Preparation of hydrophobic and h igh‐strength polymer microspheres based on constructing a “Functional monomer‐St‐DVB ” copolymer structure: Ultra‐low‐density proppants

Ultra‐low‐density proppants are of great significant in slick water fracturing system, but the polymer composite microspheres can hardly promise the quality of oil and gas due to their poor hydrophobicity. To address the issue, we prepared several types of modified styrene‐divinyl benzene copolymer microspheres (MSDBs) with long‐term durable hydrophobicity and high strength, including O‐MSDBs (hydrophobic MSDBs), LO‐MSDBs (long‐time hydrophobic MSDBs), and CO‐MSDBs (coated O‐MSDBs) on the basis of a molecular structure of “KH570‐styrene (St)‐divinyl benzene (DVB)” copolymer. In this article, the design concept and the structure of MSDBs was clarified, and performances of MSDBs are systematically discussed and compared with commercially available hydrophobic microspheres. The O‐MSDBs, a kind of nanoparticle patterned St‐DVB copolymer microspheres, were prepared by a one‐step suspension polymerization undergoing a sol–gel process, showing strong hydrophobicity with a water contact angle up to 140.7°, but short durability in strong hydrochloric acid or hydrofluoric acid; On the contrary, LO‐MSDBs perform better in the stability and durability of hydrophobicity with a slightly lower water contact angle about 135.9°. The LO‐MSDBs were designed by coating functionalized St‐DVB copolymer microspheres with fluororesin. Similarly, CO‐MSDBs from fluororesin‐coated O‐MSDBs were designed. As expected, CO‐MSDBs have a stronger hydrophobicity (139.0°) than LO‐MSDBs and longer durability than O‐MSDBs. Moreover, the MSDBs exhibit better properties than the commercially available hydrophobic polymer and ceramic microspheres.