How are highly stretchable silica/polyacrylamide (PAM) nanocomposite hydrogels synthesized?

Highly stretchable silica/polyacrylamide (PAM) nanocomposite hydrogels were synthesized via in situ free radical polymerization in the presence of silica nanoparticles. The effect of particle size and content of silica nanoparticles on tensile properties and swelling behavior were investigated.

What is the tensile strength of silica/Pam hydrogels?

The tensile strength of silica/PAM hydrogels is 2 times that of PAM gels, and the elongation at break is nearly 2800% when the silica particle size is 15 nm and the content is 10 wt%. This excellent stretching property of hydrogels was ascribed to the presence of hydrogen bond between PAM molecule and silica nanoparticles.

Can silica nanoparticles form hydrogen bond with polymer chains of hydrogels?

A large number of hydroxyl groups on the surface of silica nanoparticles can form hydrogen bond with polymer chains of hydrogels [ 28, 29 ]. Herein, we designed and synthesized the silica nanocomposite hydrogels (SiO 2 -NC gel) cross-linked by hydrogen bond between unmodified silica nanoparticles and polyacrylamide molecular chains.

Do silica nanoparticles affect tensile properties and swelling behavior?

The effect of particle size and content of silica nanoparticles on tensile properties and swelling behavior were investigated. The hydrogen bond between PAM molecule and silica nanoparticles was evidenced by Fourier transform infrared spectroscopy and the swelling behavior of hydrogels.

What is the hydrogen bond between Pam molecule and silica nanoparticles?

The hydrogen bond between PAM molecule and silica nanoparticles was evidenced by Fourier transform infrared spectroscopy and the swelling behavior of hydrogels. The tensile strength of silica/PAM hydrogels is 2 times that of PAM gels, and the elongation at break is nearly 2800% when the silica particle size is 15 nm and the content is 10 wt%.

How does silica content affect hydrogel tensile strength and elongation?

Under silica content of higher than 10%, the silica nanoparticles tend to agglomerate, resulting in a decrease in the homogeneity of hydrogels, and resultantly a decrease of tensile strength and elongation at break. For S110-NC hydrogels (Fig. 8c and d ), the tensile properties were improved with the increasing of the silica nanoparticles content.