Composite hydrogels composed of polymer networks with silica (SiO2) nanoparticles were studied as model systems for use in high performance concrete. These highly swellable networks in aqueous environments allow for more water to be available internally as the curing reaction of concrete proceeds. The hydrogels are synthesized from inverse suspension polymerization to create chemically crosslinked poly(acrylic acid) (PAA) and poly(acrylamide) (PAM) spherical particles. SiO2 nanoparticles are introduced in the reaction as either an unmodified colloidal dispersion or functionalized to react into the polymer network. Hydrogel copolymer composition was varied from majority PAA to majority PAM and SiO2 loading levels ranged from 0-10 wt. % of monomer feed. Particle size analysis from optical microscopy indicated the gel particle diameters ranged from 50-100 microns in the dry particle state. Gravimetric swelling of the gels in pure water showed that incorporation of SiO2 into the networks decreased the swelling and that the SiO2 could be acting as additional crosslinking sites. Swelling performance at various pH and salt concentrations was further investigated. Thermogravimetric analysis was used to quantify the level of SiO2 inclusion into the gel networks. Interactions among PAA, PAM, surfactant, and SiO2 were studied using zeta potential experiments to understand the effects of possible molecular adsorption onto nanoparticles.

Synthesis and characterization of composite hydrogel networks for use in high performance concrete

255th National Meeting (2018)

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