Radiation synthesis of polymeric hydrogels for swelling-controlled drug release studies

Hydrogels are three-dimensional networks of hydrophilic homopolymers or copolymers generally covalently or ionically crosslinked. They interact with aqueous media by swelling to some equilibrium value by retaining the aqueous media in their structures. This study concerns the investigation of the swelling and the controlled drug release behaviour of hydrogels synthesized via the photopolymerisation process.; Copolymers of varying compositions of 2-hydroxyethyl methacrylate (HEMA) and N-vinyl-2-pyrrolidinone (NVP) were prepared by allowing the monomers to be exposed to ultra violet (UV) radiation in the presence of a photoinitiator (PI), Irgacure 819.; A series of N-hydroxyalkyl maleimides, namely N-hydroxymethyl maleimide (HMMI), 2-hydroxy-N-ethyl maleimide (HEMI), 3-hydroxy-N-propyl maleimide (HPrMI) and 5-hydroxy-N-pentyl maleimide (HPMI) were synthesized and used as acceptor monomers. The acceptor monomers were combined with NVP, which was the electron donor monomer to form the donor/acceptor pairs. Kinetic studies were conducted on these donor/acceptor pairs in the CT complex formation by using the Differential Photocalorimeter (DPC) technique. This technique evaluated their efficiency in polymerisation with respect to the heat released. The kinetics data revealed HPMI-NVP system as the most efficient followed by HMMI-NVP system, then HPrMI-NVP and HEMI-NVP being the least efficient. Glucosamine hydrochloride (HCl) and glucose were used as hydrogen donors. Glucosamine HCl was found to be a more superior hydrogen donor than glucose with its relative efficiency in enhancing the polymerisation rate.; Prior to the synthesis of anionic hydrogels using the PI-free polymerisation technique using acrylic acid (AA) as the acceptor and NVP as the donor, kinetics studies using various mole ratios of these monomers were performed using the DPC technique. The kinetics data reflected that the 1:1 mole ratio of AA:NVP was the most efficient system with the highest exotherm. Hydrogels based on AA and NVP were subsequently synthesized.; The polymeric hydrogels synthesized were evaluated for their potential applications as hydrogels through swelling and drug release experiments conducted at 37°C in aqueous media. Polyelectrolyte hydrogels were evaluated for their swelling and drug release behaviour in varying pH environments. The effect of polymer composition on the drug release and swelling behaviour of the hydrogels were evaluated. (Abstract shortened by UMI.)...