DSC Kinetics Analysis for the Synthesis of Three‐Arms Poly(ε‐caprolactone) Using Aluminum Tri‐sec‐Butoxide as Initiator

Abstract

ABSTRACTThe kinetics of the ring‐opening polymerization (ROP) of ε‐caprolactone (ε‐CL) initiated by soluble aluminum tri‐sec‐butoxide (Al(OsecBu)3) has been investigated by the differential scanning calorimetry (DSC). The DSC polymerizations were carried out under nonisothermal and isothermal conditions to obtain three‐arms poly(ε‐caprolactone) (PCL). From nonisothermal DSC, the polymerization rate (dα/dt) increased with increasing heating rates. The values of Ea were determined from Kissinger ( kJ mol−1), Friedman (31.0 – 63.0 kJ mol−1), and Starink (64.0 – 71.0 kJ mol−1) methods. From isothermal DSC, the dα/dt and the apparent rate constant (kapp) increased with increasing polymerization temperatures. The ROP of ε‐CL initiated by Al(OsecBu)3 occurred via the coordination insertion mechanism. The number average molecular weight () and percent yield of the synthesized PCL was enhanced by increasing polymerization temperature. The synthesized PCL with of 2.4 × 104 was obtained using a molar ratio of monomer to Al‐O active center ([M]/[Al‐O]) of 400 at 150ºC for 24 h. Al(OsecBu)3 is one of the promising initiator due to its solubility, low transesterification reaction, and high efficiency in ε‐CL polymerization.