Static secondary ion mass spectrometry (S-SIMS) allows the chemical characterization of the constituents in the upper monomolecular layer of a solid sample Within the range of micro-analytical methods, S-SIMS occupies a rather unique position in that it combines monolayer sensitivity with the capability to generate molecular information In general, elemental ions, structural fragments, molecular and adduct ions are generated from both inorganic and organic molecules, including polymers The chemical analysis of the upper monolayer makes S-SIMS especially suited to the study of the interface chemistry in a variety of materials Polymer applications take an important place because S-SIMS allows a lot of information on these often intractable materials, eg, identification, detection of surface functionalities, study of segregation of copolymer components and molecular weight (MW) distributions In addition to the qualitative identification, S-SIMS allows high reproducibility and thereby permits quantitative studies with the aid of standards Finally, S-SIMS offers imaging capabilities to visualize directly the distribution of given components within the upper surface layer of solids Mapping with high lateral resolution is feasible for elemental ions and in favorable cases also for organic compounds This review aims at a comprehensive coverage of the S-SIMS literature of the past decade It comprises two parts, of which the first part deals with the more general aspects of the technique It begins with a brief tutorial review of instrumentation, methodology and current concepts of ion formation Particular attention is given to the link and difference with the matured dynamic SIMS method Finally, imaging in S-SIMS is discussed Application of S-SIMS to complex materials makes the interpretation of signals, in terms of the sample composition, intricate but crucial Therefore, the features of inorganic and organic mass spectra are surveyed to assess the structure specificity and the kind of information obtainable



The second part of this review focuses on a variety of applications, primarily in the field of material sciences Detailed studies on the surface chemistry of catalysts are discussed The increasing importance of surface modification and tailoring to improve the interface properties has generated a wide range of applications Examples from different technologies and industrial processes, such as semiconductors, paint, composite materials and corrosion protection of metals, are highlighted Attention is devoted to the complementarity between S-SIMS and other micro-analytical surface techniques The review aims at being of interest on the one hand to the S-SIMS users looking for interesting application areas and on the other hand, to the application chemists searching a method, potentially capable of yielding specific information for their material analysis problem © 1999 John Wiley & Sons, Inc, Mass Spec Rev 18: 1–81, 1999

Static secondary ion mass spectrometry (S-SIMS) Part 1: methodology and structural interpretation

Mussel-inspired fabrication of structurally stable chitosan/polyacrylonitrile composite membrane for pervaporation dehydration

Different polydimethylsiloxane (PDMS) nanocomposite membranes were synthesized by incorporating various contents of nanosized silica particles to improve the PDMS pervaporation (PV) performance. A uniform dispersion of silica nanoparticles in the PDMS membranes was obtained. The nanocomposite membranes were characterized morphologically by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results showed that surface roughness increases by incorporating silica, and this decreases absorption of penetrants on the membrane. Swelling studies showed that the presence of silica nanoparticles into the PDMS membranes decreases degree of swelling, which can be attributed to rigidification of the PDMS matrix. Additionally, the results revealed that helium permeability decreases through the nanocomposite membranes, due to the more polymer chains packing. Effects of silica on recovery of isopropanol (IPA) from water mixtures were also investigated. Based on the results, incorporating silica nanoparticles promotes significantly the PDMS membrane selectivity because the polymer chains are rigidified and also the polymer free volume decreases. However, permeation flux decreases as diffusion of the penetrants reduces in the presence of silica nanoparticles within the PDMS membranes. As PV performance depends on operating conditions, effects of feed composition, and temperature were also studied. Moreover, recoveries of IPA, ethanol, and methanol from water mixtures were compared using the PDMS-silica nanocomposite membranes. The results demonstrated that polarity and solubility of alcohols affect permeation flux and selectivity resulting in the higher permeation flux and selectivity for IPA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Recovery of alcohols from water using polydimethylsiloxane–silica nanocomposite membranes: Characterization and pervaporation performance

Poly(dimethylsiloxane) (PDMS) copolymers containing propanethiol side chain “stickers” for forming self-assembled films on gold surfaces have been studied by various experimental techniques including ellipsometry, contact angle measurements, FT-IR, angle-dependent XPS, and ToF−SIMS. The results show that the thiol-containing side chains do not all chemisorb to the gold surfaces. In addition, the concentration of these sticker units was found to have a dominant effect on the polymer film thickness, the surface wetting properties, and the orientation of the PDMS backbone. Ab initio calculations reveal that the IR-active PDMS Si−O stretching bands can be used as indications of chain orientation, and a comparison of the calculated spectra with grazing incidence reflection IR data shows that the self-assembled PDMS backbone is predominantly aligned parallel to the surface, plausibly as a result of the chemisorption.

