Aryliodonium Ylides as Novel and Efficient Additives for Radical Chemistry: Example in Camphorquinone (CQ)/Amine Based Photoinitiating Systems

• Main Authors: Julie Kirschner, Julien Paillard, Mariem Bouzrati-Zerelli, Jean-Michel Becht, Joachim E. Klee, Saloua Chelli, Sami Lakhdar, Jacques Lalevée
• Format: Article
• Language: English
• Published: MDPI AG 2019-08-01
• Series: Molecules
• Subjects: photoinitiator; iodonium salt; radical initiation; photopolymerization
• Online Access: https://www.mdpi.com/1420-3049/24/16/2913

Diaryliodonium salts are well-established compounds in free radical chemistry and are already used as photoinitiators (free radical or cationic polymerization), but the presence of counter anions is a strong drawback. Indeed, a counter anion is always required (e.g., SbF₆^−) leading to potential toxicity issues or release of HF. In the present paper, counter anion-free and fluoride-free aryliodonium salts are proposed, that is, aryliodonium ylides (AY) are studied here as new and efficient additives for radical chemistry and an example is provided for the camphorquinone (CQ)/amine based photoinitiating systems (PISs) for the polymerization of thick (1.4 mm) and thin (20−13 µm) methacrylates under air and blue light irradiation. The newly proposed PISs, for example, CQ/amine/AY, presented excellent polymerization performances and good bleaching properties were obtained after polymerization. Real-time Fourier transform infrared spectroscopy (RT-FTIR) was used to monitor the photopolymerization profiles. The chemical mechanisms involved were investigated using electron spin resonance (ESR).