3D reactive inkjet printing of bisphenol A-polycarbonate

Abstract

Additive Manufacturing (AM) techniques have gained extensive attention recently as they are able to directly produce 3D parts utilising a layer-by-layer manner. Inkjet printing is one such technique which can produce micron-scale features but is generally constrained to liquid viscosities of less than 30 mPa·s, therefore available materials are limited. A 3D reactive inkjet printing (3DRIJP) approach to deposit low viscosity monomers and polymerise in-situ to form polymer parts is emerging. In this work, a 3DRIJP approach has been developed to fabricate bisphenol A-polycarbonate (BPA-PC) for the first time by using a low viscosity reactive ink containing monomers, catalyst and solvent. A set of processing parameters were explored and optimised including temperature of droplet formation, substrate temperature and droplet spacing to print films. With a thermal post-curing process, BPA-PC was formed successfully with a molecular weight comparable to those which were manufactured by the conventional melt transesterification process. The thermal properties were evaluated suggesting good thermal resistance characteristics. Finally, a 3D ziggurat structure was printed to demonstrate the capability to fabricate BPA-PC by an AM method, thus broadened the library of AM materials to include engineering grade polymers via 3DRJIP. This approach was innovative in both the BPA-PC material formulation and the 3DRIJP process development from traditional inkjet printing methods, where a single printable formulation of monomers for thermoplastic optical-clear BPA-PC was able to be printed using one printhead to form 3D structures.