Formation and characterization of self-assembled films of thiol-derivatized poly(dimethylsiloxane) on gold

Studies on the coating layer in a PTFPMS/PEI composite membrane for gaseous separation

In this work we have compared and contrasted the pervaporation behaviour (separation factor and flux) of fluorosilicone dense membranes based on poly(trifluoropropylmethylsiloxane) (PTFPMS) with poly(dimethylsiloxane) (PDMS) dense membranes. In particular, pervaporation experiments were carried out at 298 K using lab-made PTFPMS, lab-made PDMS and commercial PDMS membranes in order to remove three different organic liquids pyridine (PY), isopropanol (IPA) and methylethylketone (MEK) from dilute (<10 wt.%) binary aqueous mixtures. All of the silicone membranes studied were found to be successful for the desired separations. The permeation flux of pyridine–water liquid mixtures for the PTFPMS membranes was found to increase with the pyridine concentration in the feed mixtures. The separation factor for PDMS membranes for the removal of pyridine, IPA and MEK from aqueous binary mixtures (1 wt.%) was found to be higher than that of PTFPMS membranes while the normalized flux was higher for PTFPMS membranes under identical test conditions. The effect of crosslink density of the PTFPMS membranes on the separation of pyridine–water mixtures was also studied. For a 1 wt.% feed solution the total flux increased with the molar mass between crosslinks, whereas the separation factor for pyridine–water was highest for a molar mass between crosslinks of 15,320 g mol−1.

Pervaporation of Organic Liquids from Binary Aqueous Mixtures using Poly(trifluoropropylmethylsiloxane) and Poly(dimethylsiloxane) Dense Membranes

Mass spectrometry (MS) has previously proved to be very valuable for characterizing the thermal decomposition of poly-(dimethylsiloxane) (PDMS) via pyrolysis-MS. Secondary ion mass spectrometry (SIMS) has also been applied to identify the various fragments characteristic of PDMS and thus give fingerprint'' spectra for identification purposes. This paper describes the characterization of deuterated linear PDMS -[(CD[sub 3])[sub 2]SiO][sub n]- using time-of-flight secondary ion mass spectrometry. The work is part of a program investigating the conformations and interactions of deuterated siloxanes in isotopic blends -[(CD[sub 3])[sub 2]SiO][sub n]-/-[CH[sub 3][sub 2]SiO][sub n]- using small-angle neutron scattering. It is therefore clearly important to demonstrate that no deuterium/hydrogen exchanges occurred during the synthetic methodology used.

Time-of-Flight Secondary Ion Mass Spectrometry of Deuterated Linear Poly(dimethylsiloxane)

Pervaporation of isopropanol-water mixtures using hydrophobic poly(methylphenylsiloxane) and poly(dimethylsiloxane) and hydrophilic cellulose acetate membranes

Pervaporation experiments were conducted to remove low concentration (<10wt.%) organic liquids: pyridine, isopropanol (IPA) and methylethylketone (MEK) respectively from binary aqueous mixtures using lab-made poly(methylphenylsiloxane) (PMPS) and poly(dimethylsiloxane) (PDMS) membranes. The performance of these membranes (selectivity and flux) were studied and compared with commercial PDMS membranes. The PMPS membranes showed greater selectivity towards pyridine while the PDMS membranes showed higher permeation flux and selectivity towards IPA and MEK.

A comparison of poly(methylphenylsiloxane) and poly(dimethylsiloxane) membranes for the removal of low molecular weight organic compounds from water by pervaporation

Xiao Kang Zhang

Papers

Pervaporation of Organic Liquids from Binary Aqueous Mixtures using Poly(trifluoropropylmethylsiloxane) and Poly(dimethylsiloxane) Dense Membranes

Time-of-Flight Secondary Ion Mass Spectrometry of Deuterated Linear Poly(dimethylsiloxane)

Pervaporation of isopropanol-water mixtures using hydrophobic poly(methylphenylsiloxane) and poly(dimethylsiloxane) and hydrophilic cellulose acetate membranes

A comparison of poly(methylphenylsiloxane) and poly(dimethylsiloxane) membranes for the removal of low molecular weight organic compounds from water by pervaporation