Linear-dendritic block copolymers as a green scale inhibitor for calcium carbonate in cooling water systems

Water-soluble monomer APEG-PG-(OH)n were produced and the Structure of APEG-PG-(OH)5 were identified by ¹H-NMR. APEG-PG-(OH)n were copolymerized with maleic anhydride (MA) to synthesize no phosphate and nitrogen free calcium carbonate inhibitor MA/APEG-PG-(OH)n. The structure and thermal property of MA/APEG-PG-(OH)5 were characterized and measured by ¹H-NMR, GPC and TGA. The observation shows that the dosage and n value of MA/APEG-PG-(OH)n plays an important role on CaCO₃ inhibition. MA/APEG-PG-(OH)5 displays superior ability to inhibit the precipitation of calcium carbonate, with approximately 97% inhibition at a level of 8 mg/L. The effect on formation of CaCO₃ was investigated with combination of SEM and XRD analysis.     

Synthesis and evaluation of an environment-friendly terpolymer CaCO3 scale inhibitor for oilfield produced water with better salt and temperature resistance

The CaCO₃ deposits exist widely in the petroleum industry, causing severe damage to the equipment and production. In this article, a novel environment-friendly terpolymer scale inhibitor Poly (maleic anhydride - acrylic acid -2- acrylamide -2- methyl propanesulfonic acid) (P(MA-AA-AMPS))-containing carboxylic acid group, sulfonic acid group, and amide group was synthesized. The structure and molecular weight were characterized by FTIR, ¹H-NMR, and GPC. The static scale inhibition experiment was conducted to study the influence of factors such as the dosage, monomer ratio, temperature, pH, Ca²⁺ concentration, and concentration on the scale inhibition performance of CaCO₃. The results show that when the monomer ratio is 2.0:1.0:0.5 and the dosage is 20 mg L⁻¹, the maximum scale inhibition efficiency is 95.52%. Even when Ca²⁺ concentration exceeds 1200 mg L⁻¹ and temperature reaches 90 °C, the scale inhibition efficiency is still larger than 80%. The results of SEM and XRD show that P(MA-AA-AMPS) interferes with the growth of CaCO₃ crystal by adsorption, dispersion, and chelation. The effect leads to changes in the morphology of CaCO₃ crystals, the size of which drops from 20–30 μm to 2–5 μm. The P(MA-AA-AMPS) can transform CaCO₃ from stable calcite crystals to unstable aragonite and vaterite. Finally, the formation of CaCO₃ scale is well inhibited. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48460.     

绿色无磷高效阻垢缓蚀剂的制备及性能研究

以衣康酸(IA)、烯丙基磺酸钠(SAS)、乙酸乙烯酯(VAC)为单体聚合得到IA-SAS-VAC共聚物,考察了单体配比、引发剂量、反应时间和反应温度对共聚物阻垢效果的影响;采用扫描电镜和X射线衍射仪对垢样进行了分析。结果表明,当单体配比n(IA)∶n(SAS)∶n(VAC)=2∶1∶4时,引发剂投加量为单体总质量的10%,相对分子质量调节剂异丙醇投加量为单体总质量的12%时,在90℃的反应温度下控制反应时间为3 h,共聚物投加量为20 mg/L,此时对于碳酸钙阻垢率达到92.6%;当投加量为50 mg/L时,缓蚀率达到88.9%。对阻垢剂的阻垢机理进行了扫描电镜和X射线衍射研究。     

Preparation and Application of Polymers as Inhibitors for Calcium Carbonate and Calcium Phosphate Scales

The scale inhibitor was prepared based on itaconic acid (IA), styrene p-sulfonic sodium (SSS), maleic anhydride (MA), and acrylamide (AM) as monomers, and ammonium persulfate as an initiator by the free-radical polymerization. The structure of the polymer was characterized by FT-IR and UV-Vis spectroscopy. Using the static experiment method, the scale inhibition efficiency to CaCO₃, the effects of some factors (concentration of polymer, time, concentration of Ca²⁺, pH value, concentration of HCO₃ ^?, and temperature) were investigated. Using the malachite green photometric method, the scale inhibition efficiency to Ca₃(PO₄)₂ and the effects of some factors (concentration of polymer, time, Ca²⁺, pH, temperature, and the concentration of PO₄ ^3?) were also investigated. The experimental results showed that the polymer had an excellent efficiency of scale inhibition and a resistance rate of calcium carbonate scale up to 96.67%, a resistance rate of calcium phosphate scale up to 92.5%, and could be used in the system of high-temperature and high-hardness water. The polymer had good dispersing ability with respect to iron.     

