Synthesis of Degradable Mainchain Semifluorinated Polyester by CuAAC with Reaction-Enhanced Reactivity of Intermediate (RERI) Mechanism.

Abstract

Quantitative insertion of functionality into polymer chains via step-growth polymerization is challenging due to the random bimolecular reaction and relatively low extent of reaction. Herein, a copper-catalyzed azide-alkyne cycloaddition (CuAAC) step-growth polymerization with reaction-enhanced reactivity of intermediates (RERI) mechanism is applied for the precise insertion of degradable functions into the mainchain semifluorinated polymer and endowed it with controlled degradability. In this CuAAC polymerization, bis-alkynyl-terminated (A₂) monomer can be quantitatively consumed when the slightly excess of 2,2-bis(azidomethyl)propane-1,3-diyl bis(2-methylpropanoate) (BiAz, B₂) monomer with RERI effect is employed. The CuAAC copolymerization of o-nitrobenzyl ester-derived A₂ (A₂-ONB), fluorinated A₂ (A₂-F), and B₂ monomers produced the mainchain semifluorinated copolymers with tunable chemical composition and high molecular weight, along with the random and quantitative insertion of [A₂-ONB] units. These mainchain semifluorinated copolymers are capable of controlled degradation profile under ultraviolet radiation and can undergo complete degradation under basic condition. This work provided a simple approach for preparing mainchain semifluorinated polymers with controlled degradability.