Find in Library

Polylactides (PLAs) are thermoplastic materials known for their wide range of applications. Moreover, the equimolar mixtures of poly(L-Lactide) (PLLA) and poly(D-Lactide) (PDLA) can form stereocomplexes (SCs), which leads to the formation of new non-covalent complex macromolecular architectures. In this work, we report the synthesis and characterization of non-covalent triblock terpolymers of polystyrene-<i>b</i>-stereocomplex PLA-<i>b</i>-poly(2-vinylpyridine) (PS-<i>b</i>-SC-<i>b</i>-P2VP). Well-defined <i>ω</i>-hydroxy-PS and P2VP were synthesized by “living” anionic polymerization high-vacuum techniques with <i>sec</i>-BuLi as initiator, followed by termination with ethylene oxide. The resulting PS-OH and P2VP-OH were used as macroinitiators for the ring-opening polymerization (ROP) of DLA and LLA with Sn(Oct)₂ as a catalyst to afford PS-<i>b</i>-PDLA and P2VP-<i>b</i>-PLLA, respectively. SC formation was achieved by mixing PS-<i>b</i>-PDLA and P2VP-<i>b</i>-PLLA chloroform solutions containing equimolar PLAs segments, followed by precipitation into <i>n</i>-hexane. The molecular characteristics of the resulting block copolymers (BCPs) were determined by ¹H NMR, size exclusion chromatography, and Fourier-transform infrared spectroscopy. The formation of PS-<i>b</i>-SC-<i>b</i>-P2VP and the effect of molecular weight variation of PLA blocks on the resulting polymers, were investigated by differential scanning calorimetry, X-ray powder diffraction, and circular dichroism spectroscopies.