Visible light polymerization of epoxy monomers using an iodonium salt with camphorquinone/ethyl‐4‐dimethyl aminobenzoate. Issue 9 (16th January 2013) - Schroeder, Walter F
Abstract : Very rapid cationic polymerization results from visible light irradiation (470 nm) of epoxy monomers containing a diaryliodonium salt in combination with camphorquinone and an aromatic amine. Abstract: A visible light initiator system for the photoinduced cationic polymerization of epoxy monomers is reported. The system consists of camphorquinone (CQ) in combination with ethyl‐4‐dimethyl aminobenzoate (EDMAB) and a diaryliodonium salt (Ph2 ISbF6 .) The three‐component system efficiently photoinitiates the polymerization of monomers containing an epoxycyclohexane group, 3, 4‐epoxycyclohexylmethyl 3', 4'‐epoxycyclohexane carboxylate (UVR) and 1, 3‐bis(3, 4‐epoxycyclohexyl‐2‐ethyl), 1, 1, 3, 3‐tetramethyldisiloxane (SIB), under irradiation with blue light (λ = 467 nm). Very rapid photopolymerization resulted from irradiation of SIB containing Ph2 ISbF6 in combination with CQ and better results were obtained in the presence of EDMAB. On the other hand, no polymerization was detected after irradiation of UVR photoactivated with Ph2 ISbF6 and CQ. However, this monomer polymerized readily and to high conversion when EDMAB was present. Moreover, almost complete conversion of UVR occurs in the absence of external heating. The polymer resulting from UVR displayed higher values of compressive and flexural properties than the polymer prepared from SIB. This is explained in terms of a higher density of crosslinking points in UVR which is accompanied by a lower content of non‐reacted monomer; this has a plasticizing effect on the hardened material. © 2013 Society of Chemical Industry