Evaluation of maleic acid-based copolymers containing polyoxyethylene ether as inhibitors for CaCO3 scale

Polymer scale inhibitors have been widely used to reduce the loss caused by mineral scaling in circulating cooling water systems. In this article, four maleic acid-based copolymers [hydrolyzed polymaleic anhydride (HPMA)-AEO] containing different fatty alcohol polyoxyethylene ether (such as AEO-9, AEO-10, AEO-15, and AEO-20) are prepared by the way of free-radical copolymerization and characterized using Fourier transform infrared (FTIR), ¹H NMR, and gel permeation chromatographic (GPC) techniques. The effects of HPMA-AEO on CaCO₃ scale are studied in several aspects (such as dose, Ca²⁺ concentration, temperature, inhibition time, pH, the ratio of EO:carboxyl, and the relative supersaturation of CaCO₃ solution) by static experiments. The CaCO₃ scaling process with dosing of HPMA-AEO-9 is investigated under dynamic tests. CaCO₃ deposits and precipitate in the presence of HPMA-AEO-9 are analyzed using scanning electronic microscope (SEM) and X-ray diffraction (XRD). The results show that the performance of HPMA-AEO against CaCO₃ scale highly depends upon the ratio of EO:carboxyl; the introduction of AEO group can significantly improve the performance of HPMA-AEO to tolerate high alkalinity, high hardness, and high temperature; the presence of HPMA-AEO-9 can obviously affect the CaCO₃ scaling process on the tube wall through interfering with nucleation process and crystal growth process and significantly alter the surface morphology and crystal form of CaCO₃ deposits. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47470     

Carboxylate-Terminated Double-Hydrophilic Block Copolymer Containing Fluorescent Groups: An Effective and Environmentally Friendly Inhibitor for Calcium Carbonate Scales

Allyloxy polyethoxy ether (APEG) and succinic anhydride were used to prepare allyloxy polyethoxy carboxylate (APEL). 8-hydroxy-1,3,6-pyrene trisulfonic acid trisodium salt (PY) was reacted with allyl chloride to produce fluorescent monomer 8-allyloxy-1,3,6-pyrene trisulfonic acid trisodium salt (PA). APEL and PA were copolymerized with acrylic acid (AA) to synthesize PA tagged no phosphate and nitrogen free CaCO₃ inhibitor AA-APEL-PA. Structures of PA, APEG, APEL, and AA-APEL-PA were carried out by FT-IR and ¹H-NMR. The observation shows that the dosage of AA-APEL-PA plays an important role on CaCO₃ inhibition. The effect on formation of CaCO₃ was investigated with combination of scanning electronic microscopy and X-ray powder diffraction analysis. Relationship between AA-APEL-PA's fluorescent intensity and its dosage was studied. Correlation coefficient r of AA-APEL-PA's fluorescent intensity and its dosage is 0.9998. AA-APEL-PA can be used to accurately measure polymer consumption on line besides providing excellent CaCO₃ inhibition.     

MAPS四元共聚物硅垢防垢剂的合成与评价

以马来酸酐(MA)、丙烯酸(AA)、聚乙二醇(PEG)、甲基丙烯磺酸钠(SMAS)为原料,采用水溶液聚合法得到了一种四元共聚物(MAPS)硅垢防垢剂。通过单因素实验并以硅垢防垢率为评价指标来确定共聚物最佳合成条件:单体总质量分数为30%,n(MA)∶n(AA)∶n(SMAS)∶n(PEG)=1∶1∶0.4∶0.03,引发剂投加量为8%,反应温度为85℃,反应时间为3 h。在防垢剂加量为100 mg/L时,硅垢防垢率为76%;在防垢剂投加量为60 mg/L时,碳酸钙垢防垢率为91%。     

