Rauhut–Currier Polyaddition: Self-Polymerization of Divalent Aryl Vinyl Ketones for Unsaturated Polyketones

The self-polyaddition of divalent vinyl ketones (VKs) by the Rauhut-Currier (RC) reaction is investigated to synthesize polymers composed of a carbon backbone. 2,7-Diacryloyl-9,9-dimethylfluorene is treated with 1,4-diazabicyclo[2.2.2]octane (DABCO) (20 mol%) and phenol (20 mol%), resulting in an improved degree of polymerization (Mn = 13800, Ð = 4.21). The polymerization is under kinetic control, probably due to the excellent electrophilicity of the VKs. However, the cyclization reaction becomes competitive during the latter stage of polymerization (conv. > 96.1%), whereas branch formation is implied by the dimerization of VK skeletons in the generated polymers. Thus, the polymerization should be controlled by the appropriate reaction time. Despite such potential side reactions, RC polymerization is notably attractive, as the resulting polyketones exhibit high thermal resistance with a 5% weight-loss temperature (Td5) of 389 °C and a remaining residue of 50 wt% even at 1000 °C. Furthermore, the VK skeletons of the polymer are quantitatively modifiable using thiol–ene click chemistry. Hence, RC polymerization affords polyketones with stable carbon backbones and reactive side-groups.