Water-Soluble Terpolymer-Mediated Calcium Carbonate Crystal

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Water-Soluble Terpolymer-Mediated Calcium Carbonate Crystal Modification Ranjith Krishna Pai,*,† Sabine Hild,† Andreas Ziegler,‡ and Othmar Marti† Department of Experimental Physics, University of Ulm, D-89069 Ulm, Germany, and Central Facility for Electron Microscopy, University of Ulm, D-89069 Ulm, Germany Received December 1, 2003. In Final Form: January 29, 2004 The structure of the polymeric substrate plays an important role in the nucleation of calcium carbonate crystals. In this study a synthetic water-soluble poly(acrylamide-co-2-acrylamido-2-methyl-1-propane sodium sufonate-co-n-vinyl pyrrolidone) was found to be a substrate favoring the nucleation of polymorphs of calcium carbonate crystals under specific experimental conditions. Morphological characterization of the polymorphs was done using atomic force microscopy, scanning electron microscopy, energy dispersive spectroscopy, FTIR analysis, and X-ray diffraction. If calcium carbonate is precipitated in the presence of terpolymer, a remarkable increase in nucleation density (number of crystals per unit area) was observed. Stacked crystals of rhombohedral morphology that formed may be due to the presence of sodium sulfonate groups on the terpolymer. However, in the presence of poly-L-aspartic acid, almost all crystals are hollow and have needlelike or plate like morphology was formed. This change in calcium carbonate morphology can be explained by the variation of the polymer conformation, if poly- L-aspartic acid is present.

Introduction Calcium carbonate is one of the most common and widely dispersed minerals, occurring as limestone, chalk, and also biominerals. Calcium carbonate crystallizes into three different polymorphs: calcite, the rhombohedral polymorph that is thermodynamically most stable form,1 followed by aragonite, which is orthorhombic,1-3 and vaterite, the hexagonal form that is least stable1,4 and is synthesized by direct precipitation.5 Water chemistry parameters such as pH and ionic strength have significant effects upon the form of calcium carbonate, which will precipitate from supersaturated solution. In terms of fouling, calcite deposits tend to be tenacious. Under atmospheric conditions aragonite is metastable and usually spontaneously undergoes a structural change to form calcite.6 When precipitation is carried out at ambient conditions, it is normal to form vaterite, which gets transformed to the stable calcite form, especially in the presence of moisture. This transformation of vaterite to calcite has been observed by Chakraborty et al.,7 (1994) who studied the continuous precipitation of calcium carbonate in a MSMPR reactor, using calcium nitrate and sodium carbonate solutions. There have been previous attempts to study the effect of additives on crystallization of calcium carbonate such as in the presence of amino acids8 and surface modifiers.9 * To whom correspondence should be addressed. E-mail [email protected]. † Department of Experimental Physics. ‡ Central Facility for Electron Microscopy. (1) Leeuw, Nora H. de, Parker Stephen C. J. Phys. Chem. B 1998, 102, 2914-2922. (2) Litvin, A. L.; Samuelson, L. A.; Charych, D. H.; Spevak, W.; Kaplan, D. L. J. Phys. Chem. 1995, 99 (32), 12065-1268. (3) Wong, K. K. W.; Brisdon, B. J.; Heywood, B. R.; Hodson, A. G. W.; Mann, S. J. Mater. Chem. 1994, 4 (9), 1387-1392. (4) Archibald, D. D.; Qadri, S. B.; Gaber, B. P. Langmuir 1996, 12, 2 (2), 538-546. (5) Davies, P.; Dollimore, D.; Heal, G. R. J. Therm. Anal. 1978, 13 (3), 473-487. (6) Sheikholeslami, R.; Ong, H. W. K. Desalination 2003, 157, 217234. (7) Chakraborty, D., Agarwal, V. K., Bhatia, S. K. and Bellare, J. Ind. Eng. Chem. Res. 1994, 33 (9), 2187-2197.

