Reported
are the formation of rough particulate films from cross-linked diblock
copolymer vesicles and nanotubes and the wetting properties of the
resultant films. The diblock copolymers used were F66M200 and F95A135, where the subscripts
denote the repeat unit numbers, whereas M, A, and F denote poly(2-cinnamoyloxyethyl
methacrylate), poly(2-cinnamoyloxyethyl acrylate), and poly(2,2,2-trifluoroethyl
methacrylate), respectively. The precursory polymers to F66M200 and F95A135 were prepared by
atom transfer radical polymerization. In 2,2,2-trifluoroethyl methacrylate
(FEMA), a selective solvent for F, vesicles and tubular micelles were
prepared from F66M200 and F95A135, respectively. Photo-cross-linking the M and A blocks of
these aggregates yielded hollow nanospheres and nanotubes bearing
F coronal chains. These particles were dispersed into CH2Cl2/methanol, where CH2Cl2 was a
good solvent for both blocks and methanol was a poor solvent for F.
Casting CH2Cl2/methanol dispersions of these
particles yielded films consisting of hierarchically assembled diblock
copolymer nanoparticles. For example, the hollow nanospheres fused
into microspheres bearing nanobumps after being cast from CH2Cl2/methanol at methanol volume fractions of 30 and 50%.
The roughness of these films increased as the methanol volume fraction
increased. The films that were cast at high methanol contents were
superhydrophobic, possessing water contact angles of ∼160°
and water sliding angles of ∼3°.