▎ 摘　　要

The present work reports 3D-cross-linked polymer network-based coating onto frac sand prior to the epoxy coating to prepare dual-coated sand proppants with very high-stress resistance. The 3D-cross-linked poly (styrene-methyl methacrylate)/divinyl benzene) (PS-PMMA/DVB) coatings have been successfully prepared by the in-situ one-step bulk polymerization method with AIBN as an initiator at 70 degrees C. The 3D-polymer networks coated sand particles were then added with a mixture of epoxy resin and cure (4:1) along with commercial graphene (CG) and cured at 150 degrees C for 5 min. Interestingly, the roundness and sphericity of the sand particles have been retained even after the dual coating. The elasticity (E), hardness (H), and the fracture toughness (K-c) of the dual coating (PS-PMMA/DVB)-(Epoxy-CG) have been reached a maximum of 7.78 GPa, 0.34 GPa, and 3.22 MPa m(1/2) respectively. The mechanically and thermally reinforced dual-coated sand particles with very high-stress resistance up to 12,000 psi will be successful proppants for hydraulic fracture operations.