Honeycomb porous films of pentablock copolymer on liquid substrates via breath figure method and their hydrophobic properties with static and dynamic behaviour

Abstract

An amphiphilic pentablock copolymer of poly(trifluoroethyl methacrylate)-b-poly(methyl methacrylate)-b-poly(ethylene glycol)-b-poly(methyl methacrylate)-b-poly(trifluoroethyl methacrylate) (PTFEMA-b-PMMA-b-PEG-b-PMMA-b-PTFEMA) was proposed to fabricate honeycomb porous films on various liquid substrates through breath figure method. This work reports an investigation on the morphologies of the pores on different liquid substrates, and discusses the hydrophobic properties of the films with different surface morphologies. The morphologies of the films prepared on the silicon wafer solid substrate and the methyl silicone oil liquid substrate were compared, and it was found that the pore size was larger and the regularity was lower on the methyl silicone oil substrate. It was noteworthy that the important influencing factor for the formation of the porous structures was the surface thermodynamics. In addition, the porous structures prepared on various liquid substrates were related to the surface tensions and viscosities of the liquid solvents. The pore size was increased by enhancing the surface tension of the liquid solvent. In addition, an increase in the viscosity leads to an increase in the pore size. Finally, the hydrophobic properties including wettability and water droplet impact behaviour of porous and pincushion structured films with different surface morphologies obtained from the liquids substrates were also investigated. Moreover, the water droplets exhibited different dynamic evolutions after impact on the flat, porous and peeled surfaces.