Synthesis and properties of organo-gels by thiol-benzoxazine chemistry

In the present work, a synthetic strategy based on oxazine-thiol ring-opening reaction for the synthesis of organogels is reported for the first time. For this purpose, main-chain polybenzoxazine (PBZ) was synthesized by the reaction of bisphenol A, 1,6-diaminohexane and paraformaldehyde in toluene:methanol mixture (2:1, v:v). The obtained reactive PBZ was then reacted at room temperature with dithiol compounds in CHCl₃:CH₃OH (1:1, v:v), namely 1,2-ethanedithiol and 1,6-hexanedithiol. The obtained PBZ based gels was characterized by spectral, thermal analysis and uniaxial compression measurements. The influences of the gel preparation conditions on the swelling behavior and the mechanical properties of the resulting gels were investigated. Swelling ratios (J) up to 8.4 in CHCl₃:CH₃OH solution was obtained. Moreover, the curing of the gels was performed over remaining oxazine moieties in the gels and the thermally activated curing was found to be at lower temperatures than that corresponding PBZ.