[Back]

G. Peer, T. Koch, C. Gorsche, R. Liska:
"New monomers for photopolymerization based on radical cyclopolymerization";
Talk: 5th European Symposium of Photopolymer Science, Mulhouse, France; 2018-09-03 - 2018-09-06; in: "5th European Symposium of Photopolymer Science", 5th European Symposium of Photopolymer Science, (2018), 13.

Butler et al. discovered the mechanism of radical cyclopolymerization in the 1950s, where difunctional enes form rigid linear polymer chains instead of a polymer network via an alternating intra-intermolecular cyclization and propagation mechanism.1 Butler initially investigated quaternary diallyl ammonium salts, whereas a wide range of different enes are capable of cyclopolymerization. Kodaira et al. published an extensive review of possible radically cyclopolymerizable structures such as di(meth)acrylamides, diallyl ethers or N-substituted diallyl amines.2 The polymerization behaviour of aforementioned monomer classes, when thermally initiated is well documented, in contrast to photoinitiated radical cyclopolymerization, where examples are scarce. Hall et al. showed different monomeric and dimeric diallylamines polymerized via photopolymerization in order to achieve new coating systems.3 Other examples are self-photoinitiating cyclopolymerizable monomers, which were investigated by Karasu et al.4

In this paper, we present the synthesis of different cyclopolymerizable monomers (CPMs, i.e. ester activated, N-substituted diallyl amines5, Figure 1.) and the application of these monomers in photocurable formulations. We investigated the solvent-free homopolymerization performance of the CPMs and their copolymerization behaviour with methacrylates. Different bulky side groups were attached to not only enhance the cyclization reaction, but also yield a rigid backbone with hindered rotational freedom. The most promising candidate, the adamantyl derivative was applied in a copolymerization with a crosslinking dimethacrylate, in order to achieve materials with a high heat deflection temperature. A state-of-the-art monofunctional methacrylate (i.e. isobornylmethacrylate) with a high heat deflection temperature was used as reference material and the reactivity and (thermo)mechanical properties of the resins were determined. All investigated CPMs show fast photopolymerization behaviour and the resulting polymers exhibit exceptionally high heat deflection temperature.

the mechanism of radical cyclopolymerization, the synthesis of different cyclopolymerizable monomers , the application of these monomers in photocurable formulations