Copolymers containing two types of reactive groups: New compatibilizer for immiscible PLLA/PA11 polymer blends

While reactive compatibilization has been widely used, both the compatibilization efficiency and the varieties still need further enhancements. Herein, we demonstrated a novel “Dual-reactive compatibilization” strategy using a compatibilizer containing bifunctional groups. It was shown that the compatibilizer containing two types of reactive groups shows higher compatibilization efficiency as compared with traditional compatibilizer with only one type of reactive groups. Specifically, a series of poly(styrene-co-(glycidyl methacrylate)-co-(maleic anhydride)) ternary copolymers (SGM) containing both reactive epoxide groups and maleic anhydride groups were synthesized and then incorporated into the immiscible poly(amide 11)/poly(l-lactic acid) (PA11/PLLA) blend. The terminal amino groups of PA11 are ready to react with the maleic anhydride groups of the SGM while the carboxyl groups of PLLA react with the epoxide groups of SGM. Double-grafted copolymers with both PA11 and PLLA chains were in-situ formed and located along the PA11-PLLA interface, in which the grafted PLLA chains were buried in PLLA phase while the grafted PA11 chains were immersed in PA11 phase. Thus the compatibility of PA11/PLLA was significantly improved. In addition, the effect of SGM structure on compatibilization efficiency was investigated. The PA11/PLLA (50/50) blends with 3 wt % specific compatibilizer (P(S93-G5-M2)) show the elongation at break and tensile strength of 411% and 57.9 MPa, respectively, the highest values reported so far for the blends. This work provides a new strategy to compatibilize immiscible polymer blends (especially the blends of engineering plastics containing reactive groups). Moreover, the novel bifunctional reactive compatibilizers are also ready for large-scale industrial applications.