3D Printing of Mixed Matrix Films Based on Metal–Organic Frameworks and Thermoplastic Polyamide 12 by Selective Laser Sintering for Water Applications

The fabrication of metal–organic framework (MOF)-based macro-materials is considered as a promising strategy toward the practical applications of powdered MOF crystals. In this study, selective laser sintering (SLS), an advanced three-dimensional (3D) powder printing technique, has been employed to fabricate MOF–polymer mixed matrix films (MMFs) by using thermoplastic polyamide 12 (PA12) powder as the matrix material and five types of MOFs including ZIF-67, NH2-MIL-101­(Al), MOF-801, HKUST-1, and ZIF-8 crystals as the fillers. A three-layer HKUST-1-PA12 complex with a grid pattern is fabricated to demonstrate the printability of 3D MOF–polymer structure. Single-layer MMFs with grid patterns are printed by using the five types of MOF fillers with different mass loadings to study their free-standing characteristic, thickness, specific surface area, hydrophilia, water permeate flux, and mechanical stability. The methylene blue (MB) adsorption tests are conducted using the NH2-MIL-101­(Al)-PA12 MMFs with different grid patterns to exemplify the applications of the MMFs for water purification. It is confirmed that the MOF components retain their high maximum adsorption capacity, and the printed MMFs can be conveniently regenerated for cyclic utilization. This work provides an insight into the utilization of advanced 3D printing technology to manufacture macro-MOF–polymer materials for practical applications.