Amphiphilic Polyphosphazene-Stabilized High Internal Phase Emulsions toward Porous Polymers with Designed Hydrophilicity and Hydrophobicity for Selective Adsorption of Water and Oil.

Abstract

High internal phase emulsion (HIPE) technology offers a robust approach to fabricating porous polymers with precise morphological control. However, monomers with high water solubility, such as methyl methacrylate (MMA) and hydroxyethyl methacrylate (HEMA), present significant challenges in forming stable water-in-oil HIPEs with the help of conventional surfactants. In this work, a series of amphiphilic polyphosphazenes (PPZs) with hydrophobic fluorine-containing segments and hydrophilic segments were synthesized via nucleophilic substitution reactions between poly(dichlorophosphazene) and various nucleophilic reagents. These PPZs were used to stabilize MMA and MMA-HEMA HIPEs by forming an anchoring layer at the water-oil interface. The resulting HIPEs demonstrated remarkable stability over 24 h with only 1 wt % PPZs. Porous PMMA and copolymers P(MMA-HEMA) with a controllable pore size were successfully synthesized via free radical polymerization. The porous PMMA exhibited excellent hydrophobic-oleophilic properties, achieving a maximum water contact angle of 159.8°. The porous PMMA also shows strong absorption performance to various organic solvents, with a maximum absorption capacity to dichloromethane of 3.9 g/g. Conversely, the porous P(MMA-HEMA) showed hydrophilicity with minimum water contact angles of 23° and a maximum absorption capacity to water of 1.9 g/g. Moreover, the effects of the molecular structures and the dosage of PPZs and the concentration of HEMA in the formulation on the morphologies and properties of the HIPEs and the corresponding porous polymers were comprehensively investigated. These notable performances endow the prepared porous PMMA and its copolymer P(MMA-HEMA) with exceptional potential for advanced applications in the field of adsorption. The developed material demonstrates efficacy in environmental remediation and resource recovery, particularly for capturing halogenated solvents (e.g., dichloromethane) and oxygenated residuals (e.g., ethyl acetate) in printing operations, regeneration of acetone-based semiconductor cleaning solutions, and emergency containment of marine hydrocarbon pollutants.