Jackson, A. W.; Mothe, S. R.; Chennamaneni, L. R.; Herk, A. M. V.; Thoniyot, P., Unraveling the history and revisiting the synthesis of degradable polystyrene analogues via radical ring-opening copolymerization with cyclic ketene acetals. Materials 2020, 13 (10), Article no.: 2325, DOI: 10.3390/ma13102325.
Degradable analogues of polystyrene are synthesized via radical ring-opening (co)polymerization (rROP) between styrene and two cyclic ketene acetals, namely 2-methylene-1,3-dioxepane (MDO) and 5,6-benzo-2-methylene-1,3-dioxepane (BMDO). This approach periodically inserts ester bonds throughout the main chain of polystyrene, imparting a degradation pathway via ester hydrolysis. We discuss the historical record of this approach, with careful attention paid to the conflicting findings previously reported. We have found a common 1H NMR characterization error, repeated throughout the existing body of work. This misinterpretation is responsible for the discrepancies within the cyclic ketene acetal (CKA)-based degradable polystyrene literature. These inconsistencies, for the first time, are now understood and resolved through optimization of the polymerization conditions, and detailed characterization of the degradable copolymers and their corresponding oligomers after hydrolytic degradation.
The Agency for Science, Technology and Research (A*Star), Science and Engineering Research Council,
Specialty Chemicals AME IAF-PP Programme Grant A1786a0030 is thanked for financial support.