Modulating the water behavior, microstructure, and viscoelasticity of plasma-derived hydrogels by adding silica nanoparticles with tailored chemical and colloidal properties

The viscoelastic properties of hydrogels depend on the tridimensional polymeric structure and the behavior of the liquid confined in their pores. The objective here is to modulate these characteristics in plasma-derived hydrogels by the addition of glycidoxypropyl-silica nanoparticles. These nanoparticles exhibited a hydrodynamic average size between 105.4 − 151.0 nm and surface coverage with (3-Glycidoxypropyl) trimethoxysilane of 0–96 %. The reinforced hydrogels are porous networks with spherical nanoparticles homogeneously distributed into their walls. The silanol groups of silica increase four-fold humidity retention compared with the native hydrogel. This correlates with bound water > 45 % on these reinforced hydrogels, in contrast with 75 % of free water on the native one (calculated from DSC in frozen hydrogels). The humidity stability can be also achieved in the hydrogel prepared with nanoparticles exhibiting 96 % organic coverage. Furthermore, this organic content promotes the microstructure chemical crosslinking, resulting in 3.9 and 1.6 higher Young's modulus compared with native and silica-reinforced hydrogels, respectively. The presence of glycidoxypropyl-silica nanoparticles in reinforced hydrogels modulated its viscoelasticity behavior, decreasing stress relaxation, which was explained using the generalized Maxwell-Wiechert model. In conclusion, novel organic-inorganic hybrid hydrogels based on plasma-derived ones and glycidoxypropyl-silica nanoparticles were developed. These nanoparticles are versatile and allow the production of hydrogels with improved viscoelastic behavior that also exhibits high water retention and morphological stability.