3D and 4D printed polymers for solid phase extraction and pollutant removal applications

Addressing global environmental challenges calls for advanced materials capable of efficient pollutant removal and solid-phase extraction. This review examines recent developments in polymers fabricated by threedimensional (3D) and four-dimensional (4D, stimuli-responsive) printing methods. It highlights how 3D-printed structures offer customizable geometries, increased porosity, and enhanced surface area to improve adsorption performance. In addition, using smart, 4D-responsive polymers allows for changes in shape or controlled release when triggered by outside factors (like temperature or pH), which adds a new level of functional control. We assess printing technologies, like fused deposition modelling, stereolithography, digital light processing, and direct ink writing, and compare strategies for polymer functionalization, composite formulation, and performance in removing heavy metals, organic pollutants, and pharmaceutical residues from complex samples. This comprehensive overview emphasizes both the scientific advances and remaining challenges, guiding future innovation in sustainable, high-performance 3D/4D printed polymer materials.