3D printing structured nanocelluloses and their composites: Printability, structures, and properties

Abstract

Cellulose remains to be one of the most renewable and abundant engineering material used in current society. In the past decade, a new area of cellulosic materials in the nanoscale regime, also known as nanocellulose, has emerged. Two of the most fundamental forms of nanocellulose are cellulose nanocrystals (CNCs) and cellulose nanofibers (CNFs), which are typically generated from cellulosic biomass degradation through a combination of mechanical, thermal, or chemical treatments. Along with the advent of nanocellulose, 3D additive manufacturing also allows complex structures to be efficiently produced based on user’s customized electronic designs, while also satisfying on-demand fabrication without needing complex parts or tools. Although it is desirable to fabricate nanocellulose based products with 3D printing, it remains as a challenge to not only make nanocellulose based formulations that are 3D printable, but also fabricate the 3D structure with high structural complexity, good shape quality, and tunable properties. Therefore, the main purpose of this thesis dissertation is to not only produce nanocellulosic formulations with good 3D printability, but also fabricate shape customizable, print quality controllable, and functionality tunable nanocellulosic 3D products that are suitable for different engineering applications. Overall, digital light processing (DLP) 3D printing was used to fabricate CNCs-polyethylene glycol based composites with potential biomedical applications, direct-ink-write (DIW) 3D printing was used to make CNCs and CNFs aerogels with potential tissue engineering, oil-water separation, or electrical applications, and multi-materials-multi-methods (M4) hybrid 3D printing and CNCs based support material were used to fabricate complexly shaped structures with potential prototyping applications. Thus, this dissertation was able to verify the ability to make nanocellulosic formulations with excellent 3D printability, and the resultant nanocellulosic composites and structures demonstrated the structural complexity, shape fidelity, and tailorable functionality that are needed in different potential engineering applications.