733

ISSN 1070-4272. Russian Journal of Applied Chemistry, 2006, Vol. 79, No. 5, pp. 733 �735. � Pleiades Publishing, Inc., 2006.Original Russian Text � E.E. Ergozhin, K.I. Imanbekov, 2006, published in Zhurnal Prikladnoi Khimii, 2006, Vol. 79, No. 5, pp. 744 �746.

SORPTION����������������������� �����������������������

AND ION-EXCHANGE PROCESSES

Ion Exchangers Based on Homo- and Copolymersof Vinyloxyethylamine and Glycidyl Methacrylate

E. E. Ergozhin and K. I. Imanbekov

Bekturov Institute for Chemical Science, Ministry of Education and Science of Kazakhstan Republic,Almaty, Kazakhstan

Received October 4, 2005; in final form, February 2006

Abstract�An efficient method is developed for synthesis of highly permeable ion-exchange resins throughthe reaction of glycidyl methacrylate with polyvinyloxyethylamine and its copolymers with nitrogen-contain-ing monomers with preservation of the nitrogen functional groups in the latter monomers. The synthesis condi-tions are optimized, and physicochemical and sorption properties of the resulting polymers are examined.

DOI: 10.1134/S1070427206050077

Polyvinyloxyethylamine (PVOEA, monoethanol-amine polyvinyl ether) and its copolymers with2-methyl-5-vinylpyridine (2M5VP), 4-vinylpyridine(4VP), and N-vinylpyrrolidone (NVP), containingreactive and complexing functional groups, representa particular class of water- and organo-soluble poly-mers [1, 2]. The presence of the VOEA units with pri-mary amino groups in the structure of such homo- andcopolymers provides high reactivity in polycondensa-tion with epoxy compounds (no need in additionalhardeners like di- and polyamines), thus allowingmaintenance of the complexing capacity of the tertiarynitrogen atom of the pyridine and lactam rings.

In this study we synthesized the polyfunctional ion-exchange resins by the reaction of glycidyl methacryl-ate (GMA) with VOEA homo- and copolymers con-taining the pyridine and lactam rings and charac-terized their properties.

EXPERIMENTAL

Glycidyl methacrylate, VOEA polymers, and its co-polymers with N-vinylpyrrolidone and vinylpyridines(VOEA�NVP, VOEA�4VP, and VOEA�2M5VP;VOEA : vinylpyridine = 25 : 75 mol/mol) were syn-thesized by the standard procedures [1�4].

Polycondensation of GMA with homo- and copoly-mers of VOEA was carried out in DMF in a three-necked flask equipped with a mechanical stirrer, athermometer, and a dropping funnel. The mixture wasstirred with heating to the onset of gelation. Then thegel was transferred into a porcelain bottle and curedat 60�120�C under argon. The subsequent processing

of the polymers and their physicochemical charac-terization were performed by the standard methods[5, 6].

The static sorption of the copper ions was studiedby the separate portion method. Potentiometric titra-tion was carried out on an OR-265 digital pH-meterat 25�C. The stock solution was prepared from coppersulfate (analytically pure grade). The ionic strengthof the solution (�) was varied by adding Na2SO4.The IR spectra of the as-prepared polymers and metal-containing samples were recorded on UR-20 andSpecord spectrophotometers using the KBr technique[7]. The potentiometric titration was performed usingthe separate portion method [8].

To optimize the synthetic route, we studied the ef-fects of the component ratios and curing temperatureand time.

We found that the characteristics of the final prod-ucts are influenced to a greater extent by the startingreagent concentrations and the nature of VOEA poly-mers (Table 1). In all cases, the static exchange capac-ity (SEC) and nitrogen content in the resins increasedwith increasing concentration of VOEA or its copoly-mer in the initial mixture. The SEC of the anion ex-changers is largely controlled by the nature of theVOEA polymer. The exchange capacity of the poly-electrolytes based on homo- and copolymers of VOEAincreased in the order PVOEA < VOEA�4VP <VOEA�2M5VP, which can be attributed to the factthat, among the indicated polyamines, the aliphaticone is the most reactive, allowing protection of thepyridine groups against quaternization in the course of

RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 79 No. 5 2006

734 ERGOZHIN, IMANBEKOV

Table 1. Influence of nature and ratio of starting compo-nents on SEC of resulting GMA�polyamine anion ex-changers (curing temperature 100�C; 3 h)����������������������������������������

VOEA-based� Epoxy : NH2 � cN2

, � SECHCl

polymer� initial molar �

wt %� (0.1 N HCl),

� ratio � � mg-equiv g�1

����������������������������������������PVOEA � 1.0 : 1.0 � 6.50 � 4.59

� 1.0 : 2.0 � 9.30 � 6.58� 1.0 : 3.0 � 10.75 � 7.70� 1.0 : 4.0 � 11.74 � 8.36� � �VOEA�4VP � 1.0 : 1.0 � 7.34 � 5.20� 1.0 : 2.0 � 8.80 � 6.20� 1.0 : 3.0 � 9.50 � 7.00� � �VOEA�2M5VP� 1.0 : 1.0 � 6.80 � 4.80� 1.0 : 2.0 � 8.00 � 5.70� 1.0 : 3.0 � 8.80 � 6.20� � �VOEA�NVP � 1.0 : 1.0 � 7.05 � 2.50� 1.0 : 2.0 � 8.32 � 2.95� 1.0 : 3.0 � 9.18 � 3.23

����������������������������������������

curing. This is demonstrated by the retention of theband of the low-basic pyridine ring at 1554 cm�1 andalso by the lack of the band of the quaternized hetero-cycle at 1532 cm�1. In the IR spectra of the polymers,the intensity of the bands of bending (1570 cm�1) andasymmetric (3360 cm�1) and symmetric (3290 cm�1)stretching vibrations of the N�H bond decreases,which is consistent with the reference IR data for theinitial linear polymer of VOEA and its copolymerswith 4VP and NVP [1, 2], polyvinylpyridines [7], andstrongly basic commercial anion-exchange resinsVP-1Ap and VP-100 [9].

At the optimal ratio of the starting components, westudied the effect of the curing temperature on thecharacteristics of the resulting resins. Table 2 showsthat, with increasing temperature, SEC increases. Themaximal SEC of the resins based on VOEA homo-polymer was observed at 80�C, and that of the resinsbased on VOEA�4VP, VOEA�2M5VP, and VOEA�NVP copolymers, at 100�C. Increase in the curingtime at the optimal temperature also improves SEC ofthe resins (Table 3).

As a measure for the chemical resistance of theresins we used the SEC loss after their treatment with5 N solutions of sulfuric acid or NaOH for 30 min at100�C, or with 10% H2O2 at 25�C for 24 h (Table 4).

The network polyelectrolytes based on GMA andVOEA homopolymers and copolymers with 4VP and2M5VP were found to be stable in the indicated ag-gressive media.

Table 2. SEC and nitrogen content in anion-exchangeresins obtained at various temperatures (epoxy : NH2 ini-tial molar ratio 1.0 : 2.0; curing time 3 h)����������������������������������������

VOEA-based �T, �C

� cN2, � SECHCl (0.1 N HCl),

polymer � � wt % � mg-equiv g�1

����������������������������������������PVOEA � 60 � 8.42 � 6.00

� 80 � 9.27 � 6.53� 100 � 9.30 � 6.58� 60 � 6.45 � 4.60� � �VOEA�4VP � 80 � 7.60 � 5.41� 100 � 8.80 � 6.20� 120 � 8.81 � 6.24� 60 � 6.10 � 4.35� � �VOEA�2M5VP� 80 � 7.40 � 5.24� 100 � 8.00 � 5.70� 60 � 6.65 � 2.35� � �VOEA�NVP � 80 � 7.50 � 2.60� 100 � 8.32 � 2.95

����������������������������������������

The acid�base and sorption characteristics of theresins were studied by potentiometric titration in theabsence (Fig. 1, curves 1, 3) and in the presence ofCu ions (curves 2, 4). The titration curves suggestthe polyfunctional structure of the resins based onPVOEA and its nitrogen-containing copolymers. ThepKa values estimated by the Henderson�Hasselbachequation are 8.65 and 8.90 for the resins based onPVOEA and VOEA�NVP, respectively. In the pres-ence of Cu ions, the potentiometric titration curvesshift toward lower pH values.

