Mechanochemical reactivity or degradability of the cyclic polymers differentiated from the linear polymers are interesting fields. We explored the degradation kinetics of the monodisperse polylactides having linear or cyclic conformations. Polymer series of a broad range of targeted DPs were prepared from iterative convergent strategy, selective click chemistry, and elaborate purification strategy. Systematic analysis of the degradation kinetics was conducted for solution- and solid-state using ultrasonication (US) and ball-mill grinding (BMG), respectively. At the same DPs, the cyclic polymers showed slower degradation, presumably due to the shorter extended length than linear polymers for both US and BMG. However, their degradation profiles were different depending on the degradation conditions. In solution-state, we found much faster scission of the linear polymers (or linear intermediates) than the cyclic polymers of the same DPs, so it was hard to observe significant amounts of the intermediates originating from the cyclic polymers. In contrast, in the solid-state, the linear and cyclic polymers showed comparable degradation rates, so we could easily observe the generation of the linear intermediates. Degradation of the cyclic polymers with prefluorescent radical traps further supported the stepwise scissions in the cyclic polymer degradation and different degradation profiles depending on the US and BMG.

Mechanochemical degradation of monodisperse cyclic polymers: Shedding the light on the dynamic memory effect

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