Role of Interfacial Tension of Solvating Diluents and Hydrophilic–Hydrophobic Cross-Linkers in Hyper-Cross-Linked Solid Supports

Abstract

The properties of a hyper-cross-linked solid support are the outcome of the interfacial tension created by solvating/nonsolvating diluents, the hydrophilicity/hydrophobicity of the cross-linkers, and their concentrations. Interestingly, a more hydrophobic diluent and cross-linker as well as a higher concentration of cross-linker-containing copolymer revealed an increase in surface area. A high surface area and low cross-link density (CLD) polymer illustrated higher epoxy content. Importantly, maximum surface area (533 m2/g) was obtained at high CLD; inversely, epoxy content (1.83 mmol/g) was higher at low CLD polymer. Notably, greater rigidity of cross-linker and its higher concentration increased Tmax and Tg; contrarily, greater flexibility of cross-linker and its concentration attenuated Tmax and Tg. Thermal study demonstrated the thermostability (300 °C) and polymer safe temperature (220 °C). Indeed, a lower solubility parameter difference between polymer and swelling solvent produces a higher polymer–solvent interaction parameter, resulting in increased polymer swelling. Polymers with high surface area and low CLD demonstrated greater swelling behavior.