Degradable Polyacetals/Ketals from Alternating Ring-Opening Metathesis Polymerization

We report the synthesis of degradable polyacetals and polyketals with controlled molecular weights and low dispersities using alternating ring-opening metathesis polymerization (AROMP) of 1,1-disubstituted cyclopropenes and dioxepins. Under optimized conditions, high degrees of alternation and controlled polymerization were achieved between nonpropagating cyclopropenes and low-strain dioxepins. The high degrees of alternation allowed the resulting polymers to fully degrade into small molecules under acidic conditions at variable rates depending on the acetal/ketal structures. This synthetic strategy illustrates the use of AROMP to incorporate functionalities into both the polymer backbone as well as the side chains.