The presence of even a small amount of additive can greatly influence the crystallization process. Polycarboxylic acids such as polymaleimide greatly affect calcium carbonate crystallization.10 Levi et al.11 tested a series of aspartic acid and leucine or glutamic acid and leucine containing synthetic peptides [poly(Asp-Leu), poly(Leu-Asp-Asp-Leu), poly(Glu-Leu), poly(Leu-Glu-Glu-Leu), poly(Asp), and poly(Glu)] as models to study the selective nucleation of calcite/ aragonite polymorphism in mollusk shells. Their observation revealed that the polymorph specificity depends on the amino acid sequence, the conformation of specific peptides or proteins and the microenvironment of crystal nucleation and growth. A number of approaches12,13 have been made to synthesize specific polymorphs of CaCO3 in various forms. Experimental investigation have shown that polymeric substrate selectively induce the formation of sparingly soluble salts.14-16 Verdoes et al.17 found that the presence of sulfonic groups on copolymers can promote the formation and stabilization of vaterite in aqueous supersaturated calcium carbonate solution. Dalas et al.18 examined the effectiveness of carboxylate group containing polymers for the induction of the overgrowth of calcium carbonate (8) Manoli, F.; Kanakis, P.; Malkaj, P.; Dalas, E. J. Cryst. Growth 2002, 1-3, 363-370. (9) Agnihotri, R.; Mahuli, S. K.; Chauk, S. S.; Fan, L. S. Ind. Eng. Chem. Res. 1999, 38, 2283-2291. (10) Parminder Agarwal and Kris A. Berglund J. Cryst. Growth 2003, 1-6. (11) Levi, Y.; Albeck, S.; Brack, A.; Weiner, S.; Addadi, L. Chem. Eur. J. 1998, 4, 389-396. (12) Falini, G.; Femani, S.; Gazzano, M.; Ripamonti, A. Chem. Eur. J. 1998, 4, 1048-1052. (b) Levi; Y.; Albeck, S.; Brack, A.; Weiner, S.; Addadi; L. Chem. Eur. J. 1998, 4, 389-396. (13) Ku¨ther, J,; Seshadri; R.; Knoll, W.; Tremel, W. J. Mater. Chem. 1998, 8, 641-650. (14) Dalas, E.; Kallitsis, J.; Koutsoukos, P. G. Colloids Surf. 1991, 53, 197. (15) Dalas, E.; Kallitsis, J.; Koutsoukos, P. G. J. Cryst. Growth 1988, 89, 287. (16) Kallitsis, J.; Koumanakos, E.; Dalas, E.; Sakkopoulos, S.; Koutsoukos, P. G. Chem. Commun. 1989, 1147. (17) Verdoes, D.; van Landschoot, R. C.; van Rosmalen, G. H. J. Cryst. Growth 1990, 99, 1124. (18) Dalas, E.; Klepetsanis, P.; Koutsoukos, P. G. Langmuir 1999, 15, 8322-8327.

10.1021/la0362526 CCC: $27.50 © 2004 American Chemical Society Published on Web 03/06/2004

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Figure 1. Chemical structure of synthetic water-soluble terpolymer.

