Ring-opening polymerization of -caprolactone initiated by tin(II) octoate/-hexanol: DSC isoconversional kinetics analysis and polymer synthesis.

The kinetics of ring-opening polymerization (ROP) of -caprolactone (-CL) initiated by 1.0, 1.5 and 2.0 mol% of stannous(II) octoate/-hexanol (Sn(Oct)/-HexOH) wase successfully studied by non-isothermal differential scanning calorimetry (DSC) at heating rates of 5, 10, 15 and 20 °C/min. The DSC polymerization kinetic parameters of -CL were calculated using differential (Friedman) and integral isoconversional methods (Kissinger-Akahira-Sunose, KAS). The average activation energy ( ) values obtained from Friedman and KAS methods were in the range of 64.9-70.5 kJ/mol and 64.9-80.4 kJ/mol, respectively. The values of frequency factor () were determined from model fitting method using Avrami-Erofeev reaction model. The average values of for the ROP of -CL initiated by 1.0, 1.5 and 2.0 mol% of Sn(Oct)/-HexOH (1:2) were 7.3x10, 2.8x10 and 1.2x10 min, respectively. From kinetics studied, the polymerization rate of -CL increased with increasing initiator concentration. The performance of Sn(Oct)/-HexOH in the synthesis of poly(-caprolactone) (PCL) was investigated by bulk polymerization at temperatures of 140, 160 and 180 °C. Sn(Oct)/-HexOH (1:2) could produce high number average molecular weight ( = 9.0 × 10 g/mol) and %yield (89%) of PCL in a short period of time at Sn(Oct) concentration of 0.1 mol% and temperature of 160°C. The mechanism of the ROP of -CL with Sn(Oct)/-HexOH was proposed through the coordination-insertion mechanism.