HCl-Catalyzed Polymerization of Benzoxazine and Chemical Transformations along Pyrolysis to Microporous Carbons in Advanced and Emerging Polybenzoxazine Science and Technology

HCl-Catalyzed Polymerization of Benzoxazine and Chemical Transformations along Pyrolysis to Microporous Carbons in Advanced and Emerging Polybenzoxazine Science and Technology Report Title This chapter describes a room-temperature HCl-catalyzed synthesis of polybenzoxazine aerogels from bisphenol A, formaldehyde and aniline that cuts the typical multi-day high-temperature (?130 oC) route to a few hours. In addition to the ortho-position of the phenol, the HCl-process engages the para-position of the aniline moieties leading to a higher degree of crosslinking, which, in turn leads to smaller particles, higher mesoporosity, higher surface areas and lower thermal conductivity than the thermal route. The carbonization efficiency (up to 61% w/w), as well as the nanomorphology and the pore structure of pyrolytically derived C-aerogels depend critically on a curing step of asprepared polybenzoxazne aeroges at 200 oC in air, which oxidizes the -CH2brdges along the polymeric backbone and subsequently fuses the rings of phenol and aniline. C-aerogels from cured polybenzoxazine aerogels are microscopically similar to their respective parent aerogels, however, they have greatly enhanced surface areas, up to 520 m2/g (from ?70 m2/g in the parent aerogels) with up to 83% of that new surface area attributed to newly created micropores. Applications reviewed are specific to those findings and include synthesis of iron oxide/polybenzoxazine interpenetrating networks as precursirs of iron(0) aerogels, and use of microporous carbons for CO2 sequestration.