TY - JOUR A1 - Koc, Julian A1 - Schardt, Lisa A1 - Nolte, Kim A1 - Beyer, Cindy A1 - Eckhard, Till A1 - Schwiderowski, Philipp A1 - Clarke, Jessica L. A1 - Finlay, John A. A1 - Clare, Anthony S. A1 - Muhler, Martin A1 - Laschewsky, André A1 - Rosenhahn, Axel T1 - Effect of dipole orientation in mixed, charge-equilibrated self-assembled monolayers on protein adsorption and marine biofouling JF - ACS applied materials & interfaces N2 - While zwitterionic interfaces are known for their excellent low-fouling properties, the underlying molecular principles are still under debate. In particular, the role of the zwitterion orientation at the interface has been discussed recently. For elucidation of the effect of this parameter, self-assembled monolayers (SAMs) on gold were prepared from stoichiometric mixtures of oppositely charged alkyl thiols bearing either a quaternary ammonium or a carboxylate moiety. The alkyl chain length of the cationic component (11-mercaptoundecyl)-N,N,N-trimethylammonium, which controls the distance of the positively charged end group from the substrate's surface, was kept constant. In contrast, the anionic component and, correspondingly, the distance of the negatively charged carboxylate groups from the surface was varied by changing the alkyl chain length in the thiol molecules from 7 (8-mercaptooctanoic acid) to 11 (12-mercaptododecanoic acid) to 15 (16-mercaptohexadecanoic acid). In this way, the charge neutrality of the coating was maintained, but the charged groups exposed at the interface to water were varied, and thus, the orientation of the dipoles in the SAMs was altered. In model biofouling studies, protein adsorption, diatom accumulation, and the settlement of zoospores were all affected by the altered charge distribution. This demonstrates the importance of the dipole orientation in mixed-charged SAMs for their inertness to nonspecific protein adsorption and the accumulation of marine organisms. Overall, biofouling was lowest when both the anionic and the cationic groups were placed at the same distance from the substrate's surface. KW - SAM KW - antifouling coatings KW - zwitterionic KW - XPS KW - Navicula perminuta KW - Ulva linza KW - SPR Y1 - 2020 U6 - https://doi.org/10.1021/acsami.0c11580 SN - 1944-8244 SN - 1944-8252 VL - 12 IS - 45 SP - 50953 EP - 50961 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Patel, Dhananjay I. A1 - Noack, Sebastian A1 - Vacogne, Charlotte D. A1 - Schlaad, Helmut A1 - Bahr, Stephan A1 - Dietrich, Paul A1 - Meyer, Michael A1 - Thissen, Andreas A1 - Linford, Matthew R. T1 - Poly(L-lactic acid), by near-ambient pressure XPS JF - Surface Science Spectra N2 - Near ambient pressure - x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., at 2500Pa or higher. With NAP-XPS, one can analyze moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission we show C 1s, O 1s, and survey NAP-XPS spectra from poly(L-lactic acid). The C 1s and O 1s envelopes were fit with three and two Gaussian-Lorentzian sum functions, respectively. Water vapor (800Pa) was used as the residual gas for charge compensation, which was confirmed by the sharp peak at 535.0 eV in the O 1s narrow scan. The uniqueness plot corresponding to the C 1s fit shows that the fit parameters had statistical significance. C 1s and O 1s spectra of PLLA damaged by exposure to x-rays for ca. 1 hour are also included. Published by the AVS. KW - near-ambient pressure X-ray photoelectron spectroscopy KW - NAP-XPS KW - XPS KW - Water Vapor Y1 - 2019 U6 - https://doi.org/10.1116/1.5110309 SN - 1055-5269 SN - 1520-8575 VL - 26 IS - 2 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Jain, Varun A1 - Wheeler, Joshua J. A1 - Ess, Daniel H. A1 - Noack, Sebastian A1 - Vacogne, Charlotte D. A1 - Schlaad, Helmut A1 - Bahr, Stephan A1 - Dietrich, Paul A1 - Meyer, Michael A1 - Thissen, Andreas A1 - Linford, Matthew R. T1 - Poly(gamma-benzyl l-glutamate), by near-ambient pressure XPS JF - Surface science spectra : SSS : an international journal & database devoted to archiving spectra from surfaces & interfaces N2 - Near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i. e., at greater than 2500 Pa. In this study, poly(.- benzyl L- glutamate) (PBLG) with a molar mass of 11.3 kg/mol was analyzed by NAP-XPS; here, we show the survey, C 1s, N 1s, and O 1s narrow scans of PBLG. The C 1s peak envelope was fitted in three different ways, to five, six, or seven synthetic peaks. In each fit, there was also a shake-up signal. The O 1s narrow scan was well fit with three peaks: CZO and CvO in a 1:2 ratio from the polymer, and a higher energy signal from water vapor. Hartree-Fock orbital energies of a model monomer served as a guide to an additional fit of the C 1s envelope. KW - near-ambient pressure x-ray photoelectron spectroscopy KW - NAP-XPS KW - XPS KW - polymer KW - poly(gamma-benzyl L-glutamate) KW - PBLG Y1 - 2019 U6 - https://doi.org/10.1116/1.5109121 SN - 1055-5269 SN - 1520-8575 VL - 26 IS - 2 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Madaan, Nitesh A1 - Romriell, Naomi A1 - Tuscano, Joshua A1 - Schlaad, Helmut A1 - Linford, Matthew R. T1 - Introduction of thiol moieties, including their thiol-ene reactions and air oxidation, onto polyelectrolyte multilayer substrates JF - Journal of colloid and interface science KW - Thiol-ene KW - Layer-by-layer KW - XPS KW - ToF-SIMS KW - Hydrophobic KW - AFM KW - Ellipsometry Y1 - 2015 U6 - https://doi.org/10.1016/j.jcis.2015.08.017 SN - 0021-9797 SN - 1095-7103 VL - 459 SP - 199 EP - 205 PB - Elsevier CY - San Diego ER -