Synthesis and Characterization of New Adhesion Promoter for Grafting Conducting Polymer on Oxide Substrate

For grafting polypyrrole layers on oxidic substrates, the synthesis and characterization of a new adhesion promoter 11‐(pyrrol‐3‐yl) undecyl trimethoxysilane (PyTMS) were described in this article. The oxidation potential of PyTMS was determined by cyclic voltammetry. The grafting behavior of such an adhesion promoter on oxidized surface and chemical deposition of polypyrrole over the modified oxidized surface were studied. The adsorbed layer on the oxidized substrates thus formed was determined by both contact angle measurements and X‐ray photoelectron spectroscopy. Chemical polymerization of terminal pyrrole moieties on such substrates yielded adhesive polypyrrole films, and SEM image showed that the morphology of the polypyrrole films was influenced by the experimental conditions.     

Hybrid nanoparticle design based on cationized gelatin and the polyanions dextran sulfate and chondroitin sulfate for ocular gene therapy

We describe the development of hybrid nanoparticles composed of cationized gelatin and the polyanions CS and DS for gene therapy in the ocular surface. The physicochemical properties of the nanoparticles that impact their bioperformance, such as average size and zeta potential, can be conveniently modulated by changing the ratio of polymers and the crosslinker. These systems associate plasmid DNA and are able to protect it from DNase I degradation. We corroborate that the introduction of CS or DS in the formulation decreases the in vitro toxicity of the nanoparticles to human corneal cells without compromising the transfection efficiency. These nanoparticles are potential candidates for the development of safer and more effective nanomedicines for ocular therapy.     

One-dimensional SAMs of (12-pyrrol-1-yl-dodecyl)-phosphonic acid templated by polyelectrolyte molecules

We present a novel method for the fabrication of one-dimensional (1-D) self-assembled monolayers and multilayers (SAMs) of (12-pyrrol-1-yl-dodecyl)-phosphonic acid (Py-DPA) on various polar surfaces using polyelectrolyte nanostructures as positive templates. Particularly, we demonstrate that (i) patterns of aligned 1-D polycation structures on a poly(dimethylsiloxane) stamp can be prepared by moving a droplet of polycation solution along the surface; (ii) these patterns can be used as templates for the ordered assembly of Py-DPA in water where Py-DPA carries a charge opposite to the charge of the template; and (iii) Py-DPA SAMs can then be transferred onto mica or silicon wafers by a printing process. These nanostructures with a polymerizable pyrrole headgroup might be useful for the creation of electrically conductive patterns of conjugated polymers.     

Pyrrole-substituted alkyl silanes as new adhesion promoters on oxidic substrates

ω-(Pyrrol-1-yl alkyl) dimethylchlorosilanes with different chain length were synthesized and characterized with IR, NMR and elemental analysis. The growth of self-assembled monolayers of ω-(pyrrol-1-yl alkyl) dimethylchlorosilanes on oxide surfaces has been investigated. The order gradually improved with adsorption time and highly ordered SAMs were obtained for nearly 2 days adsorption time. Characterization of the films has been performed with contact angle measurements, ellipsometry, SPR and grazing incident FTIR. The chemical deposition of polypyrrole on the modified surface was investigated. The thickness of polypyrrole layer was influenced by the concentration of monomer, the deposition time, and the ratio of monomer to oxidant.     

Ultra-thin layers of phosphorylated cellulose derivatives on metal surfaces

Cellulose as natural and non-toxic material is very interesting for biological applications. Its poor solubility in organic solvents can be improved by introduction of long alkyl chains. Phosphate-substituted cellulose derivatives form ultra-thin layers on several metal surfaces [1, 2]. The layers were applied on the surfaces via dip coating from dilute solutions and characterised by contact angle measurements. Initial corrosion tests were performed. These polymers were applied as adhesion promoters for steel-, titanium- and hydroxy apatite surfaces. Medical implants were pre-treated by UV irradiation, coated with the cellulose derivatives and activated by hot water treatment. The adhesion of the implants surpassed that of conventionally used PMMA systems.     

聚吡咯薄膜的电特性

含有不同的链长的w-吡咯烷基二甲基氯硅烷作为粘合剂通过自组装（SAMs）吸附于二氧化硅表面,然后聚吡咯膜化学沉积于该粘合剂修饰的表面。化学沉积的聚吡咯膜的表面形貌用扫描电镜（SEM）及原子力显微镜（AFM）表征。除短链外不同链长的粘合剂对聚吡咯膜的厚度影响不大。聚吡咯膜的电特性用电流-电压表征。结果显示电流与粘合剂的链长无关。电特性表明载流子迁移率为1.4 ´ 10-4 cm2×V-1.s –1。     

Infrared Spectra of Alkylphosphonic Acid Bound to Aluminium Surfaces

Summary: The infrared absorption (IR) spectrum of alkyl phosphonic acid adsorbed on the α-Al₂O₃ (0001) surface has been calculated by means of a density-functional based tight-binding method. Thereby mono-dentate, bi-dentate and tri-dentate bonding of the acid to the surface have been considered. In addition, experimentally obtained Fourier Transform Infrared Spectra (FTIR) of octadecylphosphonic acid (ODPA) on the natural surface of aluminium have been included. The absence of the PO band in the experimental surface spectrum and in the calculated spectrum of the tridentate adsorption complexes showed that adsorption of (alkyl)phosphonic acids on aluminium favours tridentate bonding, where the acid is bound to the surface via three symmetric P O Al bonds.