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|Type:||Artigo de periódico|
|Title:||Water absorption profile of PAAm-co-PNIPAAm/chitosan hydrogel with sandwich-like morphology|
|Abstract:||Thermo-sensitive hydrogels of chitosan ( CS) networks sandwiched by poly( N-isopropylacrylamide) ( PNIPAAm) and poly( acrylamide) ( PAAm) were prepared. The formation of chitosan networks inside the gel was done by immersing the PAAm-co-PNIPAAm/ CS mixture in a 1.5% glutaraldehyde aqueous solution. The water uptake ( WU) and water absorption mechanism of PAAm-co-PNIPAAm/ CS were studied in following conditions: 25 and 37 degrees C, swelling pHs of 3.80 and 7.01, and cross- linking times of CS in glutaraldehyde of 2 and 40 min. The characterization of the PAAm-co-PNIPAAm/ CS was done by scanning electron microscopy ( SEM), infrared analysis ( FT-IR), and thermogravimetric analysis ( TGA). Pore size was larger at pH 25 degrees C than at pH 37 degrees C. Increase in CS content, crosslinking time, temperature, and swelling pH lead to a decrease in the sensitivity of the hydrogel to water. The chitosan networks improved the mechanical properties of the hydrogel. On the other hand, the hydrophilichydrophobic groups present in PNIPAAm are responsible for a low thermosensitivity observed in the swelling studies at different temperatures. The water transport mechanism throughout hydrogels was evaluated by kinetic behavior using Fickian and non- Fickian diffusion, and Case II transport. The PAAm-co-PNIPAAm/ CS obtained is not pH-sensitive; however, they may be used to remove either proteins or other chemicals from aqueous solutions.|
|Editor:||European Polymer Federation|
|Citation:||E-polymers. European Polymer Federation, 2007.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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