Mechanism of chain propagation for the synthesis of polyoxymethylene dimethyl ethers

Polyoxymethylene dimethyl ethers (PODE) were synthesized from the reaction of paraformaldehyde with dimethoxymethane (DMM) over different acid catalysts at different conditions. Products were found to follow the Schulz-Flory distribution law. The chain propagation proceeds through the insertion of an individual segment of CH2O one by one, while the simultaneous insertion of a few CH2O segments or their assembly is unlikely. Due to the restriction of this law, it is difficult to increase the selectivity to the desired products (e.g., PODE3-4).