Segmented polyfluorene copolymers grafted with poly(vinylidene fluoride) chains for synchronized piezoelectric response and electroluminescence

초록

We propose segmented copolymers with spatially segregated regions exhibiting piezoelectric response and electroluminescence within a single polyfluorene-based conjugated polymer chain. To achieve the material, segments with anchoring sites for poly(vinylidene fluoride) (PVDF) and segments containing benzothiadiazole units were polymerized separately as oligomers and then combined in a single reactor to form the desired copolymer. To control segment lengths, a technique was developed to monitor oligomer solution viscosity during parallel polycondensation, convert the viscosity to molecular weight using a pre-established correlation, and terminate the polycondensation of each oligomer at a desired point. The resulting precursor segmented copolymer, equipped with hydroxyl anchoring groups, was converted into a macro-RAFT agent and subsequently grafted with PVDF chains, yielding the final synchronized piezoelectric and luminescence (SPL) copolymer. Among the products, SC-g-PVDF (S), with a smaller PVDF fraction, showed piezoelectric performance (d33 20.7 pm/V) comparable to a random-type PVDF-grafted copolymer and achieved over 20% higher electroluminescence brightness.Graphic AbstractA segmented polyfluorene copolymer grafted with poly(vinylidene fluoride) chains and an LED device fabricated using this piezoelectric and luminescent material.

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