Additive Manufacturing of Poly(phenylene Sulfide) Aerogels via Simultaneous Material Extrusion And Thermally-Induced Phase Separation.

Additive manufacturing (AM) of aerogels increases the achievable geometric complexity, and affords fabrication of hierarchically-porous structures. In this work, a custom heated material extrusion (MEX) device prints aerogels of poly(phenylene sulfide) (PPS), an engineering thermoplastic, via in-situ thermally induced phase separation (TIPS). First, pre-prepared solid gel inks are dissolved at high temperatures in the heated extruder barrel to form a homogeneous polymer solution. Solutions are then extruded onto a room-temperature substrate, where printed roads maintain their bead shape and rapidly solidify via TIPS, thus enabling layer-wise MEX AM. Printed gels are converted to aerogels via post-processing solvent exchange and freeze-drying. This work explores the effect of ink composition on printed aerogel morphology and thermo-mechanical properties. Scanning electron microscopy micrographs reveal complex hierarchical microstructures that are compositionally dependent. Printed aerogels demonstrate tailorable porosities (50.0 - 74.8%) and densities (0.345 - 0.684 g cm -3 ), which align well with cast aerogel analogs. Differential scanning calorimetry thermograms indicate printed aerogels are highly crystalline (∼ 43%), suggesting that printing does not inhibit the solidification process occurring during TIPS (polymer crystallization). Uniaxial compression testing reveals that compositionally-dependent microstructure governs aerogel mechanical behavior, with compressive moduli ranging from 33.0 to 106.5 MPa. This article is protected by copyright. All rights reserved.