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PVA hydrogel deformation in response to change in temperature or pH

Kazimierska-Drobny Katarzyna

Bulletin of the Polish Academy of Sciences. Technical Sciences

2021

Vol. 69, nr 2

art. no. e136724

Biocompatibility, biodegradability and non-toxicity are the main attributes of any material to be used in biomedical applications. Among all the potential stimuli, pH, salt and temperature exist naturally in the internal environment of the human body. Hence internal stimuli responsive hydrogels can be exploited for specific drug delivery and tissue replacement. Poly(vinyl alcohol) (PVA) is the world’s largest volume synthetic polymer, produced for its excellent chemical resistance, physical properties and complete biodegradability, which has resulted in broad practical applications. PVA could be considered a suitable host material due to its good thermo-stability, chemical resistance and film-forming ability. It is also an important material because of its large-scale applications. Novel data analysis techniques were developed to analyze the response of PVA to external stimuli, including temperature and/or pH. The presented non-contact method shows that the PVA polymer gel, physically cross-linked by freezing and thawing, shrinks and swells under the influence of temperature, which is a reversible phenomenon. Under the given conditions, such as temperature, pH and mechanical load, the dominant factor affecting the swelling or contraction of the hydrogel is the change in the temperature of the liquid in which the PVA hydrogel sample is immersed.

On the design of biodegradable hydrogels both thermosensitive and pH sensitive

Wang B., Guo Y., Hu G.

Materials Science Poland

2010

Vol. 28, No. 1

207--215

A Pluronic oligo(?-caprolactone) block copolymer has been synthesized by ring opening polymerization of ?-caprolactone monomers in the presence of poly(ethylene oxide)-poly(propylene oxide) -poly(ethylene oxide) triblock copolymers, using stannous octoate as a catalyst, and then the block copolymer was terminated with an acryloyl group. A novel biodegradable pH- and temperature sensitive hydrogel has been fabricated by free radical copolymerization of diacylated macromer-methacrylic acid aqueous solution initiated by a redox initiator. The structures of products were characterized by the Fourier transform infrared spectroscopy. Variations of the equilibrium swelling ratio in various environmental solutions confirmed the pH- and temperature sensitivity of hydrogel, which were affected by the MAA content.