Polyelectrolytes as new matrices for secondary ion mass spectrometry

Abstract

Significant enhancements in ion yields in time-of-flight secondary ion mass spectrometry (TOF-SIMS) are observed when water-soluble analytes are mixed with a polyelectrolyte, e.g., poly(diallyldimethylammonium chloride) or poly(sodium 4-styrenesulfonate), and then deposited in the layer-by-layer method on a surface. This previously unobserved effect is demonstrated for 5-chloro-8-methoxyquinoline appended diaza-18-crown-6, 5-(2-aminoethoxy)methyl-5-chloro-8-methoxyquinoline appended diaza-18-crown-6, acridine, 9-anthracenecarboxylic acid, and ferrocenecarboxylic acid. By optical ellipsometry film thicknesses range from ca. 5-20 Å. X-ray photoelectron spectroscopy shows significantly less analyte in the polyelectrolyte-analyte films than in the neat analytes. However, TOF-SIMS generally shows significant enhancements in ion yields from the polyelectrolyte films compared with either the neat compounds or the compounds solubilized with acid or base and then dried on a surface. These significant enhancements in ion yields also appear to extend to analyte fragments and cationized molecular species. Some enhancement is also observed for dried droplets of analytes mixed with a polyelectrolyte on surfaces. (J Am Soc Mass Spectrom 2005, 16, 1575-1582

Nanoscale Departures: Excess Lipid Leaving the Surface during Supported Lipid Bilayer Formation

“…Possibly, the significant roughness of our TiO 2 -coated substrates contributes to this observation: the rms roughness of our surfaces was ∼0.6 nm (Figure S2 in the Supporting Information). For comparison, the roughness of native oxide on silicon wafers ranges between 0.05 and 0.1 nm. − Our own measurements yield a value of ∼0.06 nm for the roughness of the native oxide layer on the silicon wafers.…”

Introduction of thiol moieties, including their thiol–ene reactions and air oxidation, onto polyelectrolyte multilayer substrates

“…Surface modification continues to be a very active area of research in modern science because of the many potential applications of functionalized surfaces in biosensors, fuel cells, photovoltaics, bioconjugate chemistry, molecular electronics, adhesion, microfluidics, etc. 1 Some of the basic building blocks of such advanced materials are self-assembled monolayers on gold, [2][3] organosilane monolayers on hydroxylated surfaces, [4][5][6][7][8] alkene and alkyne monolayers on hydrogen-terminated, nanoparticulate, and scribed silicon, [9][10][11][12][13][14][15] phosphonates on alumina, zirconia, and related substrates, [16][17][18][19][20] the many reactions of bioconjugate chemistry, 21 the layer-by-layer assembly of polyelectrolytes and other charged species, [22][23][24][25] thiol-ene chemistry, [26][27][28][29][30] and carbon nanotubes. [31][32][33] Complex molecular assemblies on surfaces may be prepared using combinations of different chemistries that are compatible with a specific substrate and each other.…”

Polyallylamine as an Adhesion Promoter for SU-8 Photoresist

“…There are similar reports in the literature of the spontaneous adsorption of other amine-containing polymers to oxide surfaces, including polyethyleneimine and polylysine (Golander & Eriksson, 1987). These types of initial layers are often employed as the starting point for polyelectrolyte multilayers (Losche et al, 1998; Sukhorukov et al, 1998; Owen et al, 2004; Lua et al, 2005).

Figure 2 Structure of the water-soluble adhesion promoter polyallylamine.

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