Synthesis and Characterization of ABA-Type Block Copolymers Based onPoly (L-lactide) via Ring Opening Polymerization (ROP)

초록

The ABA-type block copolymers were synthesized using ROP, employing poly(L-lactide) (PLLA) as the rigid chain and either poly(δ-valerolactone) (PVL) or poly(?- caprolactone) (PCL) as the flexible middle block. The modified initiator's structure was confirmed using FTIR and 1H-NMR. The molar mass of flexible middle block was fixed at 16 kg mol-1 for both PVL and PCL while the molar mass of PLLA end chain was varied from 9 to 40 kg mol-1. The average surface roughness (Ra) were decreased when increasing PLA chain length. Additionally, PCL chains facilitated the formation of more metastable state of PLLA crystals compared to PVL, evident from the DSC thermograms. Upon hydrolytic degradation, PVL and PCL showed weight losses of approximately 74% and 37%, respectively after 3 weeks. The presence of PVL or PCL improved the degradability, making them promising candidates for thermoplastic elastomers (TPEs).