(604i) Rheology-Manipulated Feedstocks for in-Line Sublayers in a New 3D Printing Mechanism

Rheology control in general polymer processing plays a key role, such as extrusion or injection molding. However, current research studying the role of rheology in additive manufacturing has been limited to the shear-thinning behavior not to clog the printhead. This research will study the flow behavior between different polymer solutions to facilitate phase compatibility during the co-flow within the printing process. This new printing, namely, multiphase direct ink writing (MDIW), will leverage the complex and unique design of the printhead to separate and rearrange the polymer solutions continuously without disrupting the layer formation. As a result, the polymer feedstocks can be tunable with desirable compositions, e.g., polymer blends, polymer-filler compounds, polymer-nanoparticle suspensions, and nanoparticle colloids. Materials written with the MDIW on a specific substrate will have sublayers, with the subdomain size ranging from hundreds to tens of microns containing nanometer elements and nanoscale structural control. In manufacturing, the resolution enhancement has shown high effectiveness in improving mechanical, thermal, and other functional properties. For example, the inclusion of nanoparticles with better dispersions will increase the mechanical modulus and toughness. A few different polymers and nanoparticles also demonstrated the feasibility of controlling composite responsiveness as a function of thermal or magnetic fields. Therefore, our unique method shows the power of managing the feedstock flow behavior and its broad applications in structural supports, thermal dissipation, microelectronics, and metasurfaces.