Polylactic acid macromonomer radical propagation kinetics and degradation behaviour†
Polylactic acid ethyl ester methacrylate (PLANEMA) macromonomers are synthesized with N = 1, 5, 7, and 9 average number of polyester units. While propagation rate coefficients (kp) determined by pulsed laser polymerization experiments for bulk PLA1EMA and PLA5EMA are not significantly different over the 40–100 °C temperature range, they are elevated by 60% compared to methyl methacrylate, indicating that the nature of substituents several units beyond the methacrylic group does not decisively impact bulk kp measurements. Compared to bulk PLA5EMA, the apparent kp in 75 wt% n-butanol solution is enhanced due to hydrogen bonding, whereas in 75 wt% dimethylformamide solution it is reduced by 35% because of differences in macromonomer and solvent molar volumes. The PLA5EMA macromonomers are used to produce nanoparticles (NP) by emulsion radical polymerization that degrade almost four times more slowly than NPs produced from their hydroxyl terminated macromonomer counterpart.
- This article is part of the themed collection: CSC100: Celebrating Canadian Chemistry