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New amphiphilic random copolymers containing hydrophobic dodecyl (C12) chain and hydrophilic l-glutamic acid were synthesized, and their self-assembly in solution as well as on the solid surfaces was investigated. The self-assembly behavior of these polymers are largely dependent on their hydrophilic and hydrophobic balances. The copolymer with a more hydrophobic alkyl chain (∼90%) self-assembled into giant vesicles with a diameter of several micrometers in a mixed solvent of ethanol and water. When the hydrophobic ratio decreased to ca. 76%, the polymer self-assembled into conventional vesicles with several hundred nanometers. The giant vesicles could be fused in certain conditions, while the conventional vesicles were stable. When the content of the hydrophilic part was further increased, no organized structures were formed. On the other hand, when the copolymer solutions were directly cast on solid substrates such as silicon plates, films with organized nanostructures could also be obtained, the morphology of which depended on solvent selection. When ethanol or methanol was used, spheres were obtained. When dichloromethane was used as the solvent, honeycomb-like morphologies were obtained. These results showed that through appropriate molecular design, random copolymer could self-assemble into various organized structures, which could be regulated through the hydrophobic/hydrophilic balance and the solvents. [ABSTRACT FROM AUTHOR]

We have developed a simple, efficient, and highly reproducible method to fabricate the large-area biomimetic superhydrophobic polymer surfaces having hierarchical structures of micrometer-sized irregular steps and nanometer-sized fibrils. Commercial Al plates (99.0%) were etched using Beck’s dislocation etchant (mixture of HCl and HF) for different time periods in order to alter the structure of the etched Al surfaces from micrometer-sized to highly rough nanometer-sized irregular steps. These hierarchical structures could be easily replicated onto the surface of various thermoplastic polymer plates from the etched Al templates by applying heat and pressure; many polymer replicas without any significant deviations from each other could be duplicated from the same etched Al master templates. All of thermoplastic polymer replicas having hierarchical structures exhibited superhydrophobic properties with water contact angles of larger than 150°. Especially, the surfaces of the high-density polyethylene (HDPE) replicas having nanometer-sized curled strands exhibited superhydrophobicity with a static water contact angle of ∼160° and a sliding angle of less than 2°. These superhydrophobic HDPE replicas having nanometer-sized curled strands showed excellent stability after being exposed to various organic solvents and aqueous solutions of various pH. [ABSTRACT FROM AUTHOR]