Chemistry in light-induced 3D printing

In the last few years, 3D printing has evolved from its original niche applications, such as rapid prototyping and hobbyists, towards many applications in industry, research and everyday life. This involved an evolution in terms of equipment, software and, most of all, in materials. Among the different available 3D printing technologies, the light activated ones need particular attention from a chemical point of view, since those are based on photocurable formulations and in situ rapid solidification via photopolymerization. In this article, the chemical aspects beyond the preparation of a formulation for light-induced 3D printing are analyzed and explained, aiming at giving more tools for the development of new photocurable materials that can be used for the fabrication of innovative 3D printable devices

SELF-HEALING HYDROGELS 3D-PRINTED VIA VAT PHOTOPOLYMERIZATION

virtual European Symposium of Photopolymer Science 202

Development of New Hybrid Acrylic/Epoxy DLP-3D Printable Materials

Light induced three dimensional (3D) printing techniques generally use printable formulations that are based on acrylic monomers because of their fast reactivity, which is balanced with their good final properties. However, the possibility to enlarge the palette of 3D printable materials is a challenging target. In this work, hybrid printable formulations that are based on acrylic and epoxy resins are presented and their printability on DLP (Digital Light Processing) machines is demonstrated. Hexanediol diacrylate (HDDA) and an epoxy resin—3,4-Epoxycylohexylmethyl-3',4' epoxycyxlohexane carboxylate (CE)—in different ratios are used and the influence of a bridging agent, Glycidyl methacrylate (GMA), is also investigated. The reactivity of the different active species during irradiation is evaluated and the mechanical properties, including the impact toughness, the thermo-mechanical properties, and the volumetric shrinkage, are studied on printed samples

Recent Trends in Applying Ortho-Nitrobenzyl Esters for the Design of Photo-Responsive Polymer Networks

Polymers with light-responsive groups have gained increased attention in the design of functional materials, as they allow changes in polymers properties, on demand, and simply by light exposure. For the synthesis of polymers and polymer networks with photolabile properties, the introduction o-nitrobenzyl alcohol (o-NB) derivatives as light-responsive chromophores has become a convenient and powerful route. Although o-NB groups were successfully exploited in numerous applications, this review pays particular attention to the studies in which they were included as photo-responsive moieties in thin polymer films and functional polymer coatings. The review is divided into four different sections according to the chemical structure of the polymer networks: (i) acrylate and methacrylate; (ii) thiol-click; (iii) epoxy; and (iv) polydimethylsiloxane. We conclude with an outlook of the present challenges and future perspectives of the versatile and unique features of o-NB chemistry

In Situ Thermal Generation of Silver Nanoparticles in 3D Printed Polymeric Structures

Polymer nanocomposites have always attracted the interest of researchers and industry because of their potential combination of properties from both the nanofillers and the hosting matrix. Gathering nanomaterials and 3D printing could offer clear advantages and numerous new opportunities in several application fields. Embedding nanofillers in a polymeric matrix could improve the final material properties but usually the printing process gets more difficult. Considering this drawback, in this paper we propose a method to obtain polymer nanocomposites by in situ generation of nanoparticles after the printing process. 3D structures were fabricated through a Digital Light Processing (DLP) system by disolving metal salts in the starting liquid formulation. The 3D fabrication is followed by a thermal treatment in order to induce in situ generation of metal nanoparticles (NPs) in the polymer matrix. Comprehensive studies were systematically performed on the thermo-mechanical characteristics, morphology and electrical properties of the 3D printed nanocomposites

Digital light processing 3D printing of dynamic magneto-responsive thiol-acrylate composites

Additive manufacturing is one of the most promising processing techniques for fabricating customized 3D objects. For the 3D printing of functional and stimuli-triggered devices, interest is steadily growing in processing materials with magnetic properties. Synthesis routes for magneto-responsive soft materials typically involve the dispersion of (nano)particles into a non-magnetic polymer matrix. Above their glass transition temperature, the shape of such composites can be conveniently adjusted by applying an external magnetic field. With their rapid response time, facile controllability, and reversible actuation, magnetically responsive soft materials can be used in the biomedical field (e.g. drug delivery, minimally invasive surgery), soft robotics or in electronic applications. Herein, we combine the magnetic response with thermo-activated healability by introducing magnetic Fe3O4 nanoparticles into a dynamic photopolymer network, which undergoes thermo-activated bond exchange reactions. The resin is based on a radically curable thiol-acrylate system, whose composition is optimized towards processability via digital light processing 3D printing. A mono-functional methacrylate phosphate is applied as a stabilizer to increase the resins' shelf life by preventing thiol-Michael reactions. Once photocured, the organic phosphate further acts as a transesterification catalyst and activates bond exchange reactions at elevated temperature, which render the magneto-active composites mendable and malleable. The healing performance is demonstrated by recovering magnetic and mechanical properties after the thermally triggered mending of 3D-printed structures. We further demonstrate the magnetically driven movement of 3D-printed samples, which gives rise to the potential use of these materials in healable soft devices activated by external magnetic fields

Study on the Printability through Digital Light Processing Technique of Ionic Liquids for CO2 Capture

Here we present new 3D printable materials based on the introduction of different commercially available ionic liquids (ILs) in the starting formulations. We evaluate the influence of these additives on the printability of such formulations through light-induced 3D printing (digital light processing-DLP), investigating as well the effect of ionic liquids with polymerizable groups. The physical chemical properties of such materials are compared, focusing on the permeability towards CO2 of the different ILs present in the formulations. At last, we show the possibility of 3D printing high complexity structures, which could be the base of new high complexity filters for a more efficient CO2 capture

Dual-curable vitrimers for 3d-printing

3D-printed objects can greatly benefit from the introduction of molecular structure undergoing dynamic bond exchange [1] or the use dual-curing processing [2], leading to a significant enhancement of mechanical properties and extended capabilities such as adhesion, reshaping, healing and recycling. We have developed a family of dual-curing 3D-printable materials based on acrylate homopolymerization for the printing stage and epoxy-acid reaction for the second thermal curing stage, with the purpose 1) having a stable intermediate material with desired reshaping and adhesion capabilities and 2) obtaining a network structure capable of undergoing dynamic work rearrangement promoted by transesterification between ester and available hydroxyl groups. A latent amine catalyst has been added in order to accelerate both the thermal curing stage and transesterificationPeer ReviewedPostprint (author's final draft