Structural, Thermal, and Surface Properties of PVDF/Silica Aerogel Nanocomposite Membranes for Membrane Distillation Application

This study addresses membrane distillation's key challenges - wetting and thermal inefficiency - by developing PVDF/silica aerogel nanocomposite membranes with optimized sublayer properties. We fabricated membranes with systematic variations in PVDF concentration (12-21%) and silica aerogel loading (1-3%), characterizing their structural and surface properties. FTIR analysis confirmed successful nanoparticle incorporation without altering PVDF chemistry. Porosity exhibited concentration-dependent behavior: increasing with silica at 12% PVDF, stable at 18%, and decreasing at 21% due to viscosity effects on phase separation. All nanocomposites showed reduced thermal conductivity, enhancing insulation. While skin layer hydrophobicity remained constant, silica migration significantly increased sublayer contacts angles (peak 130.6° for 18% PVDF/3% silica, 20% improvement over control). The 18% PVDF formulation demonstrated optimal balance, maintaining structural integrity while achieving high porosity (78.3%) and low thermal conductivity (0.048 W/mK). These results highlight two critical findings: (1) PVDF concentration dictates nanoparticle effects on membrane morphology, and (2) strategic silica incorporation simultaneously enhances sublayer hydrophobicity and thermal resistance without compromising mechanical stability. The study provides a design framework for MD membranes, demonstrating how sublayer engineering can mitigate wetting while improving thermal efficiency - crucial advancements for practical MD implementation.