Chain scission by ultrasonication of polycaprolactone with different initial molecular weight and concentration

Ultrasonication-mediated scission of three commercially available polycaprolactone (PCL) with different initial molecular weights (designated as low-, intermediate- and high-IMW PCL) was investigated. Each IMW PCL solution at different concentrations were subjected to sonication intervals. Scission-induced molecular size reduction, polydispersity index alteration, and a limiting molecular weight of the sonicated PCL samples depend on their initial molecular weight and effective concentration, whereby interaction forces play an important role. epsilon-caprolactone was identified post-scission event. It is hypothesized that a single scission event occurs at the upward/downward vicinity to the mid-point of the chain involving unzipping mechanism, driven by known forces associated with sonication energy dissipation. Further scission event of the generated fragment is no longer feasible below a limiting molecular weight for the designated IMW PCL.

Automated summary

Ultrasonication was used to study the scission of different commercially available polycaprolactone (PCL) with varying initial molecular weights. The results showed that the size reduction and polydispersity index changes of the sonicated PCL samples depended on their initial molecular weight and effective concentration. The scission event involved an unzipping mechanism driven by forces associated with sonication energy dissipation. Further scission of the generated fragments was no longer possible below a limiting molecular weight for the designated PCL.