Abstract
Composite and hybrid materials displaying layered structures have broad applications in structural composites, fire retardant barriers, tissue scaffolds, and microelectronics. Inspired by biosystems, in this study, we explore the invention of a new 3D printing principle that can produce layered structures similar to those in trees, overcoming the bottleneck in additive manufacturing to include multi-materials. We use polyvinyl alcohol (PVA) and carbon nanotubes (CNTs) as material examples for producing alternating layers. With the unique 3D printing platform, Multiphase Direct Ink Writing (MDIW), the optimized dispersion quality and rheology behaviors allow the number of layers within an individual printing line to change between 4 and 512 layers. The mechanical tests consistently increased young’s modulus and ultimate tensile strength with decreased layer thickness and dispersion quality. The best-performed composites have 128 layers in one printing line, beyond which the dispersion of CNTs deteriorated due to aggregates. Due to the thin layer thickness, the improved composite mechanics relate to the closely packed CNTs and their alignment.
Moreover, we will also demonstrate this MDIW printing with different polymers (e.g., thermoplastic urethane and polylactic acid) and nanoparticles (e.g., iron oxide, carbon fibers) for mechanical enhancement and intelligent behaviors. This research demonstrated one new 3D printing method, MDIW, that can fabricate multilayered composites containing well-managed content in each layer. Our advanced manufacturing method is compatible with other materials and has potential use in batteries, supercapacitors, solar cells, regenerative medicine, and energetic systems requiring layered structures.
