Multiscale additive manufacturing of polymers using 3D photo-printable self-assembling ionic liquid monomers

3D photoprinting of a self-assembled ionic liquid (IL) monomer based liquid-crystalline mesophase introduces high-resolution nanoscale features (2-5 nm) into otherwise low-resolution (microscale features) polymer builds. A wide variety of geometric builds possessing internal hexagonal perforated lamellar (HPL) nanostructure containing similar to 2.4 nm diameter pores are fabricated by the digital light processing 3D printing of an aqueous mixture (61(w/w%)) of an ionic liquid monomer, 1-decyl-3-vinylimidazolium chloride, a co-monomer, polyethylene diacrylate (PEGDA, M-n 575), and a visible light photo-initiator (eosin Y and triethanolamine). Vibrational spectroscopy and thermal analysis proves acrylate moiety polymerization occurs during printing but incomplete consumption of the IL vinyl groups. Post-printing exposure to UV light (lambda 350 nm) completes vinyl polymerization serving to further improve nanostructure ordering as determined by SAXS. Solvent swelling (ethanol) induces a structural transformation to a body center cubic architecture accompanied by slight pore expansion (to 3.2 nm). The introduction of nanoscale features into low-resolution photo-printed polymers establishes a low-cost strategy for the additive manufacturing of multi-scale, structured nanoporous polymer membranes.