Role of each part of cyanobiphenyl-containing polymers in porous-film preparation by using the breath-figure method

ABSTRACT

The breath-figure method using the condensation of water droplets can easily fabricate regular porous films. Although the method is simple, the phenomenon itself requires the control of many parameters that change throughout the process. Therefore, we require a unified understanding of polymers for the fabrication of ordered porous films. In this study, to clarify the required molecular structures of polymers to form a regular porous structure, we systematically explored poly(methacrylate)s with cyanobiphenyl moieties connected by dodecyl groups in the side chain (P11CB); these could form a hexagonal ordered porous structure on the entire film surface. The comparison of P11CB and P11B, which is a P11CB without cyano groups, showed that the local polar groups in hydrophobic polymers promote the formation of ordered porous films. Furthermore, no holes were formed in films of P0CB which is a P11CB without alkyl spacers due to its hydrophilicity. Long alkyl chains resulted in changed hydrophilic polymers to hydrophobic polymers. The introduction of long alkyl chains as a spacer between the biphenyl moiety and polymer backbone is preferred in the cases of particularly few amounts of biphenyl groups in the polymer. The biphenyl groups showed the ability to improve film formability.

Graphical abstract

KEYWORDS:

• Word
• well-defined star polymer
• breath-figure method
• porous film
• side-chain-type LC polymer

Disclosure statement

No potential conflict of interest was reported by the authors.