Polydimethyl siloxane - PDMS

Further evidenee of the oceurrence of adhesion-indueed plastie flow was supplied by Vrtis et al. [109]. In this study, Vrtis removed gold and tin micrometer-size partieles from and alternating block copolymer of polyester and polydimethyl-siloxane (PDMS) by amalgamating with mereury. SFM mierographs of the sub-... 

Top plate material Polydimethyl-siloxane (PDMS) Tube for electro-osmotic flow inner diameter length 500 pm 20 mm... 

Gillmor SD, Larson BJ, Braun JM, Mason CE, Cruz-Barba LE, Denes F, La-gally MG (2002) Low-contact-angle polydimethyl siloxane (PDMS) membranes for fabricating micro-bioarrays. Proceedings of the 2nd Annual IEEE-EMBS Special Topic Conference on Microtechnologies in Medicine and Biology, Madison WI, USA, p 51... 

Such an example has been recently worked out, combining a very hard block i.e. polypivalolactone (PPVL), with a thermostable elastomer segment i.e. polydimethyl-siloxane (PDMS), using the reactions sequence described in scheme 3. (One should note that the starting PDMS has been obtained through a previously described procedure (14), avoiding any unstable Si-O-C bond in the final produc t). 

The selective dense layer of hydrophilic membranes is made from different polymers with a high affinity for water. These polymers contain ions, oxygen functions like hydroxyl, ester, ether or carboxylic moieties, or nitrogen as imino or imi-do groups. Preferred hydropilic polymers are polyvinylalcohol (PVA) [32], poly-imides, cellulose acetate (CA) or natural polymers like chitosan [33] or alginates. Organophilic membranes usually consist of crosslinked silicones, mostly polydimethyl siloxane (PDMS) or polymethyl octyl siloxane (POMS). 

Fig. 12. Relative integral permeability P/PFDMS of propane through polydimethyl siloxane (PDMS) — poly(ethylene-copropylene) rubber (EPR) blend membranes as a function of blend...

As an example, gas flow from a cola beverage was analyzed and calibration of benzalde-hyde was performed as described in Support Protocol 1. A 100-pm-thick polydimethyl-siloxane (PDMS) SPME fiber was used to extract the gas flow from the cola beverage. Since equilibrium with the flow concentration was determined to occur within 5 min for the slowest-equilibrating compound, the fiber was exposed to the gas flow for 5 min and then desorbed in the injection port of a GC/MS. A 0.01 %... 

A list of typical commercial pervaporation membranes [23] is given in Table 3.1. Commercial hydrophilic membranes are very often made of polyvinyl alcohol (PVA), with differences in the degree of crosslinking. Commercial hydrophobic membranes often have a top layer in polydimethyl siloxane (PDMS). However, a wide variety of membrane materials for pervaporation can be found in the literature, including polymethylglutamate, polyacrylonitrile, polytetrafluoroethylene, polyvinylpyrrolidone, styrene-butadiene rubber, polyacrylic acid, and many others [24]. A comprehensive overview of membrane materials for pervaporation is given by Semenova et al. [25],... 

Figure 8.5 Linear dependence of the NMR standard parameter, cc, on the modulus of elasticity E measured on randomly crosslinked polydimethyl siloxane (PDMS) chains. NMR measurements were performed without any sample deformation (redrawn from [19])...

Needle Trap Device Particularly interesting is development of the needle trap device (NTD) in an attempt at miniaturization of the sorption traps used in the analysis of gas samples. A sorbent bed positioned inside a needle (mounted in a gas-tight syringe) acts as a sorption trap. Different materials such as polydimethyl-siloxane (PDMS), carboxenes, carbopacks, Tenax, divinylbenzene (DVB), and other polymers have been employed as sorbents. 

Si NMR of siloxane systems has been used in studying organosilicone containing block copolymers to determine block length and chemical redistribution during polymerization. (85) Block copolymers of bisphenol A polycarbonate (BPAP) and polydimethyl-siloxane (PDMS) [20] were studied by both and Si NMR to determine a variety of structural parameters. 

In organophilic membranes the separation layer is typically formed from siloxanes like polydimethyl siloxane (PDMS) or polyoctylmethyl siloxane (POMS). 

Undissolved oil droplets form in the surface of the film, and this can lead to film rupture. Several examples of oils may be used alkyl phosphates, diols, fatty acid esters and silicone oils (e.g., polydimethyl siloxane PDMS). 

Determinations of semi and nonvolatile compounds have mainly focused on benzothiophene and other hetero aromatic substances. Popp et al. favored polyacrylate for the enrichment of benzothiophenes. LODs between 0.4 and 5 ng/1 were reached. Usable results were also found with the divinylbenzene/polydimethyl siloxane (PDMS) fiber recommended for compounds with a higher molecular weight. Johansen et al. applied polyacrylate with limits of detection between 20 and 40 ng/1 for thiophene and several benzothiophenes. 

It is the monomer for other polysiloxanes that are the base of most silicon oils. Also, methyl- and phenyl-substituted polyoxysilane (MPSP) and polydimethyl-siloxane (PDMS) have been used for investigation of catalyst deactivation by organo-silica compounds. Table 1 summarises studies on the deactivation of oxidation catalysts by organo-silica compounds. 

The combination of a SPME device with a pyrolysis gas chromatographic (GC) IMS system improved the limit of detection of tributylphosphate (TBP, which served as a simulant) in water by a factor of 20 compared to the same system without the SPME device. SPME fibers were also used to sample headspace vapors of several types of nerve agents, and the fibers were introduced directly into a modified ESI source for subsequent detection by IMS and mass spectrometry (MS). A SPME-IMS system, with thermal desorption, was also used to screen soil samples for precursor and degradation products of CWAs, and it was found that fibers of polydimethyl-siloxane (PDMS) were superior to PDMS-divinylbenzene fibers. ... 

In an elastomer (rubber), the macromolecules are cross-linked. The cross-linldng degree is moderate so that elastomers can be stretched easily. A transparent elastomer widely used in microfluidics is the sdicOTie rubber polydimethyl-siloxane (PDMS). 

The mold used is made of a thin polydimethyl-siloxane (PDMS) membrane attached to a rigid plate of glass as shown in Fig. 3 [4]. The plate has holes to introduce the polymer solution and to connect to vacuum. The valve to vacuum is closed while the polymer solution is applied at several inlets. The ESA process takes place on the glass surface when the capillaries are filled with the polymer solution. Finally, the vacuum is released and the mold is removed. As a result, a polymer which has the same pattern as the mold is obtained. 

Different composite membranes consisting of polyethersulfone (PES) as a sublayer and polydimethyl siloxane (PDMS) coating as a top layer have been prepared by Gudernatsch et al. (1991). By varying the polymer concentration in the casting solution of the sublayer, different properties were obtained. These membranes were used for PV. 

Kim, J. H., Lau, K. T., Shepherd, R., Wu, Y., Wallace, G. and Diamond, D. (2008). Performance characteristics of a polypyrrole modified polydimethyl-siloxane (PDMS) membrane based microfluidic pump. Sensors and Actuators A Physical 148, pp. 239-244. 

Amid et al. used a microstructured modified T-junction realized in polydimethyl-siloxane (PDMS). At the T-junction of two channels, an additional third diaimel joins the junction forming a 45° angle with the other diaimels (Figure 22.17). 

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