Phase structures of block copolymers blended with small molecules

We report our observations on the influence of blending small molecules on the phase structures of a block copolymer (BCP) system. Poly(styrene-b-4vinyl pyridine) (PS-b-P4VP) BCP was blended with 4-(3,4,5-tris(alkyloxy)benzoyloxy)phenyl 4- hydroxyphenyl isophthalate (BCLCn where n = 6-16) small molecule in different weight ratios. The terminal hydroxyl group of the BCLC is expected to form hydrogen bonding with the P4VP and thus alter the phase structure of the BCP. Thermal analysis, X-ray analysis and transmission electron microscopy were conducted and it was observed that BCLCs with n = 6 and 8 did not have any influence on the BCP morphology and those with n = 14 and 16 have phase separated. There was a substantial decrease in the d-spacing of BCPs blended with BCLCs with n = 10 and 12 and a bilayer structure was evident.