Octadecylacrylate

A new type of mixed-mode stationary phase which incorporates both strong anion-exchange (triehtylammonium methylstyrene) moieties and C18 (octadecylacrylate) ligands was used by Scherer et al. to separate acetylsalicylic acid and three of its metabolites in less than 2 min [42], A rapid reversed EOF (1.8 mm/s) was generated over a wide range of pH, from 3 to 9. It was found that EOF velocity shows variation with pH, the magnitude of which is a function of the content of SAX versus C18 moieties. 

Column 250 X 4.1 6 (xm PolyEncap ODS (n-octadecylacrylate copol3Tnerized with vinyl silica in heptane, carrier Ultrasep ES 100 preparation described in paper)... 

Nitrophenyl-diazenyl) phenyl-l,3-diamine, 467 N-(4-Nitrophenyl)-l-prolinol, 46 Octadecylacrylate, 537... 

The polymerization of o,o-dlacetylenediphenyl glutarate and 5,7-dodecadiinediol-l,12 bis-phenylurethane. (b) The cyclization reaction of N-(para-chlorophenyl) phthalanilic acid to N-(para-chlorophenyl) phthalimidle with the elimination of water. (c) The polymerization of crystalline methacrylic acid. Finally a discussion will be undertaken of the polymerization of molecular multilayers of a number of monomers, such as vinyl stearates and a-octadecylacrylic acid, which may not fit conveniently into any of the above categories. 

PMMA = polymethyl methacrylate, PVC = poly(vinyl cinnamate) PODA = poly (octadecylacrylate) tAuAc = dimethyl-Au-trifluoro acetylacetonate... 

Figure 3. DSC thermograms of poly (octadecylacrylate) grafted silica prepared by both grafting to and grafting from methods.

Figure 4. Variation of ordered to disordered conformation of alkyl chain with temperature for poly(octadecylacrylate) grafted silica.

In addition, highly-ordered poly(octadecylacrylate) grafted silica particles prepared in both methods performed eomplete separation for mixtures of various isomeric PAHs polycyclic aromatic hydrocarbons in a methanol-water as a mobile phase as mentioned in many of our previous investigation [59]. Their elution orders are the same as those that can be observed with ODS. It is also showed that the retention factor k) increases with an increase in mobile phase polarity. The performance of Sil-to-ODA and Sil-from-ODA is imique because of its attractive temperature dependencies behavior. As shown in Fig. 7, both Sil-to-... 

Figure 10. Schematic illustration of the separation mechanism for PAHs on poly(octadecylacrylate) grafted silica.

Unusual Multilayers In previous work we demonstrated that multilayers of poly(vinyl stearate) which normally occur as X layers (head to tail) can be prepare gWith the side chains packed in Y layers (head-head-tail-tail)L By the technique described in the experimental section we have obtained an X structure for multilayers of the polymerized cadmium salt of octadecylacrylic acid, a g material that normally forms Y structures. As with vinyl stearate the turn around of the cadmium salt of octadecylacrylic acrylic acid monomer layers during the up trip through the gas-water interface is precluded by polymerizing each layer underneath the watergSurface. This has been verified by changes in the infrared spectrum and by x-ray diffraction measurements, which show that the repeat corresponds to 2SA not 56A as would be expected for head-head-tail-tall layers. 

Table II lists the basic small angle X-ray spaclngs for pure octadecylacrylic acid (ODA acid) and pure octadecylacrylamide (ODA amide) monomer and polymer multilayers and Table III gives the same information for alternating and mixed layers of these two materials.

The surfaces of liposomes have been coated [17] with thermosensitive pol5uners such as poly(A -isopropylacrylamide) [poly(NIPAM)] by taking advantage of the phase transition of polymers. The molecular structure of a hydrophobically modified poly(NIPAM), which has been studied in the preparation of temperature-sensitive Uposomes [17], is depicted in Fig. 7. Poly(NlPAM) exhibits a low critical solution temperature (LCST) around 32°C, and the LCST can be altered toward the body temperature by co-pol5unerization [56], The pol5uner is in an expanded form at low temperature, but above the critical temperature it is in a contracted form. The interactions of SUVs and hydrophobically modified poly(NIPAM) were studied by fluorescence spectroscopy [88]. More recently, sonicated DPPC and egg PC Uposomes coated with a copolymer of NIPAM and octadecylacrylate in a molar ratio of 100 1 were prepared [17,89], It was shown that above the LCST of the copolymer, the release of calcein and carboxyfluorescein from... 

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