A novel strategy is reported to produce low surface energy poly(pentadecafluorooctyl-5-norbornene-2-carboxylate) brushes (PNCA-F 15 ) on surfaces of variable metals and metallic oxides. PNCA-F 15 brushes are grafted from biomimic catecholic initiator via surface-initiated ring-opening metathesis polymerization at ambient conditions. The biomimic catecholic initiator can assemble on a variety of substrates, such as Ti(TiO 2 ), Al(Al 2 O 3 ), steel, Au, Cu, Ag, and Zn, and on both nanoparticles and planar substrates, allowing successful grafting of low surface energy polymer brushes from these substrates. The polymer brush modified substances were characterized by thermogravimetric analysis, X-ray photoelectron spectroscopy, water contact angle measurements, and atomic force microscopy. The PNCA-F 15 brushes grow progressly with time with highly uniform surface coverage. Very uniform polymer layer with the thickness 11 nm is obtained after 2 h polymerization at 0.25 M monomer concentration. Thermogravimetric analysis shows the grafting amount of PNCA-F 15 is 39.3% (2 h). Upon grafting on rough surfaces, e.g., electrochemically anodized alumina and titania, superhydrophobicity and superoleophobicity in particular can be achieved; e.g., the PNCA-F 15 grafted rough TiO 2 nanotubes films exhibit static water contact angle of 170°.
In this paper, a novel strategy was reported to produce ternary nanocomposite containing TiO 2 nanowires, poly [(dimethylamino)ethyl methacrylate] (PDMAEMA) brush and Pd nanoparticles. PDMAEMA brushes were grafted from catecholic initiator anchored on TiO 2 nanowires via surface-initiated atom transfer radical polymerization (SI-ATRP) at ambient conditions. The PDMAEMA uniformly covered the surface of TiO 2 nanowires and the two component of PDMAEMA and TiO 2 shows clear boundary interface. PDMAEMA brushes were derived with CH 3 I to form quaternized-PDMAEMA (Q-PDMAEMA) so as to facilitate anion exchange with PdCl 4 2-, which was followed by in situ reduction with NaBH 4 to obtain the TiO 2 nanowires-Q-PDMAEMA/Pd(0) ternary nanocomposite. Pd nanoparticles have very small size of about 2-4nm and monodisperse, uniformly distributed among polymer brush network. Interestingly, after reduction reaction, concurrent with generation of Pd nanoparticles, the ammonium cations were largely recovered, which allows further breath-in PdCl 4 2counterions and uploads more Pd nanopaticles by repeated steps. The responsivity of both PDMAEMA and Q-PDMAEMA decorated TiO 2 nanowires was studied in response to pH and salt solution. The electrocatalytic behavior of the ternary nanocomposite was investigated.
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