Polylactic acid macromonomer radical propagation kinetics and degradation behaviour

• Published in: Reaction chemistry & engineering 2017-08, Vol.2 (4), p.487-497
• Main Authors: Rooney, Thomas R., Moscatelli, Davide, Hutchinson, Robin A.
• Format: Article
• Language: English
• ISSN: 2058-9883; 2058-9883
• DOI: 10.1039/C7RE00019G

Polylactic acid ethyl ester methacrylate (PLA N EMA) macromonomers are synthesized with N = 1, 5, 7, and 9 average number of polyester units. While propagation rate coefficients ( k p ) determined by pulsed laser polymerization experiments for bulk PLA 1 EMA and PLA 5 EMA 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 k p measurements. Compared to bulk PLA 5 EMA, the apparent k p 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 PLA 5 EMA 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.