Supramolecular PS-P4VP diblock copolymer thin films slowly dip-coated from chloroform solutions

This contribution shows the strong influence of using chloroform instead of THF on the characteristics of thin films of supramolecular block copolymers of poly(styrene-b-4-vinyl pyridine) dip-coated in the so-called “capillarity” regime from solutions containing 1-naphthol or 1-naphthoic acid. The small molecule content in the dip-coated films was investigated by infrared spectroscopy and the film morphology by atomic force microscopy. It was found that the small molecule content in the films is constant with dip-coating rate in the range investigated, but it is higher for 1-naphthoic acid than for 1-naphthol. The main morphology observed was in the form of “islands” and “holes”, which is typical of flat-on lamellae. These findings are related to hydrogen-bonding between the small molecule and pyridine being conserved in chloroform and to the good solubility of both blocks in this solvent, with differences between the two small molecules related to their differing H-bond strengths. These findings contrast strongly with what was observed previously using THF as a solvent, for which the SM content increases with dip-coating rate and the morphologies are mainly spherical and cylindrical in the same parameter range.