Copolyesters with branched structures for simultaneous fluorescence and resilience

Abstract

The development of non-conjugated polymers that simultaneously exhibit fluorescence and mechanical resilience remains a significant challenge. Herein, we report a series of branched copolyesters that display blue-green clusteroluminescence (CL) alongside excellent elasticity. A synthetic strategy involving the “design and incorporation of branched structures” was employed to fabricate these copolyesters with tunable repeat-unit compositions. Specifically, 1,3-butanediol, featuring a methyl side chain, was first converted into a branched monomer via alcoholysis with succinic anhydride. This monomer was then copolymerized with 1,4-butanediol and terephthalic acid, yielding copolyesters with tailored branched architecture. As the content of branched structures increases, the crystallinity of the copolyesters is progressively disrupted, leading to a transition from plastic to elastic behavior. The resulting materials demonstrate an elastic recovery rate exceeding 60% under multiple strains (20–300%) and exhibit outstanding fatigue resistance. Moreover, the introduction of branched units balances the flexibility and rigidity of the molecular chains, thereby enhancing the fluorescence performance. The fluorescence quantum yield of the branched copolyester is up to ∼9 times higher than that of its linear counterpart, endowing the material with potential for applications in ion detection and fatigue monitoring. Notably, these copolyesters are amenable to multiple melt-reprocessing cycles, exhibit excellent biocompatibility, and demonstrate superior biodegradability. This work not only presents a novel strategy for designing polymers that integrate fluorescence with resilience, but also offers new insights into the application prospects of luminescent polyesters, particularly in the field of fluorescence fatigue monitoring.