Examining thermal stability and structure property relationships in coatings based on linear aromatic poly(methoxy-thiocyanurate)s

A series of copoly(methoxy-thiocyanurate)s is prepared in good yield and purity, and fully characterised. Many of the resulting polymers, formed at room temperature using phase transfer catalysis, can be cast into films with good resilience and thermal stability (some examples suffer practically no mass loss when held isothermally at 190 °C and only display appreciable losses when held continuously at 225 °C). Char yields of 61-64% are achieved in nitrogen depending on backbone structure. Some problems were encountered with solubility, particularly with copolymers, which limited molecular weights analysis, but values of M<inf>n</inf> = 7000-10,000 g mol^-1 were obtained for the polycyanurate and polythiocyanurate homopolymers. DSC reveals polymerisation exotherms with maxima at 197-207 °C (ΔH<inf>p</inf> = 39-48 kJ/mol), which are believed to be due to isomerisation of the (activation energies span 172-205 kJ/mol), since X-ray powder diffraction measurements reveal no evidence of crystalline structure in the resulting product.