Clean Surfaces: Their Preparation and Characterization for Interfacial Studies
About: This article is published in Journal of The Electrochemical Society.The article was published on 1970-11-01. It has received 155 citations till now.
Citations
More filters
TL;DR: In this paper, a review of equilibrium and dynamic aspects of surface tension and adsorption, primarily of single nonmicellar or premiceller surfactants at the air/water interface, is presented.
675 citations
TL;DR: In this article, a qualitative evaluation of eight chemical methods commonly used to clean glass microscope slides in preparation for silanization was presented, and the mean contact angle of deionized water was measured before covalent attachment of (3-mercaptopropyl)triethoxysilane to assess the efficacy of each procedure.
367 citations
01 Oct 1976
TL;DR: In this article, it is suggested that ionization of silica reduces its affinity for nonionic compounds by a general "salting-out" effect, since any factor which favors the presence of water on the surface (in preference to organic compounds) tends to weaken the attachment of the solute.
Abstract: Adsorption of poly(ethylene oxide) (PEO) of high molecular weight from water on to various forms of silica has been investigated and correlated with the varying degrees of flocculation produced. Both effects are most marked with silicas which carry “isolated” silanol groups and hydrophobic groups (either methyl or siloxane). A combination of hydrogen bonding and hydrophobic association may be responsible. Silicas which have been fully dehydroxylated by heating above 1000°C do not adsorb PEO and are extremely slow to rehydrate in water. The marked influence of pH on the adsorption of this nonionic polymer (and of others such as polyvinyl alcohol and polyacrylamide) needs explanation. It is suggested that ionization of silica reduces its affinity for nonionic compounds by a general “salting-out” effect, since any factor which favors the presence of water on the surface (in preference to organic compounds) tends to weaken the, already fragile, attachment of the solute. The concept of competition between water and ether units for surface sites provides a unified qualitative explanation of all the phenomena reported.
291 citations
TL;DR: In this article, the ionic strength of the aqueous phase was found to play an important part in determining particle size; this was explained in terms of a limited coagulation process occurring at the stage involving the nucleation of polymer particles.
Abstract: Methods have been devised for the formation of monodisperse polystyrene latices in the absence of added surface active agents. The particles are stabilised, as a colloidal dispersion, by surface groupings which are an integral part of the particle and are not removed by dialysis. By suitable variation of the ionic strength of the aqueous phase, the initiator concentration and the polymerisation temperature, the final particle size obtained in single-stage reactions was varied between c. 0.15 and 1.0 μm. The coefficient of variation on particle diameters was usually less than 5%. The ionic strength of the aqueous phase was found to play an important part in determining particle size; this was explained in terms of a limited coagulation process occurring at the stage involving the nucleation of polymer particles. Conductometric titration experiments revealed the presence of sulphate, carboxyl and hydroxyl groups on the particle surfaces. Molecular weight determination of the polystyrene formed showed that this was lower than that formed in conventional emulsion polymerisation.
248 citations
TL;DR: Self-assembled purines and pyrimidines are used on planar gold surfaces and on gold-coated atomic force microscope (AFM) tips to directly probe intermolecular hydrogen bonds and forces as low as two interacting base pairs have been measured.
Abstract: We have used self-assembled purines and pyrimidines on planar gold surfaces and on gold-coated atomic force microscope (AFM) tips to directly probe intermolecular hydrogen bonds. Electron spectroscopy for chemical analysis (ESCA) and thermal programmed desorption (TPD) measurements of the molecular layers suggested monolayer coverage and a desorption energy of about 25 kcal/mol. Experiments were performed under water, with all four DNA bases immobilized on AFM tips and flat surfaces. Directional hydrogen-bonding interaction between the tip molecules and the surface molecules could be measured only when opposite base-pair coatings were used. The directional interactions were inhibited by excess nucleotide base in solution. Nondirectional van der Waals forces were present in all other cases. Forces as low as two interacting base pairs have been measured. With coated AFM tips, surface chemistry-sensitive recognition atomic force microscopy can be performed.
207 citations