from aqueous supersaturated solutions. Faster crystallization at elevated temperatures (60 °C) yielded almost regular rhombohedrons, indicating that the crystallization speed is an important factor for the successful blocking of crystal growth at distinct faces by polymer adsorption.19 Higher polymer concentrations yielded polydisperse spherical CaCO3 crystals in a fast double jet crystallization process, which were found to be a superstructure of 2030 nm subcrystals.20 This result underlines the importance of polymer concentration with respect to the obtained crystal morphology and also confirmed that crystallization speed may play a role. The controlled crystallization of CaCO3 with PEO-block-PMAA was studied by H. Co¨lfen et al.21 Here the effect of pH and, thus, strength of the polymer/mineral interaction, polymer and CaCO3 concentration, and concentration of added, low-molar mass electrolyte were investigated systematically. Various morphologies,22 such as rodlike, peanut-like, dumbell-like, spherical, and ellipsoidal, were prepared, and general influences of the various experimental parameters onto the obtained CaCO3 crystal morphology were reported already in the literature. Many authors have used similar operating conditions, but using other water-soluble polymers.22 Recently, we established that the poly (acrylamide-co2-acrylamido-2-methyl-1-propane sodium sufonate-co-nvinyl pyrrolidone) has a significant effect on the overgrowth of CaCO3 crystals. The terpolymer bears hydrophilic groups designed to interact with inorganic salts and surfaces and other hydrophilic groups which just promote dissolution in water but do not interact with the dissolved ions. The terpolymer P(AM-NaAMPS-NVP) (Figure 1) contains a number of functionalities, which are known to bind strongly to metal ions. It is our contention that this ability to bind metal ions may be exploited in crystal growth assays of metal carbonates. Experimental Section Materials. Acrylamide monomer (B.D.H., U.K.) was recrystallized from chloroform and washed with benzene (B.D.H., reagent grade). Then it was dried in a vacuum to constant weight and was stored over silica gel in desiccators. 2-Acrylamido-2methyl-1-propane sulfonic acid (AMPS), A.R.-grade (Aldrich), was used as received. NaAMPS was prepared by dissolving AMPS in sodium hydroxide solution. N-Vinyl pyrrolidone (Aldrich) was used as received. Synthesis and characterization of the watersoluble terpolymer will be the subject of future work.23 Figure 1 represents the chemical structure of the synthetic water-soluble terpolymer. Calcium chloride, sodium bicarbonate, and sodium (19) Co¨lfen, H. Macromol. Rapid Commun. 2001, 22, 219-252. (20) Co¨lfen, H.; Antonietti, M. Langmuir 1998, 14, 582. (21) Sedlak, M.; Co¨lfen, H. Macromol. Chem. Phys. 2001, 202, 587597. (22) Co¨lfen, H.; Qi, L. Chem. Eur. J. 2001, 7, 106. (23) Pai, R. K.; Pillai, S.; Hild, S. in press.

Figure 2. Representative FESEM images (a, b) or SEM images (c) of the polymorphs of CaCO3 crystals grown (a) in the absence of poly-Asp and synthetic polymer, (b) in the presence of synthetic polymer without poly-Asp, and (c) in the presence of synthetic polymer and poly-Asp. azide were purchased from Merck. Water was purified by Milli-Q (Millipore). To adjust the pH, 0.1 M HCl or 0.1 M NaOH was used. Methods. (a) Preparation of Calcium Carbonates Polymorphs. The precipitation of CaCO3 on polymeric substrate was carried out in a round-bottom flask (RBF) at room temperature. About 1.6 g of polymer was transferred into a 250 mL round-bottom flask, and 50 mL of 0.1 M CaCl2 was added. The polymer was allowed to swell overnight. The solution was homogenized the next day using a magnetic stirrer and adjust to a pH of 8.5 using

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Figure 3. Representative tapping mode AFM images of (a) height data, (b) phase data (1a, 1b) synthetic water-soluble terpolymer, and (2a, 2b) synthetic water-soluble terpolymer with poly-Asp. 0.1 N NaOH. This solution was kept under N2 to prevent the dissolution of CO2 from the air. A 50 mL sample of 0.1 M Na2CO3 (pH ) 11) was added dropwise under continuous stirring. To prevent bacterial growth, 0.1 mass% sodium azide was added to the solution. After complete addition of Na2CO3, the solution was kept for 1 week at room temperature to allow for crystals growth on the polymeric substrate. The polymer solution containing the CaCO3 precipitates was filtered through a 22 µm pore size filter media and washed three times with Millipore water. Finally, the product was air-dried at room temperature. We tested the effect of poly-Asp on CaCO3 precipitation by adding 10 mg of poly-Asp to 100 mL polymer solution. In a control experiment, both the polymer and poly-Asp were omitted. (b) Atomic Force Microscopy (AFM). AFM studies on the CaCO3 crystals were carried out in air using D3100 Scanning Force Microscope equipped with a Nanoscope IIIa controller (Veeco Instruments, Santa Barbara, CA). Pictures are taken under ambient conditions (30% humidity, 278 K) in Tapping Mode TM (TM) using standard microfabricated silicon cantilever with aluminum reflex coating (Olympus, OMCL 160TS). We applied setpoint amplitude between 1.4 and 1.5 V. (c) Field Emission Scanning Electron Microscopy (FESEM). SEM studies on the CaCO3 crystals were carried out using either a Hitachi S-5200 field-emission scanning electron microscope at acceleration voltage at 15 or 20 kV after rotary coating with 2 nm of platinum at an angle of 45° in a Balzers BAF 300, or a Zeiss DSM 962 SEM at accelerating voltage of 15 kV after sputter coating with 10 nm gold/paladium in Balzers MED 010. (d) Energy Dispersive Spectroscopy (EDS). Since the experimental solutions contain NaCl, we performed EDS to analyze

