Boron-containing arylacetylene polymers as a novel carbon precursor: Synthesis, thermal curing and carbonisation

•A novel boron-containing carbon precursor was synthesised.•An aromatic ring is formed by the curing reaction of the triple bond.•The char yield of the cured PBA is up to nearly 80% at 900 °C.•The boron is bonded to carbons, which promotes the carbon atoms from sp3 to sp2.

A novel boron-containing carbon precursor with high yield and crystallisation (i.e., boron-containing arylacetylene polymers (PBAs)) was synthesised by the polycondensation reaction between arylethynyl Grignard reagent and boron trichloride-pyridine complexes. The precursor structures, curing behaviour and carbonisation were investigated. An aromatic ring is formed by polymerisation of a triple bond during the curing reaction of PBAs, which resulted in a significantly higher char yield (i.e., as high as nearly 80%) at 900 °C for the cured PBAs. The boron is chemically bonded to carbons of the PBAs precursor, which reduces the activation energy of the dissociation and rearrangement of the carbon–carbon bonds and promotes the change in the hybridisation of carbon atoms from sp3 to sp2.

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