Papers by Keyword: IPN Hydrogel

Abstract: Various hydrogels such as polyvinyl alcohol (PVA) and poly (2-hydroxyethyl methacrylate) were assessed as articular cartilage replacement in the past. In the current study, the biphasic, biocompatible, and mechanically tunable Polyacrylamide-Alginate (PAAm-Alg) hybrid hydrogel was evaluated with different parameters such as load, speed and lubrication to study friction and wear performance of the material. Dried mass loss of hydrogel with lubrication was in the range of 2-9 wt %. The average friction coefficient of hydrogel under bovine serum lubrication was measured as 0.03, which is fairly close to native cartilage tissue. SEM studies revealed adhesion as the dominant wear mechanism due to excessive plastic deformation, independent of load and speed condition while fatigue wear mechanism was more noticeable under 1.3MPa applied pressure. However, the lubrication has dramatically decreased the wear rate and as a result, it was difficult to distinguish the worn surface of hydrogel samples from the unworn surface and just a light depression was observed on the samples, which is promising for load-bearing applications such as cartilage replacement.

Abstract: Novel hydrogels based on natural rubber latex (NRL) and rice starch (RSt) (1:2 ratio) were prepared with various amount of N,N-methylenebisacrylamide (MBA) and 2.5 phr of maleic acid to form interpenetrating networks (IPN) using free-radical polymerization technique. The thermal and mechanical properties were performed by differential scanning calorimetry and mechanical tests. From data obtained, the change in Tg of rubber and melting point of RSt indicated that polymer-polymer interaction could be formed in IPN hydrogel. The higher amount addition of MBA created more mechanical strength of IPN hydrogels caused by the higher of interlacement formation. However, their mechanical strength of such hydrogels was lower than that of NRL alone due to the formation of amorphous structure in IPN hydrogel. These IPN hydrogels also improved the swelling property which will be utilized for wound healing application.

Abstract: P(AA-co-DMAA) superporous drug-loaded hydrogels containing berberine hydrochloride were prepared by dispersion polymerization in foam system with acrylic acid (AA) and N,N-dimethyl acrylamide (DMAA) as monomers. Then sodium alginate (SA) as the second network was added to the system, and P(AA-co-DMAA)/SA interpenetrating polymer network (IPN) hydrogels were formed. The effects of pH value, reaction time between SA and glutaric dialdehyde (GA), the concentration of SA and GA on release behavior of berberine hydrochloride were discussed. The FT-IR spectra showed that P(AA-co-DMAA)/SA IPN hydrogels were synthesized successfully. The inverted fluorescence micrograph of P(AA-co-DMAA)/SA showed that some part of the superporous structures were still retained.The cumulative release profiles showed that the release rates were slightly higher in pH=6.8 phosphate buffer solution (PBS) than the one in pH=1 HCl solution. The release rate was the slowest in distilled water, only 7.3% within 24h. When the reaction time between SA and GA was shortened, the release speed of berberine hydrochloride became faster. The pore size of P(AA-co-DMAA) hydrogels was reduced with the concentration of SA and GA increased, and the release rate decreased due to the more dense network structures.