The Role Of Liquid Crystalline Side Chains For Long-Range Ordering In The Block Copolymer Thin Films

In this study, side chain liquid crystalline (SCLC) fluorinated functionalities capable of controlling the orientation of the block copolymer (BCP) domains in thin film were successfully demonstrated. By introducing 1H,1H,2H,2H-perfluorodecanethiol onto a precursor polymer to obtain a novel BCP with a C8F17-containing LC side chain, BCP domains in 6.3-36.3 nm scale were obtained. For the studied symmetric SCLC diblock copolymers, a morphology transition from lamellae to cylinder was observed with reduced molecular weight (M-n). A co-existed 3.6 nm periodicity from lamellar smectic phase of SCLC was also verified in all synthesized BCPs of varied M-n, by comprehensive characterizations of small angle X-ray scattering (SAXS) and wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and polarized optical microscopy (POM). Atomic force microscopy (AFM) of the thin films revealed the formation of fingerprint patterns with increased correlation length when the domain spacing of the BCP is closer to the periodicity of the smectic structures, which are supported by the quantitative analysis on AFM images.