Synthesis and characterization of polylactide–poly(methyl methacrylate) copolymer by combining of ROP and AGET ATRP

Block copolymers of polylactide (PLA) and poly(methyl methacrylate) (PLA–PMMA) were synthesized by the combination of ring-opening polymerization (ROP) and activator generated by electron transfer for atom transfer radical polymerization (AGET ATRP), where PLA was prepared as macroinitiator with active bromo end group (PLA–Br). Tin octoate (Sn(oct)2) and benzyl alcohol were applied as the initiation system for ROP of lactide. During AGET ATRP, copper (II) chloride (CuCl2) with N,N,N′,N″,N″-pentamethyl-diethylenetriamine (PMDETA) was used as the catalyst system including Sn(oct)2 as reducing agent. At the feed ratio [PLA–Br]/[CuCl2]/[PMDETA]/[Sn(oct)2]/[MMA] of 1/1/9.6/0.45/100, the mole fraction of the PMMA block was 0.6 as determined by 1H NMR. Thermal stability of PLA was enhanced by incorporating of PMMA as block copolymers. In addition, blend between of PLA and PLA–PMMA copolymer was investigated and 5 phr of PLA–PMMA showed optimum condition to decrease in Young's modulus and increase in impact strength.