Polylactic acid macromonomer radical propagation kinetics and degradation behaviourElectronic supplementary information (ESI) available. See 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. Polylactic acid (PLA) macromonomer radical homopropagation rate coefficients are evaluated as a function of average macromonomer chain length. Hydrolysis studies of nanoparticles (NP) produced from PLA macromonomers demonstrate the importance of end-group functionality on NP degradation time.