Poly(vinyl alcohol)/sulfonated polyester hydrogels produced by freezing and thawing technique: preparation and characterization

Abstract

Poly(vinyl alcohol) (PVA) hydrogels were obtained by freezing (-22 °C) and thawing (+25 °C) process, resulting in a semi-interpenetrating polymer network (s-IPN) with a sulfonated polyester (PES). The cryo-gels samples were analysed in terms of its water uptake capacity (WU) as a function of pH, temperature and ionic strength. WU of all samples were relatively high, and they showed a reasonable sensitivity to both pH and ionic strength. The pH- and ionic strength dependence is attributed to the dissociation of ionizable groups of PES. The degrees of crystallinity of the cryo-gels, determined by using differential scanning calorimetry (DSC), are lower than pure PVA. Besides, decrease of glass transition temperature (Tg) of the samples when compared with pure PVA was observed. This results are due interactions between PVA and PES, which lead to an increase on the amorphous content of the hydrogels. Our results show that, despite of changes in the microstructure of the hydrogels due the presence of the polyelectrolyte, the cryo-gels reveal a long-term stability

Improving the homogeneity of tissue‐mimicking cryogel phantoms for medical imaging

“…32 Alternative methods of crosslinking include the use of electron beam or γirradiation 33,34 and physical crosslinking through the use of freezing and thawing cycles. [35][36][37][38][39][40][41][42][43] Physical crosslinking not only addresses toxicity issues caused by crosslinking agents, but it also leads to a higher mechanical strength through crystallite formation than chemical or irradiative techniques. The number and stability of the crystallites increase with the in-crease in freezing/thawing cycles.…”

Preparation of Poly(vinyl alcohol)/Chitosan-Blended Hydrogels: Properties, <i>In Vitro</i> Studies and Kinetic Evaluation

“…It is one of the first synthetic polymers to be tested as an artificial cartilage, wound dressing, artificial skin, cardiovascular device and drug vehicle [6]. PVA hydrogels have recently received considerable attention due to their potential application in soft tissue engineering, particularly cartilage replacement [7], and have also provided stability during swelling at human body temperature for long term applications [8]. Cell attachment on PVA hydrogel film is low, however, PVA has high water uptake.…”

Relationships between nanostructure and thermomechanical properties in poly(vinyl alcohol)/montmorillonite nanocomposite with an entrapped polyelectrolyte

“…It is noticeable that the presence of a polyelectrolyte entrapped can result in interesting properties as follows: the environment‐sensitivity observed in polymeric hydrogels under physicochemical changes (pH, temperature, pressure, etc.) can be modified by the presence of a polyelectrolyte entrapped into the polymeric matrix 20–22. However, the incorporation of a polyelectrolyte into a polymeric nanocomposite and the characterization of this kind of system are still few studied.…”