Super-hydrophobic surfaces have attracted significant attention recently

and various preparing methods have been reported

such as solgel method

plasma etching

phase separation

templatebased extrusion and so on.Besides them

the solvent evaporationphase separation was a relatively simple one

but only polymers with particular structure

such as block copolymers and polymer blends

were successfully applied by this method

Moreover

some complicate postprocedures or rigorous special environments were often essential.Herein we reported a simple way to facile a superhydrophobic surface of random copolymers just by onestep casting the polymer solution onto a solid surface.The films had many micro and nanoscale convexities and grooves with multiplex structures distributed on the surface

which appeared like a lotus leaf surface.The microscale roughness and low surface energy together endowed the films excellent superhydrophobic ability even without further modification.The water contact angle was about 155°～160°

and the sliding angle was less than 3°. The random copolymers of metharcylate (MMA) and perfluoroalkylethyl acrylate (FMA) were synthesized by microemulsion polymerization.The polymerization was carried out with sodium dodecylsulfate-C7F15COONH4-n-butanol as emulsifier

K2S2O8NaHSO3-CuSO4 redox as initiator.The emulsion was poured into excess methanol and washed by water.Then the polymer was purified several times by dissolving in acetone and precipitation by methanol.The copolymers were characterized by 1H-NMR

FTIR

GPC and fluorine element analysis.Superhydrophobic films were prepared by a onestep casting process.First

the copolymers were dissolved in F-113 to form homogeneous solutions

and then cast on 2 cm× 2 cm clean glass plates at preset temperatures in windtight environment.When the solvent was evaporated

superhydrophobic films were formed. It was found that when a good solvent of PMMA was used

such as tetrahydrofuran (THF)

acetone

etc.

or the mixed solvents of THFF113

acetoneF113 etc.

a smooth surface with water contact angles less than 130° was obtained.A superhydrophobic film could not gotten at these cases.It was regarded that the movement and interpretation of copolymer segments had dominative effects on the films morphology.The concentration of the polymer solution had great effect on the morphology of the films prepared.The casting solution concentration should be in an appropriate scale

the best concentration (c) was about 5×10-3 g/mL≤c≤c0

where c0 was the critical concentration of copolymer in F113.What was more

the temperature and pressure should also be proper.The possible reason of leading to the superhydrophobic properties of these films was due to the combination of micro and nanoscale binary roughness and low surface energy.The mechanism of forming these films based on the micelle aggregation model and was further discussed in this paper.These special films with both many convexities and grooves were formed because of the intrinsic properties of the random copolymer and a proper solution concentration as well as the forming conditions. In conclusion

using F113 as solvent

PFMAPFMA random copolymers can facile superhydrophobic surfaces by the solvent evaporationphase separation method.