Dependence of the conformation of nascent poly(oxymethylene) on the conditions of cationic polymerization of trioxane in solution

The conformational structure of nascent poly(oxymethylene) (POM) obtained by cationic polymerization of trioxane in nitrobenzene was investigated by i.r. spectroscopy. It was found that the conformational order of this POM depends considerably on the conditions of preparation. Under conditions of simultaneous polymerization and crystallization, “A” polymer, with long sequences of monomer units in regular G conformation, is obtained. Under conditions of successive polymerization and crystallization, the formation of conformational defects in the helical POM chains is favoured. Then, depending on the supersaturation, we obtained either (a) POM of “B” form with short sequences of monomer units in G conformation, or (b) POM of a mixed type, the i.r. spectrum being describable as a superposition of “A” and “B” spectra. The results indicate that, at comparatively high catalyst concentration, the thermodynamical approach for regulation of supermolecular structure of polymers can be applied successfully for regulation of the conformational order of nascent POM also. At lower concentration of active centres in the polymerizing system, kinetic factors affect considerably the conformational structure of nascent POM.