Experimental Design Optimization of Acrylate—Tannin Photocurable Resins for 3D Printing of Bio-Based Porous Carbon Architectures

Abstract

In this work, porous carbons were prepared by 3D printing formulations based on acrylate–tannin resins. As the properties of these carbons are highly dependent on the composition of the precursor, it is essential to understand this effect to optimise them for a given application. Thus, experimental design was applied, for the first time, to carbon 3D printing. Using a rationalised number of experiments suggested by a Scheffé mixture design, the experimental responses (the carbon yield, compressive strength, and Young’s modulus) were modelled and predicted as a function of the relative proportions of the three main resin ingredients (HDDA, PETA, and CN154CG). The results revealed that formulations containing a low proportion of HDDA and moderate amounts of PETA and CN154CG gave the best properties. Thereby, the optimised carbon structures had a compressive strength of over 5.2 MPa and a Young’s modulus of about 215 MPa. The reliability of the model was successfully validated through optimisation tests, proving the value of experimental design in developing customisable tannin-based porous carbons manufactured by stereolithography.

3D-Printed Carbons with Improved Properties and Oxidation Resistance

“…Consequently, this limits the final carbon yield too . It is thus of interest to design a biobased aromatic monomer with high solubility inor compatibility withacrylate to improve the carbon yield and the mechanical properties of the resulting 3D-printed carbon compared to 3D carbon derived from acrylate–tannin photosensitive resins. , …”

“…11,12 Therefore, many efforts have been made to develop biobased alternatives to produce 3D-printed porous carbon with attractive yield, reduced shrinkage, and good mechanical properties. 13,14 In this context, mimosa tannin has been identified as a suitable biobased precursor to achieve such a specification, in particular with properties that can be adapted to energy and environmental applications such as electromagnetic absorption or catalysis, among others. However, as tannin is not soluble in acrylate resins, the viscosity of the obtained dispersion limits its incorporation into the photoreactive resin to less than 30 wt %.…”

“…Finally, the architectures were converted into porous carbon materials under an inert atmosphere (nitrogen at a flow rate of 75 mL min −1 ) in a tubular furnace with the following thermal program: heating ramp at 1.5 °C min −1 to 300 °C, 60 min step at 300 °C, heating at 1 °C min −1 to 400 °C, 60 min step at 400 °C, and finally heating at 2 °C min −1 to a final temperature of 900 °C, which was maintained for 1 h, as described elsewhere. 14 The resulting carbons were named cA−T, cA−Vm−T, cA−Tm, and cA−Vm−Tm, respectively.…”

“…15 It is thus of interest to design a biobased aromatic monomer with high solubility in� or compatibility with�acrylate to improve the carbon yield and the mechanical properties of the resulting 3D-printed carbon compared to 3D carbon derived from acrylate−tannin photosensitive resins. 13,14 In recent years, significant work has been done to develop biobased vinyl ester resins (VERs) from natural phenolic compounds such as vanillin. 16−19 Vanillin, as a natural biomass-derived molecule, has proven to be a perfect candidate for use in VERs and stereolithographic printing.…”

“…As expected, due to a denser structure, the mechanical properties of the 3D-printed carbons studied in this work were superior to those of previously studied carbons based on acrylate−tannin resin. 13,14 In the broader context of carbon monoliths, the 3D-printed carbons derived from Vm and Tm precursors exhibit similar or most of the time better mechanical properties than other stereolithographically printed petroleum-derived carbons, direct ink writing (DIW)-printed carbons, or carbon foams and gels with densities in the range 0.4 to 0.7 g cm −3 . 6,13,14,49−52 These results may be interpreted in terms of a thick matrix containing fewer and fewer pores, which leads to much stiffer carbon materials than typical carbon foams, which typically have much thinner struts.…”