Degradable Polymer-Based Oil–Water Separation Materials Prepared by High Internal Phase Emulsion Templating Method and Silica-Modification

The development of oil-water separation materials that combine high separation efficiency, robust mechanical properties, and environmental degradability remains a significant challenge. This study presents a novel degradable and superhydrophobic porous material fabricated via a multi-step process. A porous foam was first synthesized from degradable poly(ε-caprolactone-co-2-ethylhexyl acrylate) using a high internal phase emulsion templating technique. The foam was subsequently modified through in situ silica (SiO₂) deposition via a sol-gel process, followed by grafting with hydrophobic hexadecyltrimethoxysilane (HDTMS) to produce the final oil-water separation porous materials. Various characterization results showed that the optimized material featured a hierarchical pore structure in micro scales and the porosity of the foam remained ~90% even after the 2-step modification. Mechanical tests indicate that the modified material exhibited significantly enhanced compressive strength and the water contact angle measurements revealed a superhydrophobic surface with a value of approximately 156°. The prepared material demonstrated excellent oil/water separation performance with notable absorption capacities ranging from 4.11 to 4.90 g/g for oils with different viscosity. Additionally, the porous material exhibited exceptional cyclic stability, maintaining over 90% absorption capacity after 10 absorption-desorption cycles. Moreover, the prepared material achieved a mass loss of approximately 30% within the first 3 days under alkaline hydrolysis conditions (pH 12, 25 °C), which further escalated to ~70% degradation within four weeks. The current work establishes a feasible strategy for developing sustainable, high-performance oil-water separation materials through rational structural design and surface engineering.