Poly-carboxylic acid-based modifier

The chemical properties of PVAc are those of an aliphatic ester. Thus, acidic or basic hydrolysis produces poly(vinyl alcohol) and acetic acid or the acetate of the basic cation. Industrially, poly(vinyl alcohol) is produced by a base-catalyzed ester interchange with methanol, where methyl acetate forms in addition to the pol5mieric product. The chemical properties of PVAc can be modified by copolymerization. When a comonomer having a carboxylic acid group or a sulfuric acid group is used, the copolymer becomes soluble in dilute aqueous alkah or... 

Another important electroanalytieal application of modified electrodes is DNA detection [34-40]. Zhang et al. [39] produced an electrochemical DNA sensor based on silver nanoparticles/poly(trans-3-(3-pyridyl) aciylic acid) (PPAA)/multiwalled carbon nanotubes with carboxyl groups (MWCNTs-COOH) modified glassy carbon electrode (GCE). The polymer film was electropolymerized onto MWCNTs-COOH modified electrode by cyclic voltammetry, and then silver nanoparticles were electrodeposited on the surface of PPAA/MWCNTs-COOH composite film. The novel electrochemical detection method of DNA hybridization-based modified electrode has been developed with high sensitivity and selectivity. Furthermore the results of the experiment indicated that the DNA sensor is of excellent reusability. 

Jiang group developed silica/poly(divinylbenzene)-based polymeric microcapsules (PMCs) modified with three kinds of functional groups as carboxylic acid (PMC-C), sulfonic acid (PMC-S), and pyridyl groups (PMC-N), about which the PMCs displayed enhanced water retention capability even under low RH of 20%. The PMCs were well designed to have core-shell structure with controllable shell thickness, and then composite polyelectrolytes were fabricated from PMCs and chi-tosan (CS). Figure 9.9 displays the TEM images of the functionalized PMCs. 

Three generations of latices as characterized by the type of surfactant used in manufacture have been defined (53). The first generation includes latices made with conventional (/) anionic surfactants like fatty acid soaps, alkyl carboxylates, alkyl sulfates, and alkyl sulfonates (54) (2) nonionic surfactants like poly(ethylene oxide) or poly(vinyl alcohol) used to improve freeze—thaw and shear stabiUty and (J) cationic surfactants like amines, nitriles, and other nitrogen bases, rarely used because of incompatibiUty problems. Portiand cement latex modifiers are one example where cationic surfactants are used. Anionic surfactants yield smaller particles than nonionic surfactants (55). Often a combination of anionic surfactants or anionic and nonionic surfactants are used to provide improved stabiUty. The stabilizing abiUty of anionic fatty acid soaps diminishes at lower pH as the soaps revert to their acids. First-generation latices also suffer from the presence of soap on the polymer particles at the end of the polymerization. Steam and vacuum stripping methods are often used to remove the soap and unreacted monomer from the final product (56). 

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