Designing Sustainable Polymers: Lactate Esters for 3D Printing and Upcycling

Abstract

The search for sustainable polymer systems is key to tackling the current climate crisis. However, the use of biobased polymers does not suffice to achieve this goal. Additionally, chemical approaches enabling the recycling or upcycling of polymer materials need to be explored. Herein, we exploit lactate esters with different substituents as readily available biobased molecules for the synthesis of printable monomers. The synthesis of these lactate ester-based monomers follows green chemistry principles by establishing a solvent-free, one-pot approach, relying on a reusable catalyst, and achieving high conversions (84−100%) under mild conditions. Further, these monomers are utilized in 3D printable ink formulations for digital light processing (DLP) for the first time in combination with a recycled crosslinker. The resulting 3D printed structures display complex geometries with high resolution. A key attribute of the presented system is that the 3D printed polymer material can be upcycled via aminolysis affording a precursor of the crosslinker, which is in turn incorporated into further ink formulations, introducing a material circularity into the system. These results demonstrate a strategic combination of a biobased monomer and chemical upcycling with sustainable 3D printing techniques.

Sustainable Vat Photopolymerization‐Based 3D‐Printing through Dynamic Covalent Network Photopolymers

“…[30] Additionally, the upcycling of printed structures through aminolysis presents another potential avenue for achieving this goal. [31] The ultimate goal is to establish a complete closed-loop system for additive manufacturing of high-performance functional photopolymers, ensuring sustainability and minimizing the environmental footprint of 3D printing processes. [32]…”

Let’s Print an Ecology in 3D (and 4D)

“…Many other scientists and researchers, such as Hod Lipson, Neil Gershenfeld, Terry Wohlers, Elaine Cohen, and Jean-Claude André, have also made significant contributions, advancing various aspects of 3D printing through their work on specific mathematical modelling techniques. Some current applications involve characterizing the shear thinning behavior of inks by quantifying the degree of shear thinning and using mathematical models to predict the window of printer operating parameters within which Overall, each group of topics concerning 3D printing in an ecological context has the potential to contribute to a more sustainable manufacturing industry by reducing material and energy use and carbon emissions [6,[55][56][57]; conserving resources [7,58,59], repairing and upcycling [56,[60][61][62] and reducing waste generation [63][64][65][66]; facilitating the selection of eco-friendly materials [67][68][69][70][71]; and enabling decentralized and customized production processes [72][73][74], thus contributing to holistic assessments of environmental impacts. In the group of publications related to modelling, there is a significant emphasis on understanding printing conditions and the properties of various printed materials.…”