Polymer resin titration

The percent reaction was typically determined by elemental analysis however, in the case of cross-linked polymers, the percent reaction was also evaluated by titrating the amount of chloride liberated and by measuring the weight gain of the polymer resin. All three methods gave comparable results (within 2-3%). 

A titration curve determined in 0.03 M NaCl at room temperature has been reported in the case of cro s-linked PVA 62). The shape of the curve is similar to that of the linear polymer. Cr< >< s-linked resins of polyethylene imine structure have been used to complex heavy m, tal ions from dilute solutions. The complex formation of these resins with metal ions was not thoroughly studied on a thermodynamic basis however, the authors 63) demonstrated that, from a practical point of view, at least one of these resins in column operations was able to concentrate Cu2+, Co2+ and Ni2+ from aqueous solutions, even in the presence of high concentrations of alkali- and alkaline earth metals. 

Anchoring polymers are prepared from chloromethylated styrene-divinylbenzene copolymers of either 1 equiv Cl/g or 4 equiv Cl/g capacity. These resins arc stirred for 24 h in refluxing CHC13, with either 1,4-diazabicyclo[2.2.2]octane, hexamethylenetetramine, or TMEDA. The polymers are filtered off, washed with ClIClj, acetone and Et20, then dried overnight under vacuum at 25 °C. Nitrogen elemental analysis and chloride ion titration gives a value of 80-90% quaternarization. 

The Second polymeric substrate with a longer chain length was prepared by the Friedel-Crafts alkylation of Bio-Bead SXl and AICI3 with 4-chlorobutyric acid in nitrobenzene for 5 hours at 80 C. The resin was washed with AcOH, 61 HCl-dioxane (1 1), HaOrdioxane (1 1), dioxane and CH2CI2. Titration was effected as stated earlier 0.9 mequiv of carboxyl per gram of polymer was determined. 

Since Merle s data indicate that deviation from ideality of the charged species is negligible in the gel, contrary to expectations derived from the preceeding analysis, we reexamined the potentiometric properties of the flexible carboxymethyldextran gel system (Sephadex CM-50) studied by Merle. We also carried out a parallel investigation of the much more rigid PM A resin (IRC-50) cross-linked with approximately 5 wt % divinyl benzene. The titrations of these polymers with standard b,ase were made in the presence of sodium polystyrene sulfonate. The pH and pNa of the solution phase and the volume (Vp) of the gel (resin) phase were measured at selected a values covering the complete neutralization range. 

Determination of carboxyl capacity For the determination of carboxyl content 100 mg of the resin was equilibrated with HCl (0.2 mol L, 10 mL) for 24 h with magnetic stirring. The resin samples were filtered, washed with distilled water to remove unreacted HCl and the filtrate was titrated with NaOH (0.2 mol L ) to a phenolphthalein end point. The polymer contains -3.3 mmol g carboxylic acid groups. 

Determination of acid capacity Acid capacity is measured by immersing a known amount of centrifuged polymer in the protonated form in 100 mL of 0.1 M NaOH solution for 24 h and titrating the resultant solution with 0.1 M HCl. pATa of the resins is measured using ca. 0.1 g (dry weight) of polymer equilibrated with 45 mL of 1 M KCl. To this stirred (200 rev. min ) suspension 0.15 mL of 0.1 M KOH is injected every 90 min using a Kiihn-and-Bayer liquid processor. The pH is recorded every 15 min. An acid capacity of 6 mmol g was determined. 

If a polymer(s) or resin(s) is dissolved in a true solvent and then titrated with a known diluent, there comes a point when the binder just starts to precipitate out of solution. In most cases, this point is sharply defined and the solution takes on a definite turbidity. The composition of the solvent at this point is assumed to be able to just dissolve the binder and its solubility parameters therefore indicate the absolute minimum acceptable solvent power at this point. By performing this titration and calculation with a variety of solvents and diluents, the limits of solubility of the binder are accurately defined. The construction of a map is then quite straightforward by using the following procedure ... 

Other work on the determination of water in polymers includes water in anionic resins [4] and polyethylene terephthalate [5] by Karl Fischer titration, water in polyesters [6] and in polyamides [6, 7], aqueous polymers [7-9] and in polyesters [10]. 

When the functionalized polymer contains acidic or basic groups, such as those in ion-exchange resins, the acid-base titration methods are the most suitable for functional group determination. Such methods are well-established (Helfferich, 1962), In one report (Schou et aL, 1975), the free amino group in an unblocked resin-peptide was determined by nonaque-ous titration with acid. Similarly, histidine incorporation could be deter-... 

Both linear and cross-linked monodisperse latexes of polystyrene in the size range 0.1 - 1.2y have been prepared by persulfate-initiated emulsion polymerization (6,7,8), and the size and size distributions of the polymer spheres detennined by electron microscopy. Free electrolyte was removed by a mixed-bed ion exchange resin, and surface charge measured by conductometric titration against standard base. Redispersion in organic media was effected by successive dialyses, first with methanol and finally against the desired solvent. 

A suitable method for determining the anhydride group is titration with aqueous potassium hydroxide in pyridine after previous esterification of the carboxyl group with diazomethane. This esterification is carried out in diethyl ether methanol (9 + 1). After methylation, which takes about 10 minutes for 0.5 g of sample, solvents are removed by evaporation and a portion of the derivatised polymer is dissolved in pyridine and titrated. In the IR spectra of the resin before and after methylation, the absorption band of the acid group at 1710 cm (5.84 pm) disappears and a carbonyl band of the ester at 7104 cm (5.74 pm) is formed. The acid content of the sample is found from the difference in titres of an unmethylated and a methylated product. 

Potassium persulfate, 295 Potentiometic titration MA-grafted polymers, 472 MA-polymers, 260, 282, 291, 427, 432, 438, 442 Povimal ST, SMA copolymers, 426 Povimalya resins, MA-vinyl acetate copolymers, 440... 

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