Thiolactone-maleimide: a functional monomer to synthesize fluorescent aliphatic poly(amide-imide) with excellent solubility via in situ PEGylation

Fluorescent poly(amide-imide)s are promising materials for use in photonics due to their controllable optical properties and excellent flexibility. Although unconventional fluorescent polymers have been flourishing recently, the fluorescence of aliphatic poly(amide-imide)s has never been realized until now. Their poor solubility and intolerance to reactive groups during synthesis prohibit access for the modification of poly(amide-imide)s. Here, we synthesize a functional thiolactone-maleimide monomer via copper(I)-catalyzed azide alkyne cycloaddition and employ a strategy combining aminolysis of thiolactones and amine-maleimide Michael addition for the synthesis of fluorescent aliphatic poly(amide-imide)s with 2-aminosuccinimide fluorophores. Moreover, in situ generated thiols enable the poly(amide-imide)s to undergo facile PEGylation via a thiol–methacrylate Michael addition reaction to accomplish excellent solubility in organic solvents and in water.