PVC matrices

The preparation of an ion-selective electrode for salicylate is described. The electrode incorporates an ion-pair of crystal violet and salicylate in a PVC matrix as the ion-selective membrane. Its use for the determination of acetylsalicylic acid in aspirin tablets is described. A similar experiment is described by Creager, S. E. Lawrence, K. D. Tibbets, C. R. in An Easily Constructed Salicylate-Ion-Selective Electrode for Use in the Instructional Laboratory, /. Chem. Educ. 1995, 72, 274-276. 

The results of Jamieson and McNeill cannot be accounted for by the intramolecular mechanism proposed by Grassie and coworkers [136,137] for the thermal degradation behavior of VC/VAc copolymers (Eqs, [28] and [29]). They can be accounted for much more convincingly by the alternative approach proposed by Naqvi based on polar interactions within the PVC matrix. Just like in copolymers even in blends, the polar carbonyl group of PVAc intensifies the concentration of like-poles in the PVC matrix resulting in destabilization. 

PBR increases the inherent stability of PVC by acting as a nonpolar dispersant and reducing the undesirable polar tensions within the PVC matrix. 

Table 14. Thermal effect (dH) of interaction of chalk coated with different polymeric materials with the PVC matrix and the mechanical properties of compositions with 40% by mass of chalk [210]...

The Vinyloop process was developed by Solvay as a response to a challenge from one of its customers, Ferrari Textiles Techniques (France), who produces architectural tarpaulin and canvas in PVC/polyester compound. This is a rather difficult formulation for recycling, since the PVC is mixed with a matrix. At the same time, Ferrari felt it was important that their material would be recyclable. The first Vinyloop installation is now operational. It is a form of mechanical rather than feedstock or chemical recycling, since the PVC matrix is not changed in the process. 

Improved ISEs. In 1980, Ammann et al.154 reported on clinical and biological applications of liquid membrane electrodes based on an ion-selective component and a suitable plasticizer in a PVC matrix for the determination of Na +, K, Ca2, Cl and H + in blood serum or whole blood and Na+ and K4 in urine. They gave extensive information on membrane compositions and selectivity... 

An r/rr/mnv -squaraine-based chemosensor 23a absorbing at 635 nm (eM = 260,000 M 1cm 1) and emitting at 665 nm signals alkaline and earth-alkaline metal ions in millimolar concentrations in acetonitrile [81]. In presence of Na+ ions, the fluorescence signal weakly increases while it significantly decreases in presence of Ca2+, Mg2+, and Ba2+ and does not change substantially upon addition of K+ ions. The same squaraine 23a and the azacrown-squaraine 23b [82] were used for Na+ and K+ sensing in a plasticized PVC matrix [83]. The squaraine derivatives exhibited fluorescence emission based optical responses to... 

Ertekin K, Tepe M, Yenigii B, Akkaya EU, Henden E (2002) Fiber optic sodium and potassium sensing by using a newly synthesized squaraine dye in PVC matrix. Talanta 58 719-727... 

The drug substance has been determined by direct potentiometric titration using chlorpromazine-sensitive electrodes [78. These consisted of an electroactive material in the membrane being either the chlorpromazine complex with either tetraphenylborate or dinonyinaphthalene sulfonate set in a PVC matrix. 2-nitrophenyl octyl ether was used as the plasticizer. 

Crown ethers [364] have proved to be an excellent choice as ionophores for the fabrication of ion sensors because of their ability to complex selectively a particular ion. The cadmium selective sensors have been fabricated from poly(vinyl chloride) (PVC) matrix membranes containing macrocyclic ionophores benzo-15-crown-5 [365], monoaza-18-crown-6 [366], dibenzo-24-crown-8 [367], dicyclohexano-18-crown-6 [368], 3,4 ll,12-dibenzo-l,6,... 

Figure 2. Experimental system for the measurement of membrane potential by a PVC matrix liquid-membrane-type electrode (reprinted with permission from Yakugaku Zasshi 1995, 115, 432. Copyright 1995 The Pharmaceutical Society of Japan).

Ion-Selective Electrodes based on Bis-Thiourea Receptors. Bis-thiourea derivatives 14, 15, and 17, which have a good membrane solubility, sufficient lipophilicity to prevent leaching into the aqueous sample solution, and a low tendency for self-aggregation in nonpolar solvents, were incorporated into PVC matrix liquid membranes for ISEs. While membrane electrodes based on the dibutyl derivative 14 gave a phosphate response almost identical to that of a conventional anion-exchanger electrode, a membrane electrode based on the phenyl-substituted bis-thiourea 15 exhibited a slightly improved phosphate response, which seems to be the result of improved complexation of phosphate in the sensor membrane. 

Figure 8. Potentiometric responses to 5 -CMP (o) and 5 -AMP ( ) by PVC matrix liquid membranes (DOP/PVC = 2 1 wt/wt) containing (a) lipophilic cation 9 (3.1 wt%) and (b) lipophilic cation 9 (3.1 wt%) plus neutral cytosine derivative 10a (1.3 wt%) (150 mol% 9 relative to 10a). Measured at pH 6.8 (0.1 M HEPES-NaOH buffer) (adapted with permission from Anal. Chim. Acta 1997, 341, 134. Copyright 1997 Elsevier Science Ltd.).

The fluorescence response of an optical sensor based on a PVC matrix liquid membrane containing receptor 22 and ionic sites [bis(2-ethylhexyl) sebacate... 

Figure 14. Potentiometric responses to simple amine guests (33-37) by PVC matrix liquid membranes, (a) Membrane based on calix[6]arene hexaester (29 (R = H)/DOS/PVC = 5 68 27 wt%). (b) Membrane based on dibenzo-18-crown-6 (32/DOS/PVC = 2 66 32 wt%). Measured in 0.1 M Tris-HCI buffer (pH 7.0) at room temperature (ca. 20 °C) (reproduced with permission of American Chemical Society from Anal. Chem. 1993, 65,1079).

Table 3. Potentiometric Selectivity Coefficients for PVC Matrix Liquid Membranes Based on Calixl6)arene Hexaester or Dibenzo-18-crown-6 ...

Figure 20. Potentiometric responses to anionic guest 78 by PVC matrix liquid membranes containing cyclophanes (74, 76,77) or acyclic reference compound (75). (a) Membrane potential as a function of pH in the presence ( ) or absence (o) of 1.00 X 10 M guest, (b) Membrane potential as a function of guest concentration at pH 5.0 (0.01 M AcONa-AcOH buffer) and room temperature (ca. 20 °C). Membrane composition DOS (95 mg) and PVC (44 mg) containing 6.2 x 10 mmol host.

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