Rheology of poly(n‐butyl methacrylate) and its composites with calcium carbonate

Poly(n‐butyl methacrylate) (PBMA) composites with calcium carbonate (CaCO₃) were prepared by in situ radical copolymerization of butyl methacrylate (BMA) and methacrylic acid (MA) with precipitated calcium carbonate. To compare the different rheological behaviors of the monomer mixtures with CaCO₃ and the composites, the steady and dynamic viscosities of BMA/MA/CaCO₃ and poly(BMA/MA/CaCO₃) were measured by means of steady and oscillatory shear flows. The viscosity of the mixture BMA/MA/CaCO₃ was found to increase evidently with the increasing of CaCO₃%. The influence of MA% on viscosity of BMA/MA/CaCO₃ was slight. During the in situ polymerization, the viscosity of the reacting system was measured to be enhanced by a factor of about 10⁴ from the monomer/CaCO₃ mixture to composites. The dependency of zero‐shear viscosity on molar mass of PBMA was also investigated. The relation between the zero‐shear viscosity and molar mass is η₀ = 10^?15 M_w^3.5. The evolution of the viscosity with the temperature for both PBMA and its composites was obtained and time–temperature superposition was used to build master curves for the dynamic moduli. The flow activation energies were found to be 115.0, 148.6, and 178.7 kJ/mol for PBMA, composite PBMA/CaCO₃ (90/10), and PBMA/MA/CaCO₃ (89/1/10), respectively. The viscosity of the composites containing less than 10% CaCO₃ was lower than that of pure PBMA with the same molar mass. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1376–1383, 2003     

Antiscaling properties of novel maleic‐anhydride copolymers prepared via iron (II) – chloride mediated ATRP

A class of maleic anhydride copolymers (YMR‐A series) with a narrow molecular weight distribution between 500–1500 and a polydispersity of 1.0–1.11 was obtained from n‐alkylacrylamide and maleic anhydride monomers via atom transfer radical polymerization. The monomer conversion reached about 71% corresponding to 1:4 [FeCl₂] to [SA] molar ratios for (AAH/MA) copolymer initiated by CPN whereas for the polymerization initiated by MCPN the conversion reached 51.9% under similar condition showing better performance of CPN initiator. Resultant polymers were characterized by means of ¹H‐NMR and ¹³C‐NMR. The inhibition behavior of these YMR‐A polymers against CaCO₃ and CaSO₄ was evaluated using static scale inhibition method. The inhibition efficiency on the calcium carbonate scale is much higher and even with 5 ppm dosage level the efficiency is around 99.33 % at pH 10.45 and temperature 70°C, where as for calcium sulfate scales the inhibition efficiency, is lower and 99.9% inhibition is observed at 7–9 ppm level. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39827.     

Preparation of carboxy sulfonic acid-containing copolymer scale inhibitors and their scale inhibition effect on CaCO3

Free radical polymerization was selected to obtain a promising copolymer scale inhibitor IA-AM-SAS with good water solubility and temperature and salt resistance, which is suitable for the treatment of surface pipeline water in oil fields, using itaconic acid (IA), acrylamide (AM), and sodium acrylsulfonate (SAS) as the monomers. The structure of the synthesized copolymer was verified by Fourier transform infrared spectroscopy and nuclear magnetic resonance hydrogen spectroscopy. Thermogravimetric results showed that the copolymer does not undergo significant thermal degradation at temperatures below 356°C, indicating that the copolymer has good thermal stability. The molecular weights of the polymers at different monomer ratios were measured using gel permeation chromatography and the relationship between the molecular weights and scale inhibition performance was discussed. The results showed that the scale inhibition effect was best when the monomer molar ratio n(IA): n(AM): n(SAS) was 0.5:2:1.5 and the number of average molecular weight of the prepared copolymer was 7712 g/mol, and the inhibition efficiency of CaCO₃ was 84.02% when IA-AM-SAS was at a concentration of 30 mg L⁻¹, and the inhibition rate was measured by the standard of static scale inhibition test in the oilfield measured. The range of conditions (PH, Ca²⁺ concentration, water temperature, and time) of the static scale inhibition test was then expanded using a one-way controlled variable experiment to explore the performance of IA-AM-SAS scale inhibitors under different water quality conditions. The scale inhibition mechanism was explored by scanning electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy. Briefly, the combination of multiple functional groups enables IA-AM-SAS to be applied in complex and challenging environments.     

