Polymerization of adsorbed monolayers. II. Thermal degradation of the inserted polymer

Monomolecular layers of methyl methacrylate inserted between the lamellae of montmorillonite clay were polymerized. Finely divided complexes of poly(methyl methacrylate)–montmorillonite were suspended in boiling hydrocarbons and subjected to thermal degradation at 215°C. and above, under air and nitrogen, with constant vigorous stirring. Aliquots were regularly withdrawn, centrifuged, and extracted with appropriate solvents. The weight losses upon calcination at 1000°C. were determined, and from them the rates of reversal to monomer were followed. Complexes containing inserted and external polymer were studied. The inserted polymer was found to resist thermal degradation under conditions at which complete degradation of the external polymer was found. This effect seems to be due to steric factors hindering the thermal motion of the segments of the polymer sandwiched between the lamellae of the crystallites. The insertion polymer isolated from the polymer–clay complex, had a greater thermal stability than poly(methyl methacrylate) made in a conventional free radical system without the presence of clay.