Piezoresistive composites via additive manufacturing and composite filaments associated therewith

A printed part comprising:

• a continuous printed polymer matrix comprising a first thermoplastic polymer and a second thermoplastic polymer that are immiscible with one another;
• wherein the first thermoplastic polymer is dissolvable or degradable under specified conditions, and the second thermoplastic polymer is insoluble or non-degradable under the specified conditions;
• and
• wherein the first thermoplastic polymer and the second thermoplastic polymer are distributed co-continuously in the continuous printed polymer matrix and define an interpenetrating network;
• and
• a plurality of electrically conductive particles distributed in the continuous printed polymer matrix, the plurality of electrically conductive particles comprising microparticles, nanoparticles, or any combination thereof.

A method comprising:

• combining a plurality of electrically conductive particles and a first thermoplastic polymer that is water-soluble with an aqueous dispersion of a second thermoplastic polymer that is water-insoluble to provide a combined aqueous mixture;
• removing water from the combined aqueous mixture to provide a composite residue comprising at least a portion of the electrically conductive particles distributed in a continuous polymer phase comprising the first thermoplastic polymer and the second thermoplastic polymer, the first thermoplastic polymer and the second thermoplastic polymer being immiscible with one another in the continuous polymer phase,
• wherein the first thermoplastic polymer and the second thermoplastic polymer are distributed co-continuously in the composite residue and define an interpenetrating network;
• and
• extruding the composite residue into a composite filament comprising the electrically conductive particles distributed in the continuous polymer phase;
• wherein the composite filament has a diameter of about 1.0 mm to about 10.0 mm and a spoolable length of at least about 1 foot.