Complex-radical copolymerization of <Emphasis Type="Italic">N-</Emphasis>vinyl pyrrolidone with isostructural analogs of maleic anhydride

Radical copolymerizations of N-vinyl-2-pyrrolidone (VP) with isostructural analogs of maleic anhydride (MA), such as citraconic anhydride (CA) and N-substituted maleimides [maleimide (MI), N-ethylmaleimide (EMI) and N-phenylmaleimide (PhMI)] were studied. Compositions of copolymers synthesized in a wide range of monomer feed ratios were determined by alkali titration (for anhydride copolymers), FTIR and ¹H NMR spectroscopy using 1495 and 630 cm^-1 (for VP-MI), 1289 and 1225 cm^-1 (for VP-EMI) and 1050 and 3067 cm^-1 (for VP-PhMI) analytical bands and integral areas of CH₂ (pyrrolidone ring) and CH (MI), CH₃ (EMI) and CH= (benzene ring in PhMI) groups, respectively. Electron-donor VP monomer was found to have substantially different reactivities in the radical copolymerization with MA, CA and N-substituted (H, C₂H₅ and phenyl) malemides as electron-acceptor comonomers. Effects of H-bonding and N→O=C coordination on the monomer reactivity ratios were evaluated. Tendency to alternation of the monomer pairs increases in the order of VP–MA > VP–CA > VP-MI > VP-PhMI > VP-EMI. Structure-thermal property-relationship for the synthesized copolymers was also studied.     

Calcium carbonate inhibition by a phosphonate-terminated poly(maleic-co-sulfonate) polymeric inhibitor

The precipitation of calcium carbonate scale on heat transfer surfaces widely occurs in numerous industrial processes. For the control of calcium carbonate scale and in response to environmental guidelines, the new low phosphonic copolymer was prepared through reaction of maleic anhydride with sodium p-styrene sulfonate in water with redox system of hypophosphorous and hydrogen peroxide as initiator. The anti-scale property of the low phosphonic copolymer towards CaCO₃ in the artificial cooling water was studied through static scale inhibition tests, and the effect on formation of CaCO₃ was investigated with combination of scanning electronic microscopy (SEM), X-ray powder diffraction (XRD) analysis and Fourier transform infrared spectrometer, respectively. The results showed that the low phosphonic copolymer was excellent calcium carbonate scale inhibitor in artificial cooling water. The crystallization of CaCO₃ in the absence of inhibitor was rhombohedral calcite crystal, whereas a mixture of calcite with vaterite crystals was found in the presence of the low phosphonic copolymer. For actions of carboxyl and phosphonic acid groups, the calcite was inhibited and the metastable vaterite was stabilized in the presence of the low phosphonic copolymer during the CaCO₃ formation process.     

Studies of the Effect of Comonomers on the Microstructure of Polyacrylonitrile in Radical Polymerization Using NMR Spectroscopy

Abstract

The free radical polymerization method has been employed to synthesize homopolymers of acrylonitrile (AN), its copolymers with methylacrylate (MA) and terpolymers containing itaconic acid (IA) in homogeneous solution (aqueous solution of sodium thiocyanate and dimethylsulfoxide media) and aqueous redox slurry system. ¹³C NMR was used to characterize these polymers in terms of steric configurations in order to study the effect of co and ter monomers on microstructure of polyarylonitrile both at low and high conversions. The study showed no significant change in microstructure of polyacrylonitrile on the introduction of MA and IA. Different techniques of polymerization for ACN-MA-IA had no effect on the microstructure of terpolymer. ¹H NMR and IR techniques were used to determine the composition of copolymers and a good agreement was observed between the results from the two techniques. The presence of unsaturated carboxylic acid monomer (IA) was confirmed by ¹H NMR.     

