogels with mechanical and chemical properties that make them suitable for real life applications. Polymorphs of chitosan (α and β) were combined separately with carboxymethyl cellulose to create composite hydrogels that present simultaneously carboxylate, hydroxyl, and amine groups. Citric acid was used to promote chemical crosslink and glycerol was used as plasticizer. Physicochemical, morphological, and thermal characterization of composite hydrogels were carried on by means of swelling study, Fourier Transform Infrared Spectrometry, Differential Scanning Calorimetry, X-ray Powder Diffraction, X-Ray Photoelectron Spectroscopy, Nuclear Magnetic Resonance, Scanning Electron Microscopy, and stereomicroscopy. The swelled hydrogels presented a smooth and homogeneous appearance, with the presence of macropores and elastic behavior. However, once they were dried, the material lost its elasticity and became rigid. In the swelling process, the composite hydrogel with the highest equilibrium swelling rate percentage reached 98% at 24 h. Spectroscopical studies confirm the achievement of chemical and physical crosslinking. The chemical crosslinking consists of the formation of amide and ester bonds promoted by citric acid reaction with chitosan and carboxymethyl cellulose, respectively. In the case of physical crosslinking, confirmation was obtained by the presence of COO- and NH3+ interactions. An average molecular structure of composite hydrogels was proposed.

• Autor principal: Calderón Salas, Luis Alberto (author)
• Formato: bachelorThesis
• Lenguaje: eng
• Publicado: 2021
• Materias: Reticulación química; Compuestos; Hidrogeles; Esponjas; Forma de memoria; Chemical crosslinking; Composites; Hydrogels; Sponges; Memory shape
• Acceso en línea: http://repositorio.yachaytech.edu.ec/handle/123456789/362