Building Crosslinking Network via Catalytic Furan‐to‐Pyrrole Conversion

Abstract

ABSTRACT To address the limitations of conventional furan resins, which rely on furfural derivatives for synthesis and exhibit constrained performance, this work presents a catalytic polycondensation strategy that synthesizes high‐performance resins directly from furfural and amines. Catalyzed by NH 4 Cl, the process transforms furan rings into pyrrole rings via a Schiff base intermediate, proceeding through aromaticity disruption, nitrogen‐atom incorporation, and aromaticity reconstruction. This unreported mechanism constructs a multi‐substituted pyrrole cross‐linked network, which demonstrates exceptional thermal stability (450°C decomposition), flame retardancy (limiting oxygen index of 31.7%), superior mechanical strength (tensile strength of 70 MPa, flexural strength of 131 MPa), excellent fatigue resistance (a resin spring surviving 10 000 compression cycles at 95% strain), and robust adhesion to diverse substrates, particularly on stainless steel across an extremely broad temperature range (−196°C–200°C). The solvent‐free, atom‐economical method, coupled with dynamic covalent bonds enabling reprocessing, offers a sustainable pathway for biomass‐based furfural utilization and establishes a general strategy for furan‐to‐pyrrole conversion with potential in engineering plastics, structural adhesives, and coatings.