Table 1.
Ring-opening polymerization of rac- and L-LA promoted by (NSO)AlMe2/iPrOH.
| Run (a) | Mon. | [Mon]/[Al] | T [°C] |
t [h] |
Conver. [%] (b) |
TOF [h−1] (c) |
Mn(th) [kg/mol] (e) |
Mn(exp) [kg/mol] (f) |
PDI (f) |
|---|---|---|---|---|---|---|---|---|---|
| 1 | L-LA | 100 | 80 | 7 | 81 | 12 | 5.8 | 5.6 | 1.08 |
| 2 | rac-LA | 100 | 80 | 3 | 81 | 27 | 5.8 | 5.8 | 1.22 |
| 3 | rac-LA | 100 | 90 | 1.5 | 80 | 53 | 5.8 | 4.3 | 1.46 |
| 4 | rac-LA | 100 | 100 | 1.5 | 94 | 63 | 6.8 | 4.3 | 1.53 |
| 5 | rac-LA | 500 | 80 | 4 | 86 | 107 | 30.9 | 28.7 | 1.36 |
| 6 | rac-LA | 1000 | 80 | 16 | 78 | 49 | 56.7 | 52.4 | 1.41 |
| 7 (d) | rac-LA | 1000 | 190 | 0.08 | 56 | 563 | 40.3 | 38.9 | 1.07 |
| 8 (d) | L-LA | 1000 | 190 | 0.08 | 52 | 522 | 37.5 | 16.2 | 1.30 |
(a) All reactions were carried out in 2.0 mL of toluene as solvent, [Al]0 = 14 mM, [LA] = 1.4 M, [LA]0/[iPrOH]0/[cat]0 = 100/2/1; (b) Molecular conversion determined by 1H NMR spectroscopy (CDCl3, 298 K); (c) TOF = molMon × conversion/(molAl × h); (d) Polymerization without solvent; (e) Calculated molecular weight using Mn(th) = (144.13 × ([LA]0/[iPrOH]0) × conversion)/1000; (f) Experimental molecular weight Mn(exp) and polydispersity index (PDI) determined by GPC in THF using polystyrene standards and corrected using factor 0.58.