Chapter 5 Kinetics of Aldehyde Polymerization

Abstract

This chapter discusses the polymerization of formaldehyde, higher aliphatic aldehydes, and haloaldehydes with particular emphasis on the kinetics of polymerization. The kinetics of aldehyde polymerization have not been studied as extensively as the kinetics of more conventional polymerizations, for example, the free radical bond opening polymerizations of styrene, vinyl chloride or methylmethacrylate or the ring opening polymerizations of tetrahydrofuran or ethylene oxide. The chapter presents an important point in aldehyde polymerization, the problem of precipitation or crystallization of the polymer during polymerization. In all cases of aldehyde polymerization where crystalline polymers are formed, in formaldehyde polymerization and higher aldehyde polymerization to isotactic polymers, precipitation occurs during the polymerization. Rapid polymerization of acetaldehyde to amorphous polymer is observed with highly active initiators at very low temperatures in solvents where the polymer is not soluble. In solvents of high dielectric constant, (e.g. dimethylformamide), formaldehyde polymerized and polymers were formed in low yield. Such observations demonstrate that the physical state and surface area of the crystallized polymer have a pronounced influence on the progress of polymerization.