Shape memory behaviour of polyvinyl alcohol aerogels cross-linked with Fe3+ & Cu2+ metallic ions

Abstract

Abstract The utter purpose of this study was to embed metal ions in polymer chains to improve the shape memory behaviour of polyvinyl alcohol (PVA) aerogels in which metal ions were used as cross-linking agents for PVA. PVA–Cu and PVA–Fe hydrogels were first prepared by adding different amounts of Cu (NO3)2.3H2O and Fe (NO3)3.9H2O salts, respectively, then aerogel samples were prepared by the freeze-drying of hydrogels. Fourier transform infrared test was employed to evaluate the chemical structure. Gravimetric and mercury porosimetry methods were performed to characterize the porosity of aerogels. Field emission scanning electron microscopy examined the microstructure of the network and the porosity of the aerogels. The shape memory behaviour of the nanocomposite aerogels was evaluated by dynamic-mechanical analysis. The test results showed that by adding 25 wt% copper salt and 40 wt% iron salt to the PVA, the maximum gel fractions were achieved. Compared to pure PVA, the recovery ratios of nanocomposite aerogels increased by about 80% and 140% and their moduli increased by more than 370% and 300%, respectively.