Impact of zeolite content on the properties of SAPO-34/sulfonated polymer composite coatings for thermochemical energy storage

This study introduces novel SAPO-34 composite coatings using a sulfonated pentablock terpolymer (Nexar™) matrix, specifically investigating their potential for enhanced water vapor diffusion and improved performance in thermochemical energy storage (TCES) systems. Zeolite SAPO-34 composite coatings (80-95 wt.% filler) were prepared using a sulfonated pentablock terpolymer (Nexar™) matrix and characterized for their mechanical, thermal, and adsorption properties. Coatings (500-700 μm thick) were deposited on aluminium via drop casting. FTIR analysis suggest the presence of an interaction between the polymer and the zeolite mainly through carbon moieties. Thermogravimetric analysis revealed four distinct decomposition phases, with the initial phase (up to 250 °C) attributed to water removal from the zeolite, showing greater weight loss for higher zeolite content. Mechanical tests demonstrated a clear inverse relationship between zeolite content and mechanical integrity: higher zeolite loading led to increased scratch groove width, larger impact damage, and reduced adhesion strength. Pull-off testing revealed decreasing adhesion strength with increasing zeolite content, with the 80 wt.% zeolite coating exhibiting 1.32 MPa compared to 0.88 MPa for the 95 wt.% sample. Water vapor adsorption (11 mbar) showed negligible hysteresis and increased with zeolite content, reaching 28.2 wt. % for the coating containing 95 wt.% zeolite. Results highlight the impact of zeolite content, demonstrating a trade-off between adsorption and mechanical strength and confirming the coatings' potential for adsorption-based thermochemical energy storage.