Near-collector electroprinting of cellulose acetate structures with large specific surface per volume

Abstract

This study focuses on the fabrication and analysis of 3D-printed high-detail resolution cellulose acetate (CA) structures, particularly examining their specific surface area per volume $\left(S_v\right)$. While electrospinning is a widely used technique for creating nanofiber membranes with high $S_v$, which is advantageous for applications like chromatography, the performance could be further improved by precisely controlling fiber placement. To further develop membranes, this research explores the use of electroprinting with small distances between nozzle and collector, here named near-collector electroprinting, to create 3D structures. By optimizing printing parameters, in particular the reduction of the nozzle-to-collector distance, 3D structures with precise fiber placement within a few micrometers were fabricated. The specific surface area per volume was calculated for both 3D-printed and electrospun filters. Results showed that 3D-printed structures with a 5 μm pitch achieved a $S_v$ similar to electrospun filters.

Incorporating polyethyleneimine (PEI) in the CA ink enabled the 3D-printed structures to gain ion binding capacity which was further investigated. This ion-exchange ability which integrated into the printing step, eliminating the need for a separate post-modification process in bio-separation applications. By switching the substrate voltage from positive to negative, relative to the grounded nozzle, the printed fiber diameter decreased substantially for the CA ink with PEI. The $S_v$ for near-collector electroprinted fibers of this material could therefore potentially be higher than that of electrospun membranes, provided that an order of magnitude higher printing speed, than presently possible can be used. These findings suggest that near-collector electroprinted CA structures offer potential improvements in membrane design and performance, making them a promising alternative to traditional electrospun membranes for bio-separation applications.