Abstract
Self-assembly of block copolymers (bcps) has attracted considerable attention due to their versatile applications for nanotechnology. Among the wide variety of bcp systems, the rod-coil bcp composed of a rod and a coil block has received intensive interest owing to the complex phase structure prescribed by the large disparity of the flexibility of the constituting blocks as well as the strong self-organization driving force of the rod block. In addition to the conventional parameters such as segregation strength and constituent volume fraction, molecular architecture offers another important parameter for tuning the self-assembled structure of bcp. In this work, we systematically study the self-assembly behavior of the rod-coil block copolymers composed of poly(3-hexylthophene) (P3HT, A blok) as the rod and poly(ε-caprolactone) (PCL, B block) as the coil .The bcp systems studied bear the molecular architecture of AB, AB2, BAB and B2AB¬¬2. The crystallization kinetics of the PCL block was found to depend strongly on the molecular architecture; moreover, the architecture also influenced the interdomain distance of the microphase-separated structure, which was explained by considering the packing mode of the B block in the microdomains. To further explore the phase transition mechanism, temperature-dependent simultaneous SAXS and WAXS experiments were conducted. The results indicated the microphase separation always occurred before the crystallization of P3HT block in the cooling cycle. Moreover, the crystallizations of P3HT and PCL block were largely confined in the microdomains constructed by the microphase separation.