3,5-Dimethylphenol resole resins: their structure and mechanism of thermal decomposition leading to graphitisation

Novel model compounds based on 3,5-dimethylphenol were used to determine the structure of graphitisable 3,5-dimethylphenol resins. The base catalysed reaction of 3,5-dimethylphenol with formaldehyde was found to give a solid, which CP-MAS 13C NMR showed to have a predominately linear structure, highly condensed but with few crosslinks. Model studies showed that the 3,5-dimethylphenol material was readily able to form xanthene type structures, unlike phenol derived material. The presence of xanthene structures can account for the unusual properties of 3,5-dimethylphenol derived resins, including oxygen sensitivity and graphitisability.