Synthesis and characterization of new hydrogels based on biopolymers for different applications

Abstract

The present study involves the extraction of chitosan from shrimp shell by different methods, and preparation of many hydrogels which depend on modification of chitosan by using heterocyclic compounds, then the characterization and evaluation used in different applications. 1. The present study involves the extraction of natural biodegradable and non-toxic chitosan from shrimp shell (Egypt case study) by extraction of chitin, then alkaline deacetylation of chitin with sodium hydroxide solution by different concentrations (35%, 50%, 55%, and 70%) at different period of time. The different extracted chitosan's (Cs1, Cs2, Cs3 and Cs4) were characterized by FTIR spectroscopy, thermal stability, morphology, crystallography, elemental analysis and degree of deacetylation. It was found that: chitosan (Cs2) possesses the highest thermal stability, crystallinity and degree of deacetylation which attributed to the increase of the sodium hydroxide concentration, and its morphology shows crystals on its smooth surface.

This study extended to include the synthesis of some quinoline heterocyclic derivatives to be used in the preparation of the hydrogels which depend on the modified chitosan.

2. Synthesis of carboxylic acids and anhydride compounds: • Preparation of [3-(carboxymethyl)-2-(4-alkylphenyl)-6-alkylquinoline-4-carboxylic acids] (IIIa-f) via the reaction of isatin and isatin derivatives (Ia-c) with β-aroylpropionic acids (IIa-c) under Pfitzinger reaction.

• Preparation of [5-aryl-9-alkyl-1H-pyrano[4,3-c]quinoline-1,3(4H)-diones] (IVa-f) via treatment of [3-(carboxymethyl)-2-aryl-6-alkylquinoline-4-carboxylic acids] (IIIa-f) with acetyl chloride . The chemical structures of the prepared compounds were confirmed by FTIR spectroscopy, HNMR and Mass spectrum.