Table 3.
Influence of catalyst on molecular weight and Tg of PIsSu
| Catalyst | n (catalyst) [mol%]* | ppm (metal) | Mn [kg/mol] | PDI | Tg [°C] |
|---|---|---|---|---|---|
| / | / | / | 3.7 | 2.1 | 70 |
| BuSnOOH | 0.1 | 520 | 40.4 | 2.4 | 82 |
| BuSnOOH | 0.05 | 260 | 34.7 | 2.2 | 82 |
| Ti(OBu)4a | 0.1 | 210 | 33.0 | 2.2 | 83 |
| Ti(OBu)4a | 0.05 | 105 | 28.7 | 2.1 | 81 |
| Zr(OBu)4 | 0.1 | 400 | 3.7 | 2.1 | 79 |
| Zn(OAc)2 | 0.1 | 287 | 1.7 | 2.1 | 72 |
| GeO2 | 0.1 | 318 | 1.5 | 2.0 | 59 |
Reaction conditions (unless noted otherwise): Reactions were conducted on a 60 mmol scale (respective diacid), with a 1:1:1.5 molar ratio of isosorbide:succinic acid:p-cresol and the indicated catalyst. Esterification was conducted for 5 h at 240 °C. For pre-polycondensation, the temperature was decreased to 220 °C and the pressure reduced from atmospheric pressure to 0.4–0.8 mbar within 2 h. Polycondensation was conducted for 1 h at 220 °C and 0.4–0.8 mbar.
*Mol% respective diacid.
aCatalyst was added in two portions to compensate for hydrolytic sensitivity of Ti-alkoxides.