Copolymer conductometric titration

All copolymers were prepared by solution polymerization, under adiabatic conditions, giving at least 99.9% conversions. The polymer gels were granulated and then dried at 90 °C to a residual water content of 10 to 12%. The active polymer content of each sample was calculated from the initial weight of the comonomers and the weight of the dried gel. Hydrolysis of the polymers was determined by conductometric titration to be less than 0.2% of the acrylamide charge. The molecular weight of the polymers was 8-10 million as determined by intrinsic viscosity measurements. 

The extent of hydrolysis of the copolymers was determined by conductometric titration. The increase in carboxylate content was determined by difference, before and after hydrolysis. (The AMPS content of the polymers, where measured, was determined by colloid titration with poly [diallyl dimethyl ammonium chloride].)... 

Latex No. Results of Conductometric Titration of MMA/MAA Copolymer Latexes MAA Content in the Copolymer Based on the Back-Titration Results (wt. %)... 

Using an improved conductometric titration procedure, Nishida et al. (20, 21) and Loncar et al. (22) quantitatively investigated the alkali-swelling behavior of highly carboxylated MMA-MAA copolymers. The ratio of surface... 

Copolymer resin (p-CAF) was synthesized by the condensation of p-cresol and adipamide with formaldehyde in the presence of hydrochloric acid as catalyst and using varied molar ratios of reacting monomers. A composition of the copolymers has been determined on the basis of their elemental analysis. The number average molecular weight of resins was determined by conductometric titration in non-aqueous medium. The copolymer resins were characterized by viscometric measurements in dimethylsulphoxide (DMSO), UV-visible absorption spectra in non-aqueous medium, infrared (IR) spectra, and nuclear magnetic resonance (NMR) spectra. The morphology of the copolymers was studied by scanning electron microscopy (SEM). 

The MA-VA copolymers of maleic anhydride (MA) with vinyl acetate (VA), (Chitanu et al., 2006) and MA-MMA copolymers with methyl methacrylate (MMA), (Chitanu et aL, 2007) are synthesized by free radical polymerization, purified by extraction and washed with diethyl ether. The composition is estimated by conductometric titration with aqueous O.IN NaOH in 1 1 acetone-water mixture and the molecular weight (Mw) by viscosimetric measurements in acetone at 30 °C. 

Fig. 1. Curves of conductometric (1,3) and potentiometric (2) titrations of aqueous solutions of MAn/AA copolymer (2, 3) and acetic acid with polyvinylpyrrolidone solution (l)21,67j...

The experimental results may be represented both by the titration curves or property-composition dependences. The extremums or bends on the titration curves indicate the formation of complexes and their composition. Thus, investigating the-possi-bility of complex formation in polyelectrolyte - nonionic polymer systems, one can use the methods of conductometric and potentiometric titration. The formation of interpolymer complexes in these systems, as some authors suggest18,211, is caused by a co-operative formation of hydrogen bonds between carboxy groups of the polyacid and oxygen atoms of nonionic polyvinylpyrrolidone or poly(ethylene glycol) and is therefore accompanied by an increase of pH of the solution. The typical titration curves for the system polyvinylpyrrolidone - copolymer maleic anhydride and acrylic add are shown in Fig. 1. The inflection points of the titration curves indicate the ratio at which the macromolecular components react with each other, i.e. the composition of the formed complexes. 

---