Study on Calcium Scales Inhibition Performance in the Presence of Double-Hydrophilic Copolymer

Novel double-hydrophilic block copolymers, acrylic acid (AA)-2-acrylamido-2-methyl-propane sulfonate (AMPS)-oxalic acid-allypolyethoxy carboxylate (APEM) was specially designed and synthesized from allyloxy polyethoxy ether (APEG) to inhibit the precipitation of CaCO₃ and CaSO₄. The structure of the copolymer was characterized by FT-IR and H¹-NMR. Using the static experiment method, the scale inhibition efficiencies for CaCO₃ and CaSO₄ scale were investigated. It was shown that AA-AMPS-APEM exhibited excellent ability to control inorganic minerals scales, with approximately 97.1% CaSO₄ inhibition and displayed significant ability to prevent the formation of CaCO₃ scales. The synthesized AA-AMPS-APEM was also compared with that of current commercial inhibitors. The effect of the copolymer addition on the crystals of CaCO₃ and CaSO₄ scales morphology and structures were examined through scanning electron microscope (SEM), transmission electron microscope (TEM), and X-ray diffraction studies (XRD). It proved that great changes in the size and morphology of the calcium scales took place under the influence of AA-AMPS-APEM. The proposed inhibition mechanism suggests the formation of complexes between the side-chain carboxyl groups of AA-AMPS-APEM and calcium ions on the surface of inorganic minerals, and the excellent solubility of complexes resulted from a number of hydrophilic polyethylene glycol (PEG) and sulfonic group (-SO₃H) group.     

Hyperbranched polyesters with carboxylic acid functional groups for the inhibition of the calcium carbonate scale

Scale deposits exist widely in industrial water‐cooling systems and oil‐production systems, causing severe damage to the equipment. The most effective way to prevent the formation of scale has been to use an inhibitor. The use of a hyperbranched polymer as an inhibitor, however, has rarely been reported. In this study, we prepared a hydroxyl‐terminated hyperbranched polyester (HBPE–OH) with trimethyloypropane as the core and 2,2‐bis(hydroxymethyl)propionic acid as an AB₂ monomer. The HBPE–OH was then modified with succinic anhydride to obtain the carboxyl‐terminated hyperbranched polyester (HBPE–COOH). The effects of the dosage, Ca²⁺ concentration, pH value, and temperature of the system on the inhibition efficiency were investigated when HBPE–COOH was used as an inhibitor of calcium carbonate (CaCO₃) scale. HBPE–COOH acted as a good antiscaling inhibitor for CaCO₃; when the polyester concentration was 200 mg/L, the scale inhibition rate exceeded 70%. Scanning electron microscopy and X‐ray powder diffraction demonstrated that the mechanism of inhibition was the disturbance of the growth of the crystals and modification of the crystal morphology by the hyperbranched polyester. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46292.     

Synthesis and properties of novel fluorescent‐tagged polyacrylate‐based scale inhibitors

The two fluorescent monomers N ‐allyl‐4‐methoxy‐1,8‐naphtalimide ( F1 ) and N ‐allyl‐2‐(6‐hydroxy‐3‐oxo‐3H ‐xanthen‐9‐yl)benzamide (N ‐allylamidefluorescein, F2 ) have been synthesized and then conjugated to either polyacrylate (PAA) or to a co‐polymer of fumaric and acrylic acids (MA‐AA) to give four novel fluorescent‐tagged antiscalants: nonbiodegradable PAA‐F1, PAA‐F2 and biodegradable MA‐AA‐F1 , MA‐AA‐F2 . All four reagents demonstrate the fluorescence intensity suitable for inhibitors monitoring with a detection limit within 0.40 mg dm^?3. A good linear relationship between antiscalant fluorescent intensity and its dosage is detected. PAA‐F1, PAA‐F2, MA‐AA‐F1, and MA‐AA‐F2 can be used for corresponding scale inhibitor content on‐line measurement. For some antiscalants, the fluorescence is found to be dependent on the background heavy metal ions normally present in the cooling water. This effect is explained by the corresponding complexes formation. PAA‐F1, PAA‐F2, MA‐AA‐F1, and MA‐AA‐F2 revealed a good antiscaling activity toward CaCO₃ and CaSO₄ deposition, comparable with that one of commercial polyacrylates. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45017.     

