New 3D Printable Polymeric Materials for Fused Filament Fabrication (FFF)

3D printing, also known as additive manufacturing, is an advancing technology for fabricating three dimensional objects of simple to complex architectures using computer aided design (CAD) models. Fused Filament Fabrication (FFF) is a relatively cost effective, straightforward 3D printing technique which relies upon utilization of relatively cheap, commercially available thermoplastics like polylactic acid (PLA) and acrylonitrile-butadiene-styrene (ABS) in a coil form to fabricate desired objects in layer-by-layer fashion on a print bed. In spite of the growing popularity of FFF, the technique suffers from poor mechanical strength of 3D printed parts due to weak inter-layer adhesion at interfilamentous junctions. To address these issues related to the materials used for FFF 3D printing, for the first time, we introduce a polymer blending strategy that utilizes Diels-Alder (DA) dynamic covalent chemistry which plays the model role for remending PLA. A partially cross-linked terpolymer having furan-maleimide DA linkages both in the main chain and at cross-linking junctions is used as the mending agent (MA). Results indicate dramatic improvements in both ultimate strength and toughness along the z-print axis for remendable PLA than pristine PLA. As a follow-up, we increase the cross-linking density of the MA polymer to yield remendable PLA with isotropic mechanical properties. Finally we are introducing utilization of hydrogels, prepared from a cheap, abundant, biopolymer and 3D printed via direct-write 3D printing technique based on FFF principles, for the removal of toxic heavy metal ions from contaminated water. With promising results in mechanical strength, metal adsorption efficiency, and recyclability, the strategy lays a foundation for future design and development of cheap, safe, and durable 3D printable materials for water purification. Chapter 1 provides a general introduction on 3D printing techniques, issues related to FFF, our approaches to address the issues, and utilizing hydrogel materials in direct-write 3D printing. Chapter 2 describes a design paradigm utilizing reversible Diels-Alder reactions to enhance the mechanical properties of 3D printed materials. Chapter 3 describes 3D printed remendable polylactic acid blends with uniform mechanical strength enabled by a dynamic Diels-Alder reaction. Chapter 4 describes 3D printable hydrogels for toxic heavy metal adsorption from water.