Surface Functionalization of Oxide-Covered Zinc and Iron with Phosphonated Phenylethynyl Phenothiazine

Abstract

Phenothiazines are redox-active, fluorescent molecules with potential applications in molecular electronics. Phosphonated phenylethynyl phenothiazine can be easily obtained in a four-step synthesis, yielding a molecule with a headgroup permitting surface linkage. Upon modifying hydroxylated polycrystalline zinc and iron, both covered with their respective native oxides, ultrathin organic layers were formed and investigated by use of infrared (IR) reflection spectroscopy, X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), contact angle measurement, and ellipsometry. While stable monolayers with upright oriented organic molecules were formed on oxide-covered iron, multilayer formation is observed on oxide-covered zinc. ToF-SIMS measurements reveal a bridging bidentate bonding state of the organic compound on oxide-covered iron, whereas monodentate complexes were observed on oxide-covered zinc. Both organically modified and unmodified surfaces exhibit reactive wetting, but organic modification makes the surfaces initially more hydrophobic. Cyclic voltammetry (CV) indicates redox activity of the multilayers formed on oxide-covered zinc. On the other hand, the monolayers on oxide-covered iron desorb after electrochemical modifications in the state of the oxide, but are stable at open circuit conditions. Exploiting an electronic coupling of phenothiazines to oxides may thus assist in corrosion protection.

Comparison of cathodic delamination of poly(n‐alkyl methacrylates) on iron

“…It was found than the hydrophobicity of the surface is strongly affected by the alkyl chain length in a proportional manner; as shown in the Figure . In detail, the contact angle θ of pristine iron was determined as (52 ± 3)° being in good agreement with the values reported in other works . When the substrate is covered with PMMA, the wettability is reduced, and θ shifts to higher values, namely (85 ± 4)°.…”

“…In detail, the contact angle θ of pristine iron was determined as (52 ± 3)°being in good agreement with the values reported in other works. [29] When the substrate is covered with PMMA, the wettability is reduced, and θ shifts to higher values, namely (85 ± 4)°. Even higher are the contact angles of samples coated with PBMA and PSMA, which are (110 ± 5)°and (150 ± 4)°, respectively.…”

Phosphonic acid functionalization of nanostructured Ni–W coatings on steel

“…[15,20] The P-O-metal bond can vary from ionic to covalent as a function of the identity and oxidation state of the metal ion. They have been studied on oxidized metallic surfaces and alloys such as Al [21][22][23][24][25][26], Hf [27], Nb [21,28], Ti [29][30][31][32][33][34], In [35], In-Zn [36], Zr [37,38], Ta [39], Mg [40,41], Ti-Nb [42], Ni [43], Ni-Ti [44,45], Cu [46], Ni-Cu [47], Co-Cr alloys [48], Zn [49], Fe [49] and stainless steel [50][51][52][53][54]; and also on Si [55,56] , iron oxide nanoparticles [57] and ITO films [58].…”

Delamination Kinetics of Thin Film Poly(acrylate) Model Coatings Prepared by Surface Initiated Atom Transfer Radical Polymerization on Iron

“…The surface coverage of initiators on the modified iron samples was determined as in a previous work. 26 Surface coverage (X ) of CTCS and BMPPTS was determined from comparing the peak intensities of Si 2p and N 1s peaks, respectively, to the Fe 2p peak of the substrate as [27][28][29] (…”