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Versatility of Bisphenol-Based Polybenzoxazine Networks

Austin D. Baranek, Laken L. Kendrick, Jananee Narayanan, Ginger E. Tyson, Steven Wand, Derek L. Patton

Abstract


In this paper, we report the synthesis of a series of novel aliphatic-bridged bisphenol-based benzoxazine monomers comprising four to ten methylene unit spacers (BZ(n)BA). Cationic ring-opening polymerization of these monomers provides flexible polybenzoxazine thermosets with good film forming characteristics under solvent-free processing conditions. The effects of aliphatic bisphenol chain length on polymerization behavior, thermomechanical transitions, and mechanical properties of the polybenzoxazine thermosets are reported. Thermomechanical properties of the pBZ(n)BA thermosets, such as rubbery storage modulus and glass transition temperature (Tg), show a strong dependence on the length of the aliphatic-bridged bisphenol linker where both properties decrease with increasing linker length. In particular, changing the length of the aliphaticbridged bisphenol linker enables tailoring the Tg of the pBZ(n)BA series from 67 °C to 101 °C, as determined by dynamic mechanical analysis (DMA). Moreover flexible bisphenol-based polybenzoxazines are demonstrated as a viable anion exchange membrane material showing exceptional conductivity for a variety of counter ions. Conductivity also shows a strong dependence on crosslink density wherein a densely crosslinked material restricts movement of ions.

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