Table 1. FTIR Bands Shown in Figure 2ba.
| signal (cm–1) | group | assignment/comments |
|---|---|---|
| 1748 | C=O str. (ester) | ester linkages in depsipeptide and oligoester (polymer) |
| 1709 | C=O str. (carb. acid) | C=O of free glycine and/or lactic acid (monomers) |
| 1652 | amide I (C=O str.) | backbone amide linkages in depsipeptide (polymer) |
| 1539 | amide II (N–H bend) | backbone amide linkages in depsipeptide (polymer) |
| 1479 | –CH3 bend | side chain on lactic acid (both monomer and polymer) |
| 1232 | mixed C–O/C–N str. | carboxylic acid (monomers) and/or 2° amide (polymer) |
| 1184 | C–O str. | ester linkage, C–C–O (polymer) |
| 1117 | C–O str. | free lactic acid (monomer) |
| 1089 | C–O str. | ester linkage, O–C–C (polymer) |
| 1039 | C–CH3 str. | lactic acid (both; also dependent on ATR film thickness78) |
a
Assignments of bands between 1300 and 1000 cm–1 are tentative.