Supramolecular aggregates of linear and star-shaped polylactides with different number of hydroxyl or carboxyl end-groups

In this paper a set of linear and star-shaped polylactides (PLA's) containing a different number of -OH end-groups (1, 2, 4, 6 and 8) were synthesized. To compare the extent of interactions between different end-groups, the OH end-groups were transformed to COOH end-groups. To attain the proper conditions of this transformation, the conditions were optimized for the chosen model and then used for all synthesized polymers. The structure of synthesized polymers were confirmed by SEC-MALS, NMR and ATR FT-IR analyses. It was shown that PLA's architecture and number of OH and COOH groups in a single macromolecule have an influence on a viscosity of their solution due to their self-organization. For star-shaped PLA's containing higher than four number of COOH end-groups, it has been observed for the first time that the effect of intramolecular interactions exceeds intermolecular interactions what strongly affect their properties in diluted and concentrated solutions.