Mechanical properties enhancement of hydrogel using narrow dispersed modified silica particles as cross-linker

Abstract

Hydrogels are widely used in manifold applications but the scope of their applications is often severely limited by their poor mechanical behaviors including low toughness and limited stretchability. Many attempts are carried out together to synthesize hydrogels with improved mechanical properties. However, yet to achieve the facile and universal approach to fabricate hydrogel with desired strength and biocompatibility. Here, we have successfully developed hydrogels with high tensile strength and toughness by reinforcing the network structure of acrylamide with grafted silica nanoparticles as cross-linker. Silica nanoparticles grafted with vinyl end groups using 3-(trimethoxysilyl)propyl methacrylate (MPTS) was used as macro-crosslinker during polymerization reaction of acrylamide in presence of modified silica (MSiO2) to form nanocomposite hydrogel. Three kinds of silica particle with different particle sizes 100nm, 200nm and 300nm were used to prepare MSiO2. The unique nature of synthesized nanocomposite hydrogel which contains both organic and inorganic substances led to their wide-spread applications as they have remarkable stretching, and toughness of ∼ 59,400 J m-2 for the elongation. In addition, all the synthesized hydrogels showed high transparency (above 75%) in the wavelengths of visible region light. The tensile test of stress-strain measurements of 100 nm silica containing hydrogels significantly increased the mechanical performance compare with the other 200 nm, 300 nm silica containing hydrogel. In contrast, the compressive stress-strain measurements did not show any significant change. The polymer chains inside the nanocomposite hydrogel can dissipate energy during applied stress while the chemical cross-links between MSiO2 and polyacrylamide ensure the structural integrity, which could be responsible for the improved mechanical properties of fabricated nanocomposite hydrogel.