The influence of casting parameters on the surface morphology of PS-b-P4VP honeycomb films

The “breath figures” method provides an efficient and cost-effective method to produce highly ordered honeycomb patterns in polymeric films at micrometer and sub-micrometer dimensions. The size and regularity of the pores can be adjusted through a series of physical and chemical parameters. In this study, amphiphilic diblock copolymers, polystyrene-block-poly(4-vinyl pyridine) (PS-b-P4VP) with different lengths of P4VP, were synthesized through Reversible Addition-Fragmentation Chain Transfer polymerization. The honeycomb-patterned films were prepared from these well-defined polymers through the dynamic breath figures method. A series of physical parameters including solution concentration, flow rate, humidity of the flow, and the humidity of the casting environment, were delicately adjusted to systematically investigate their effects on the morphology of the films. These studies identified four key factors which were found to influence the formation of the pattern. No obvious effect was found on the pore size by changing the length of P4VP block. The result provides clear direction on the fabrication of PS-b-P4VP honeycomb-patterned films and more broadly contributes a deeper understanding of the processes involved in the formation of honeycomb patterns