Toughening effect of comonomer on acrylic denture base resin prepared via suspension copolymerization

In this article, three copolymers used as denture base resins were prepared via suspension copolymerization using butyl acrylate (BA), butyl methacrylate (BMA), or methyl acrylate (MA) with methyl methacrylate (MMA), respectively. The homopolymers and copolymers were characterized by ¹³C nuclear magnetic resonance (¹³C NMR). The influence of the three comonomers on the mechanical property was investigated in details and the fracture surfaces of copolymer specimens were examined using scanning electron microscopy (SEM). Meanwhile, the T_g values of three copolymers were examined by differential scanning calorimetry (DSC). The results indicate that, poly(methyl methacrylate) (PMMA) copolymers with BA, BMA, or MA have been successfully prepared via suspension copolymerization. The presence of BA, BMA, or MA could improve the mechanical property especially the impact strength, the toughness of the materials was remarkably improved. The toughening effect of BMA monomer is most significant. When the content of BA is 2 wt %, the flexural strength improves by 51% and the impact strength improves by 81.3%. The T_g values of three copolymers all decrease. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

改性聚乙二醇多磺酸基水处理剂的制备及性能

以过硫酸铵为引发剂,以马来酸酐改性聚乙二醇得到的聚乙二醇酯(PEGMA)、乙烯基磺酸钠(SVS)、丙烯酸(AA)为单体,通过水相自由基共聚反应制备目标共聚物PEGMA-SVS-AA。考察了聚合工艺对其阻碳酸钙垢性能的影响,利用红外光谱对共聚物结构进行表征,得到最佳聚合反应条件为:n(PEGMA)∶n(SVS)∶n(AA)为1∶3∶5,过硫酸铵用量为单体总质量的6%,反应时间2.5 h,控制反应温度为80℃。在该条件下制备的聚合物PEGMA-SVS-AA在模拟工业生产循环冷却水条件下,其阻碳酸钙垢率达到89%。使用XRD和SEM对碳酸钙垢进行了表征,该水处理剂不仅改变了碳酸钙的形貌而且改变了碳酸钙的晶型。     

Kinetic study of radical polymerization. VII. Investigation into the solution copolymerization of acrylonitrile and itaconic acid by real‐time 1H NMR spectroscopy

Free radical solution copolymerization of acrylonitrile (AN) and itaconic acid (IA) was performed with DMSO‐d₆ as the solvent and 2,2′‐azobisisobutyronitrile (AIBN) as the initiator. Weight ratio of the monomers to solvent and molar ratio of initiator to monomers were constant in all experiments. The initial comonomer composition was the only variable in this study. On‐line ¹H NMR spectroscopy was applied to follow individual monomer conversion. Mole fraction of AN and IA in the reaction mixture (f) and in the copolymer chain (F) were measured with progress of the copolymerization reaction. Overall monomer conversion versus time and also compositions of monomer mixture and copolymer as a function of overall monomer conversion were calculated from the data of individual monomer conversion versus time. Total rate constant for the copolymerization reaction was calculated by using the overall monomer conversion versus time data and then k_p/k_t^0.5 was estimated. The dependency of k_p/k_t^0.5 on IA concentration was studied and it was found that this ratio decreases by increasing the mole fraction of IA in the initial feed. The variation of comonomer and copolymer compositions as a function of overall monomer conversion was calculated theoretically by the terminal model equations and compared with the experimental data. Instantaneous copolymer composition curve showed the formation of alternating copolymer chain during copolymerization reaction. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3253–3260, 2007     

Poly(butyl methacrylate-co-methacrylic acid) Copolymers with Calcium Carbonate Supramolecular Networks

Poly (butyl methacrylate-co-methacrylic acid) copolymers/calcium carbonate (CaCO₃) composites were synthesized by radical polymerization. Ca²⁺ cationic sites, present at the CaCO₃ surface, in interaction with carboxylate groups from polymer chains structured the material, particularly above the glass transition temperature. The composites were studied by transmission electron microscopy, X-ray diffraction, and dynamic mechanical analysis. Multiplets and clusters were detected. The material's behavior is principally controlled by the methacrylic acid (MA) content in the copolymer chain and CaCO₃/MA ratio. Under well-defined conditions, ionic cross-linked materials were obtained.