Poly(acrylic acid)/palygorskite microgel via radical polymerization in aqueous phase for reinforcing poly(vinyl alcohol) hydrogel

Poly(acrylic acid)/palygorskite microgel (PAA/Pal) with three-dimensional network structure was synthesized in the aqueous phase by conventional free radical polymerization. The functionalized Pal (f-Pal) acted as the multiple cross-linker in the polymerization system. The composition, structure, and morphology of the microgels were characterized by FT-IR, XRD, TGA and SEM. The microgel was introduced into the poly(vinyl alcohol) solution (PVA) to prepare the PAA/Pal microgel reinforced PVA hydrogel. During the evaporation-swelling (E-S) process, the OH and COOH in microgel form a new cross-linked network through the synergistic hydrogen bonding with the OH in PVA. The tensile strength of hydrogels increased from 1.46 MPa to 2.71 MPa, and the elastic modulus increased from 233 kPa to 756 kPa with the addition of microgels. The hydrogel in the study had excellent mechanical strength and recovery properties, and was expected to be used in tissue engineering and soft machines. •PAA/Pal microgel was synthesized via conventional free radical polymerization in the aqueous phase.•The mechanical strength and tensile modulus of hydrogels can be increased by 85.6% and 224.4%, respectively.•The mGel/PVA hydrogel was reinforced by the newly formed synergistic hydrogen bonds.