Physical Gelation of Poly(Vinyl Alcohol) Solutions by Freeze-Thawing: Role of Process Parameters on Chemical and Mechanical Properties of Hydrogels

Hydrogels are hydrophilic polymer networks dispersed in water and reinforced by physical or chemical interactions. Their exceptional ability to absorb and retain large amounts of water supports their use in the medical and pharmaceutical sectors, where biocompatibility is an essential requirement. This property also makes them promising for space applications, especially for radiation protection, where their high hydrogen content plays a key role in mitigating the effects of ionizing radiation on astronauts and electronic equipment. In this work, physically cross-linked hydrogels are prepared using a poly(vinyl alcohol) (PVA) matrix, varying the freeze-thaw cycles and sonication times of the polymer solution. Analyses performed included chemical composition determined by Fourier transform infrared spectroscopy (FTIR), thermo-mechanical properties evaluated by dynamic mechanical analysis (DMA), water content, density and degree of crystallinity. The results obtained were used to study how the mechanical and chemical properties of the hydrogel vary with different preparation conditions.