Additive manufacturing of poly(phenylene sulfide) aerogels by simultaneous material extrusion and thermally induced phase separation

Polyphenylene sulfide (PPS) aerogels formed from a nontoxic and environmentally friendly solvent are manufactured using material extrusion (MEX) and thermally induced in situ phase separation (TIPS). The printed aerogels demonstrate geometric flexibility and hierarchical porosity while retaining the physical properties inherent to cast analogues. This novel additive manufacturing process chain presents a simple method to develop printed polymer aerogels from TIPS systems requiring high processing temperatures.

Abstract

Additive manufacturing (AM) of aerogels increases the achievable geometric complexity and enables the fabrication of hierarchical porous structures. In this work, a customized heated material extrusion (MEX) device prints poly(phenylene sulfide) (PPS) aerogels, an engineering thermoplastic, via thermally induced in situ phase separation (TIPS). First, pre-prepared solid gel inks are dissolved at high temperature in the heated extrusion barrel to form a homogeneous polymer solution. The solutions are then extruded onto a substrate at room temperature, where the printed routes maintain their bead shape and rapidly solidify via TIPS, enabling layer-by-layer MEX AM. The printed gels are converted to aerogels via post-processing solvent exchange and freeze-drying. This work explores the effect of ink composition on the morphology and thermomechanical properties of the printed aerogels. Scanning electron microscopy micrographs reveal complex hierarchical microstructures that depend on composition. The printed aerogels exhibit customizable porosities (50.0–74.8%) and densities (0.345–0.684 g cm).⁻³), which align well with cast aerogel analogues. Differential scanning calorimetry thermograms indicate that the printed aerogels are highly crystalline (≈43%), suggesting that printing does not inhibit the solidification process occurring during TIPS (polymer crystallization). Uniaxial compression tests reveal that the composition-dependent microstructure governs the mechanical behavior of the aerogel, with compressive moduli ranging from 33.0 to 106.5 MPa.