Ortyl et al. develop and implement new BODIPY-based derivatives as panchromatic, single-component polymerization photoinitiators.
Light is undeniably a fundamental tool for diverse chemical transformations in organic and polymer chemistry. Photopolymerization processes in particular, have gained widespread interest as they provide powerful, green methodologies for a variety of processes dealing with (bio)materials production, especially those involving 3D printing processes. In this aspect, due to their initiation efficiency, single-component photoinitiators are of particular interest. However, most known cationic photoinitiators have poor matching of their absorption characteristics with the emission characteristics of industrial UV light sources, the so-called medium pressure lamps and UV-LED and Vis-LED diodes.
To address this, Ortyl and collaborators developed and tested in 3D printing applications new BODIPY derivatives and more specifically iodonium salts based on a 4,4-difluoro-1,3,5,7,8-pentamethyl-4-bora-3a,4a-diaza-s-indecene (B-1) chromophore. The new tosylate, hexafluorophosphate, hexafluoroantimonate, and triflate iodonium B-1 salts were found initiate cationic photopolymerization with the hexafluoroantimonate derivative showing the highest reactivity. All derivatives were found to efficiently initiate the polymerization of a variety of monomers (such as epoxides, ethers, glycidyls and oxetanes) as well as of hybrid monomers (such as divinyl/triacrylate and diepoxide/triacrylate). Importantly, diodes of wide spectrum could be used as light source in a wavelength range from 365 to 520 nm. The applicability of the novel BODIPY derivative photoinitiators was demonstrated with 3D printing of epoxy and acrylic resins with good resolution. Moreover, the B-1 chromophore could also be used as a olorimetric sensor of the degree of photopolymerization.
In summary, BODIPY-based derivatives were developed as panchromatic, single-component polymerization photoinitiators.
Tips/comments directly from the authors:
- Newly developed cationic photoinitiators based on the BODIPY chromophore effectively initiate various photopolymerization processes.
- The choice of the appropriate concentration of new photoinitiators, current intensity, type of diode, and monomers enable to obtain polymers with a high degree of polymerization (conversions up to even 95%).
- We described the application of the new BODIPy-based photoinitiators for photo-cured 3D printing. But the newly developed photoinitiators can be successfully used in other applications, such as temporary photo-cured coloured fillings for milk teeth for children.
Development of the first panchromatic BODIPY-based one-component iodonium salts for initiating the photopolymerization processes, Polym. Chem., 2021, 12, 6873-6893.
Link to the paper: https://pubs.rsc.org/en/content/articlehtml/2021/py/d1py01263k
You can follow Professor Ortyl on Twitter: @JoannaOrtyl
Dr. Kelly Velonia is an Advisory Board Member and a Web Writer for Polymer Chemistry. She joined the Department of Materials Science and Technology in 2007. Research in her group focuses on the synthesis and applications of bioconjugates and biopolymers.