Table 3. SEC and nitrogen content in anion-exchangeresins at various curing times � (epoxy : NH2 initial molarratio 1.0 : 2.0; GMA : VOEA�VP = 1.0 : 1.0; curingtemperature 100�C)����������������������������������������

VOEA-based ��, h

� cN2, � SECHCl (0.1 N HCl),

polymer � � wt % � mg-equiv g�1

����������������������������������������PVOEA � 1.0 � 6.22 � 4.41

� 2.0 � 9.21 � 6.55� 3.0 � 9.30 � 6.58� 4.0 � 9.30 � 6.58

VOEA�4VP � 1.0 � 6.05 � 4.20� 2.0 � 8.40 � 6.00� 3.0 � 8.80 � 6.20� 4.0 � 8.81 � 6.24

VOEA�NVP � 1.0 � 5.56 � 1.91� 2.0 � 6.74 � 2.38� 3.0 � 8.32 � 2.95� 4.0 � 8.51 � 3.00

����������������������������������������

RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 79 No. 5 2006

ION EXCHANGERS BASED ON HOMO- AND COPOLYMERS 735

Table 4. Chemical resistance of anion-exchange resins (epoxy : NH2 initial molar ratio 1.0 : 2.0; GMA : VOEA�VP =1.0 : 1.0; curing temperature 100�C; 3 h)������������������������������������������������������������������������������������

VOEA-based polymer�

SECHCl (0.1 N HCl),�

Swellability,�Chemical resistance with respect to indicated agent, %

� � ���������������������������������������� mg-equiv g�1

� ml g�1� 5 N H2SO4 � 5 N NaOH � 10% H2O2

������������������������������������������������������������������������������������PVOEA � 9.30 � 4.50 � 95 � 96 � 91VOEA�4VP � 8.80 � 4.25 � 98 � 97 � 93VOEA�2M5VP � 8.00 � 4.20 � 98 � 97 � 94������������������������������������������������������������������������������������

The IR spectrum of the complex of the PVOEA-based resin with copper shows a low-frequency shiftby 60 cm�1 of the N�H stretching vibration band at3300 cm�1 and a decrease in the intensity of the C�O�C stretching vibration (1100 cm�1). In the case of theresin based on VOEA�2M5VP, containing Cu ions,the band at 1490 cm�1 (pyridine ring) is broadened.Furthermore, all the complexes with Cu(II) demon-strate a decrease in the intensity and a low-frequencyshift by 30 cm�1 of the stretching vibration band of thecarbonyl groups of the GMA polymer and lactam ring.

To conclude, the polycondensation of GMA withhomo- and copolymers of VOEA yields novel chelat-ing medium-basic network polymers, which could beused for recovering transition and noble metals.

CONCLUSIONS

(1) The chemical resistance of anion-exchangeresins synthesized from glycidyl methacrylate andhomo- and copolymers of vinyloxyethylamine in 5 N

v, ml

Potentiometric titration curves of anion-exchange resinsat various concentrations of Cu ions (� = 1.0): (1,2) PVOEA/GMA and (3, 4) VOEA�NVP/GMA. (v) Volumeof 0.1 N HCl consumed for titration.

solutions of sulfuric acid and NaOH is 95�98%, andthat in such a strong oxidizing agent as 10% H2O2,91�94%.

(2) The IR spectra of the resins based on the co-polymers of vinyloxyethylamine with 2-methyl-5-vin-ylpyridine and 4-vinylpyridine confirm preservation ofthe complexing pyridine groups after the reaction withglycidyl methacrylate.

(3) The pKa values of the resins based on glycidylmethacrylate and the homopolymer of vinyloxyethyl-amine or vinyloxyethylamine�N-vinylpyrrolidone co-polymer, estimated by the Henderson�Hasselbachequation, suggest the formation of medium-basicanion exchangers.

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