Ali Dirani

Publications (14) View all

• Article: Reversible Photomodulation of the Swelling of Poly(oligo(ethylene glycol) methacrylate) Thermoresponsive Polymer Brushes

  Ali Dirani, Xavier Laloyaux, Antony E. Fernandes, Bertrand Mathy, Olivier Schicke, Olivier Riant, Bernard Nysten, and Alain M. Jonas
  Macromolecules 11/2012; · 5.17 Impact Factor
• Article: Thicker is Better? Synthesis and Evaluation of Well-Defined Polymer Brushes with Controllable Catalytic Loadings.

  Antony E Fernandes, Ali Dirani, Cécile d'Haese, Gladys Deumer, Weiming Guo, Peter Hensenne, Fady Nahra, Xavier Laloyaux, Vincent Haufroid, Bernard Nysten, Olivier Riant, Alain M Jonas
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  ABSTRACT: Polymer brushes (PBs) have been used as supports for the immobilization of palladium complexes on silicon surfaces. The polymers were grown by surface-initiated atom-transfer radical polymerization (SI-ATRP) and postdecorated with dipyridylamine (dpa) ligands. The pendant dpa units were in turn complexed with [Pd(OAc)(2) ] to afford hybrid catalytic surfaces. A series of catalytic samples of various thicknesses (ca. 20-160 nm) and associated palladium loadings (ca. 10-45 nmol cm(-2) ) were obtained by adjusting the SI-ATRP reaction time and characterized by ellipsometry, X-ray reflectivity, X-ray photoelectron spectroscopy, and inductively coupled plasma mass spectrometry (ICP-MS). ICP-MS revealed a near-linear relationship between thickness of the polymer brush and palladium content, which confirmed the robustness of the preparation and postmodification sequence presented herein, rendering possible the creation of functional architectures with predefined catalytic potential. The activities of the catalytic PBs were determined by systematically exploring a full range of substrate-to-catalyst ratios in a model palladium(0)-catalyzed reaction. Quantitative transformations were observed for loadings down to 0.03 mol % and a maximum turnover number (TON) of around 3500 was established for the system. Comparison of the catalytic performances evidenced a singular influence of the thickness on conversions and TONs. The limited recyclability of the hairy catalysts has been attributed to palladium leaching.
  Chemistry 10/2012; · 5.93 Impact Factor
• Article: Chemically amplified photoresists for 193‐nm photolithography: Effect of molecular structure and photonic parameters on photopatterning

  Hassan Ridaoui, Ali Dirani, Olivier Soppera, Esma Ismailova, Cyril Brochon, Guy Schlatter, Georges Hadziioannou, Raluca Tiron, Philippe Bandelier, Claire Sourd
  Journal of Polymer Science Part A Polymer Chemistry 02/2010; 48(6):1271 - 1277. · 3.92 Impact Factor
• Article: Opposite responses of cells and bacteria to micro/nanopatterned surfaces prepared by pulsed plasma polymerization and UV-irradiation.

  L Ploux, K Anselme, A Dirani, A Ponche, O Soppera, V Roucoules
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  ABSTRACT: Chemically and topographically patterned surfaces have high potential as model surfaces for studying cell and bacteria responses to surface chemistry and surface topography at a nanoscale level. In this work, we demonstrated the possibility to combine pulsed plasma polymerization and UV-irradiation to obtain topographical patterns and chemical patterns perfectly controlled at microlateral resolution and sub-micrometer depth level. Biological experiments were conducted using human osteoprogenitor cells and Escherichia coli K12. Proliferation and orientation of cells and bacteria were analyzed and discussed according to the size and the chemistry of the features. This work showed interesting opposite behavior of bacteria compared to eukaryotic cells, in response to the surface chemistry and to the surface topography. This result may be particularly useful on medical implants. From a methodological point of view, it highlighted the importance of working with versatile and well-characterized surfaces before and after sterilization. It also points out the relevance and the necessity of analyzing eukaryotic cell and bacteria adhesion in parallel way.
  Langmuir 07/2009; 25(14):8161-9. · 4.19 Impact Factor
• Source

  Available from: InTech

  Chapter: DUV Interferometry for Micro and Nanopatterned Surfaces

  Olivier Soppera, Ali Dirani, Fabrice Stehlin, Hassan Ridaoui, Arnaud Spangenberg, Fernand Wieder, Vincent Roucoules
  12/2011; , ISBN: 978-953-307-602-7