Ring-opening Polymerization Reaction Mechanism of ε-Caprolactone Catalyzed by Bis(dibenzoylmethanato) zirconium(IV) Using PM3 Semi-Empirical Method

Polycaprolactone (PCL) is a semi-crystalline polymer and belongs to a
biodegradable plastic. PCL also can naturally degraded, has a high degree of adjustment with
other polymer, and has great mechanical and thermal properties. By using the Lewis acid
catalyst, PCL can be yielded through the ring opening polymerization (ROP) of caprolactone
(ɛ-CL). The objective of this study was to explore the most likely reaction mechanism of the
ROP of ε-CL using bis(dibenzoylmethanato) zirconium(IV) chloride as a catalyst. Here, the
Hyper Chem 8.0 program was performed to compute the monomer molecule, intermediate
molecules, and polymer molecule. The program can be launch on the Windows 07 systems.
The method used was the PM3 semi-empirical method. This program also used to show the
results of optimized structures. The calculation results show that to generate PCL required
bis(dibenzoylmethanato) zirconium (IV) catalyst. The ROP reaction mechanism of ε-CL can be
occurs through direct coordination ɛ-CL on the Zr complex. After that, deprotonation and
insertion monomer. Last step was chain propagation of the ɛ–CL