Fast Visible-Light 3D Printing of Conductive PEDOT:PSS Hydrogels.

Functional inks for light based 3D printing are actively being searched for being able to exploit all the potentialities of additive manufacturing. Here we show a fast visible-light photopolymerization process of conductive PEDOT:PSS hydrogels. For this purpose, a new Type II photoinitiator system (PIS) based on riboflavin (Rf), triethanolamine (TEA) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) was investigated for the visible light photopolymerization of acrylic monomers. PEDOT:PSS has a dual role by accelerating the photoinitiation process and providing conductivity to the obtained hydrogels. Using this PIS, full monomer conversion is achieved in less than 2 min using visible light. Firstly, the PIS mechanism was studied, proposing that electron transfer between the triplet excited state of the dye ( 3 Rf*) and the amine (TEA) is catalyzed by PEDOT:PSS. Secondly, a series of poly(2-hydroxyethyl acrylate)/PEDOT:PSS hydrogels with different compositions were obtained by photopolymerization. The presence of PEDOT:PSS negatively influences the swelling properties of hydrogels, but significantly increases its mechanical modulus and electrical properties. The new PIS has also been tested for 3D printing in a commercially available Digital Light Processing (DLP) 3D printer (405 nm wavelength), obtaining high resolution and 500 μm hole size conductive scaffolds. This article is protected by copyright. All rights reserved.