Effect of tributyltin alkoxides chain length on the ring-opening polymerization of ϵ-caprolactone: Kinetics studies by non-isothermal DSC

•We firstly report the kinetics parameters of Bu3SnOR in the ROP of ϵ-CL using DSC.•The increasing of alkoxy (OR) chain length reduces the reactivity of Bu3SnOR.•The reactivity of Bu3SnOMe > Bu3SnOEt > Bu3SnOnPr > Bu3SnOnBu.•Molecular weight of PCL increases with increasing OR chain length of Bu3SnOR.

The kinetics of ring-opening polymerization (ROP) of ϵ-caprolactone (ϵ-CL) initiated by 1.0 mol% of the tributyltin alkoxides (Bu3SnOR; R = Me, Et, nPr and nBu) was investigated by non-isothermal DSC technique. The DSC curves showed the dependency of polymerization exotherms with the heating rate. The polymerization rate increased with increasing of heating rate for all initiating systems. The values of activation energy (Ea) obtained from the peak method of Kissinger for Bu3SnOMe, Bu3SnOEt, Bu3SnOnPr and Bu3SnOnBu initiated ROP of ϵ-CL were 52.4, 70.3, 75.9 and 78.0 kJ/mol, respectively. The values of Ea increased with increasing of alkoxy chain length but polymerization rate decreased. The variation of Ea with monomer conversion was investigated by Friedman and Starink isoconversional methods. The Bu3SnOnBu initiator produced the highest molecular weight and %yield of poly(ϵ-caprolactone) (PCL).

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