Synthesis and self-assembly of brush-shaped block copolymer structure via ATRP and ROP

Well-controlled brush-shaped block copolymers (BBCPs) of high molecular weight with polystyrene (PS) and polylactic (PLA) side chains, (poly (cis-5-norbornene-exo-2,3-dicarboximide-end poly (styrene)))-block-(poly (cis-5-norbornene-exo-2,3-dicarboximide-end poly (lactide))) (PNB-g-PS)-b-(PNB-g-PLA) were synthesized by combining atom transfer radical polymerization (ATRP) and ring opening polymerization (ROP). The synthesis of the (PNB-g-PS)-b-(PNB-g-PLA) was well-controlled with molecular weight and polydispersity index (M-n, (GPC) = 1310000 g mol(-1) and M-w/M-n (GPC) = 1.16). The SEM, XRD and DSC reveal that there are two immiscible cis-5norbornene-exo-2,3-dicarboximide-end poly(styrene) (NB-PS) and cis-5-norbornene-exo-2,3-dicarboximide-end poly(lactide) (NB-PLA) phases in BBCP after self-assembly, which leads to partial crystallization. Moreover, the effect of the self-assembly temperature on morphology and reflectance of (PNB-g-PS)-b-(PNB-g-PLA) has been investigated. These (PNB-g-PS)-b-(PNB-g-PLA) exhibit obvious pearlescent appearance and wide band reflection after heat-treated at different temperatures (120 degrees C, 130 degrees C, 140 degrees C and 150 degrees C). Besides, with the increase of the self-assembly temperature, the domain spacing of (PNB-g-PS)-b-(PNB-g-PLA) decreases and the reflectance in visible range of (PNB-g-PS)-b-(PNB-g-PLA) increases. However, the self-assembly temperature does not significantly influence the reflection wavelength range of (PNB-g-PS)-b-(PNB-g-PLA).