Synthesis of polyenaminones by acid-catalysed amino–enaminone ‘click’ polymerisation

A mild amino–enaminone ‘click’ polymerisation method for the preparation of polyenaminones by transamination of α,α′-bis-enaminocyclopentanones with diamines was developed. A series of 12 representative polymers were synthesised by acid-catalysed transamination of two bis-enaminones with six primary 1,2-, 1,3-, and 1,4-diamines. The method allows for combinatorial preparation of structurally diverse polyenaminones from easily available diamines and bis-enaminones. The reaction mechanism was studied by NMR and MS. It involves formation of open-chain and cyclic oligomers, which then undergo a step-wise polymerisation to furnish the title polymers with high average molecular weight (Mw > 5.0 × 104 Da) and with spherical and porous microstructure. The obtained polymers were insoluble in most organic solvents, stable in diluted acids and bases, while degradable in concentrated hydrochloric acid at room temperature. They were thermally stable up to 200 °C and exhibited film-forming and UV–vis-shielding properties. © 2018 Elsevier Ltd