Different Strategies for Developing an Electrically Conductive and Flexible Composite by DLP 3D Printing

Additive manufacturing (AM), or 3D printing, is one of the main elements in the development of Industry 4.0, which can increase plant productivity and improve product quality. Indeed, thanks to the layer-by-layer manufacturing approach, AM opens up the possibility of mass customization of products by achieving complex designs, with minimal material waste. However, despite the several advantages of AM, the widespread usage of this technology is still limited by several factors, such as surface finish, standardization, and lack of materials. In this context, the primary contribution of this work involves the design and synthesis of a flexible and electroconductive composite, being the flexibility and conductivity essential properties in various industries, spanning from electronics, to sensors, and wearable technology. In particular, we are focusing our research on different strategies for including a conductive polymer, i.e. polyaniline (PANI), into a poly(ethylene glycol) diacrylate (PEGDA) matrix by using a Digital Light Processing (DLP) [et1] 3D printer. Such printing technique typically makes use of a light to selectively cure a thin layer of a photosensitive ink. However, the 3D printing technology for CPs is still in its early stages and faces many challenges, mainly related to poor solubility and printability of CP systems. In this context, we report two different protocols for producing PEGDA-PANI items by means of a DLP 3D printer. In the first, an in-situ approach is exploited to synthetize PANI inside a printed PEGDA substrate, by combining 3D printing with a subsequent chemical oxidation process. Conversely, the second approach exploits the printer UV light to start the photopolymerization of aniline monomers directly during a PEGDA printing process. The PEGDA-PANI systems produced by both the methods show suitable morphological and structural features, as well as electrical and electrochemical performances, making them potentially useful for various soft electronics applications.<br/>The two distinct production methods developed highlight the versatility and adaptability of 3D printing in producing electroconductive materials. Moreover, the possibility to produce flexible and customizable electronics provides broader implications for various industries, as an expanded list of available materials for AM opens doors to novel product designs and functionalities.