Kinetics and thermodynamics analysis for ring-opening polymerization of ε-caprolactone initiated by tributyltin n-butoxide using differential scanning calorimetry

Abstract

The bulk ring-opening polymerizations (ROP) of e-caprolactone (e-CL) initiated by synthesized tributyltin n-butoxide (nBu 3 SnOnBu) initiator were conducted at 120°C and the molecular mass and polydispersity index of poly(e-CL), PCL, were determined. The coordinationinsertion ROP of e-CL was confirmed by 1 H-NMR. The molecular mass of PCL was successfully controlled with monomer to initiator concentration ratio. The kinetics and thermodynamics of ROP were investigated by differential scanning calorimetry (DSC) using both non-isothermal and isothermal methods. From the non-isothermal method, the activation energy (E a ) of ROP of e-CL initiated by 1.0, 1.5, and 2.0 mol% of nBu 3 SnOnBu was derived from the method of Kissinger (78.3, 61.1, and 59.9 kJ mol -1 ) and Ozawa (82.8, 66.2, and 64.9 kJ mol -1 ). For isothermal method, the values of E a for these three concentrations of nBu 3 SnOnBu were 74.2, 65.8, and 62.0 kJ mol -1 , respectively. The first-order reaction model was employed to determine the apparent rate constant (k app ). The degree of aggregation (m) of nBu 3 SnOnBu in e-CL was also determined using isothermal method which confirmed its nonaggregated form. In addition, the activation enthalpy (DH = ) and entropy (DS = ) were estimated to be 70.5 kJ mol -1 and -100.3 J mol -1 K -1 by isothermal DSC. The Friedman, Kissinger-Akahira-Sunose, and Flynn-Wall-Ozawa isoconversional methods were also applied to non-isothemal DSC data to investigate the dependence of E a with monomer conversion (a). The results of all three methods were discussed and compared with isothermal and non-isothermal methods at 1.0 mol% of nBu 3 SnOnBu. The overall results demonstrate that DSC is a fast, convenient, and reliable method for studying the kinetics and thermodynamics of ROP of e-CL initiated by nBu 3 SnOnBu.

Ring-opening copolymerization thermodynamics and kinetics of γ-valerolactone/ϵ-caprolactone

“…Commonly, E a is calculated with semi-empirical methods, based on maximum reaction rate or isoconversional maps. Although these methods have been used to study ROP of ECL [ 38 – 41 ], they present some restrictions that may limit their reliability. For the reported case, we performed a mathematical modeling of experimental data, avoiding approximations or model restrictions.…”

Use of non‐isothermal DSC in comparative studies of tin(II) systems for the ring‐opening polymerization ofd‐lactide

“…The slope of a plot of polymerization rate [ln( β /)] against 1000/ T p at constant conversion enables the determination of E a at each conversion. Whereas this method employs the Murray and White approximation for the temperature integral, no approximation is used in the method of Friedman 28, 30, 32, 33 . Thus, the E a values can be directly determined from the slope of a plot of ln(d α /d t ) against 1000/ T p according to Eqn (): where i refers to data for a given heating rate.…”

“…With its allowing rapid determination and continuous kinetic evaluation, it is suitable for a comparative study of the reactivities of various monomers or the efficiencies of initiating systems. [26][27][28][29][30][31][32][33] The effects of the initiator concentration and temperature on the kinetic and thermodynamic parameters for the ROP of L-lactide 31 and ϵ-CL 32 using Sn(Oct) 2 and nBu 3 SnOnBu were investigated using nonisothermal and isothermal DSC methods. Meelua et al 30 and Limwanich et al 33 utilized DSC for the ROP of ϵ-CL using Ti(IV)OR (R = nPr, nBu, tBu and 2-ethylhexyl) and tributyltin alkoxide (nBu 3 SnOR; R = Me, Et, nPr and nBu) as initiators, respectively, in order to describe the steric influence of the alkoxide group on the rate of polymerization.…”

Amino-Functionalized Multiwalled Carbon Nanotubes Lead to Successful Ring-Opening Polymerization of Poly(ε-caprolactone): Enhanced Interfacial Bonding and Optimized Mechanical Properties

“…Differential scanning calorimetry (DSC) measurements were carried out in a calibrated Setaram DSC (model 141) in order to monitor in situ polymerization . From each mixture, a 15 ± 1 mg sample was placed in stainless-steel sealed crucibles, whereas an identical empty crucible was used as reference in each measurement.…”

“…Differential scanning calorimetry (DSC) measurements were carried out in a calibrated Setaram DSC (model 141) in order to monitor in situ polymerization. 61 From each mixture, a 15 ± 1 mg sample was placed in stainless-steel sealed crucibles, whereas an identical empty crucible was used as reference in each measurement. The samples were heated from ambient temperature (25 °C) to 250 °C under a 50 mL/ min flow of N 2 with heating rates of 1, 2.5, and 5 °C min polymerization was calculated by the isoconversional method of Starink.…”