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

• Published in: Designed monomers and polymers Vol. 24; no. 1; pp. 89 - 97
• Main Authors: Punyodom, Winita, Limwanich, Wanich, Meepowpan, Puttinan, Thapsukhon, Boontharika
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis 01.01.2021; Taylor & Francis Ltd; Taylor & Francis Group
• Subjects: Bulk polymerization; Chemical synthesis; Differential scanning calorimetry; DSC; Full Length; Kinetics; Polymerization; Ring opening polymerization; Tin; tin(II) octoate; ε-caprolactone; Kinetics; ε-caprolactone; DSC; tin(II) octoate; ring-opening polymerization
• ISSN: 1385-772X; 1568-5551; 1568-5551
• DOI: 10.1080/15685551.2021.1908657

The kinetics of ring-opening polymerization (ROP) of ε-caprolactone (ε-CL) initiated by 1.0, 1.5 and 2.0 mol% of stannous(II) octoate/n-hexanol (Sn(Oct) 2 /n-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 ε-CL were calculated using differential (Friedman) and integral isoconversional methods (Kissinger-Akahira-Sunose, KAS). The average activation energy (E a ) 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 (A) were determined from model fitting method using Avrami-Erofeev reaction model. The average values of A for the ROP of ε-CL initiated by 1.0, 1.5 and 2.0 mol% of Sn(Oct) 2 /n-HexOH (1:2) were 7.3x10 7 , 2.8x10 6 and 1.2x10 6 min −1 , respectively. From kinetics studied, the polymerization rate of ε-CL increased with increasing initiator concentration. The performance of Sn(Oct) 2 /n-HexOH in the synthesis of poly(ε-caprolactone) (PCL) was investigated by bulk polymerization at temperatures of 140, 160 and 180 °C. Sn(Oct) 2 /n-HexOH (1:2) could produce high number average molecular weight ( = 9.0 × 10 4 g/mol) and %yield (89%) of PCL in a short period of time at Sn(Oct) 2 concentration of 0.1 mol% and temperature of 160°C. The mechanism of the ROP of ε-CL with Sn(Oct) 2 /n-HexOH was proposed through the coordination-insertion mechanism.