Synthesis of a triptycene-containing dioxazine benzoxazine monomer and a main-chain triptycene-polydimethysiloxane-benzoxazine copolymer with excellent comprehensive properties

Abstract

A novel triptycene-containing dioxazine benzoxazine monomer (TB-al) and a main-chain triptycene-containing dioxazine benzoxazine copolymer (poly(triptycene-containing dioxazine benzoxazine-co-polydimethylsiloxane), TB-al-co-PDMS) have been synthesized and fully characterized. Polymerization of the monomer, TB-al, and the copolymer, TB-al-co-PDMS, was studied by in situ FT-IR and DSC. Fire-related properties and thermal stability of the resulting thermosets were evaluated by TGA and micro-scale combustion calorimetry (MCC). The obtained thermosets, poly(TB-al) and poly(TB-al-co-PDMS), exhibit outstanding thermal stability with T_d10 values of 320 and 450 °C, char yields of 44 and 72% at 800 °C, low flammability as determined by HRC, affording values of 69.6 and 31.6 J g⁻¹ K⁻¹, and THR values of 10.5 and 9.4 kJ g⁻¹, respectively. Remarkably, poly(TB-al-co-PDMS) presents excellent dielectric performance with a dielectric constant of 2.37 at 1 MHz and good hydrophobicity revealed by the low water uptake value of 0.056% after 120 h of sample immersion in water at room temperature. The combined properties and advantages of these triptycene-based thermosets (poly(TB-al) and poly(TB-al-co-PDMS)) clearly indicate their great potential for applications in the field of high-performance polymers.