Calculations on the mechanism of ion polymerization in the formaldehyde crystal

A number of possible crystal structures of formaldehyde are calculated using an atom—atom scheme in order to explain some phenomena observed in the low-temperature solid-state polymerization of this and related systems. The structures whose molecular packing favours the polymerization are shown to represent local energy minima. Studies of various molecular motions in so calculated crystals support the hypothesis that polymer chains move spontaneously at the propagation stage. Main peculiarities of the solid-state polymerization mechanism are formulated on the basis of the present and previous calculations.