Investigation of the effects of orientation on freeze/thawed Polyvinyl alcohol hydrogel properties

• Published in: Materials today communications Vol. 17; pp. 82 - 93
• Main Authors: Chee, Bor Shin, Goetten de Lima, Gabriel, Devine, Declan M., Nugent, Michael J.D.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2018
• Subjects: Caffeine; Drug release kinetics; Freeze-thaw cycle; Hydrogel; Polymer orientation; Polyvinyl alcohol; Freeze-thaw cycle; Drug release kinetics; Polyvinyl alcohol; Hydrogel; Polymer orientation; Caffeine
• ISSN: 2352-4928; 2352-4928
• DOI: 10.1016/j.mtcomm.2018.08.005

[Display omitted] •The increase of F/T cycles and stretching cycles result a stiffer PVA hydrogel.•The mechanical stretching cycles increase the orientations on PVA hydrogel.•The degree of swelling increases with increasing alignment of PVA polymer chains.•The drug delivery system is best fit with Hixson-Crowell drug release model.•The drug release rate increases with increasing surface area of stretched hydrogels. Although hydrogels produced via freeze-thawing (F/T) technique have been thoroughly studied in literature, stretching hydrogels in between freeze-thawing cycles could change its properties for drug delivery systems. The PVA hydrogels and Caffeine-contained PVA hydrogels were created by freezing for 20 min using liquid nitrogen and 4 h thawing at 4 °C. The results revealed that the PVA/CAF hydrogel with two F/T cycles followed by two stretching (S) cycles delivered the best response. Furthermore, this sample had the highest degree of crystallinity and Young’s modulus of 36% and 1462 MPa, respectively, which makes this hydrogel very stiff in comparison to all other samples. Moreover, it fits in the Hixson-Crowell drug release model with the highest drug of releasing rate of 15 min, and the highest swelling degree of 470%. Therefore, the study suggests that the number of F/T cycles and stretching cycles influences the properties of the resulting hydrogels and the caffeine release rate.