the chemical composition of the crystals. The results verified that the precipitate is CaCO3 with only little/no Na and Cl present. (e) Calcium Ion Measurements. To estimate the polymer/CaCO3 ratio, we dissolved 1 aliq of sample in 0.1 M KCl adjusted to a PH of 7.0 and measured the Ca2+ concentration using Ca2+ selective mini electrodes (ETH 129). We use the calibration solutions according to Tsien and Rink24 (1980). Since ionic strength in our sample and test solutions were equal, Ca2+ concentration rather than Ca2+ activity was determined. (f) X-Ray Diffraction Studies. Powder X-ray diffraction studies on the crystals were carried out using Guinier D5005 X-ray diffractometer with Cu KR radiation at 40 kV and 30 mA system. (g) Infrared Spectroscopy (FTIR). Spectra were recorded on a Bruker FT/ IR-IFS 113V spectrometer. Samples were examined in potassium bromide disks.

Results and Discussion Scanning Electron Microscopy (SEM). For the close examination of CaCO3 crystal morphology, we performed SEM analysis. Figure 2 shows a typical SEM micrographs of CaCO3 particles. In the control experiment in which no polymer/poly-Asp were present, rhombohedral crystals characteristic of calcite were produced as shown in Figure 2a. When the water-soluble terpolymer was used as a substrate, the crystallization of CaCO3 resulted in stacked (24) Tsien, R. Y.; Rink. T. J. J. Biochim. Biophys. Acta 1980, 599, 623-638.

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Figure 4. Representative tapping mode AFM images of (a) height data, (b) phase data (1a, 1b) CaCO3 crystals grown in the presence of synthetic polymer without poly-Asp, and (2a, 2b) CaCO3 crystals grown in the presence of synthetic polymer with poly-Asp.

crystal aggregates with a mean size of 10 µm (Figure 2b). The obtained particles are rather uniform in size and shape, with (104) rhombohedral faces and this was confirmed by XRD. In combination with polymer/polyAsp, the crystallization of CaCO3 resulted in crystals that exhibited an unusual morphology, that is, a hollow needlelike or plate like morphology with rough surfaces (Figure 2c) is found. A closer examination of these elongated hollow crystals indicated that it is an array of columnar rods. The rods had a length of 5-10 µm and were highly oriented parallel to each other. XRD pattern of the collected crystals confirmed the lattice structure of both phases. Atomic Force Microscopy (AFM). AFM is capable of nanometer resolution on crystal surfaces32,33 and excels (25) Manoli, F.; Dalas, E. J. Cryst. Growth 1999, 240, 369-375. (26) Manoli, F.; Koutsopoulos, S.; Dalar, E. J. Cryst. Growth 1997, 182, 116-124. (27) Selegny, E., Ed. In Polyelectrolyte; Reidel: Boston, 1974. (28) Milos, S.; Markus, A.; Co¨lfen, H. Macromol. Chem. Phys. 1998, 199, 247-254. (29) Ueyama, N.; Hosoi, T.; Yamada, Y.; Doi, M.; Okamura, T.; Nakamura, A. Macromolecules 1998, 31, 7119-7126. (30) Gutjahr, A.; Dabringhaus, H.; Lacmann, R. J. Cryst. Growth 1996, 158, 296-309. (31) Nassrallah-Aboukais, N.; Boughriet, A.; Laureyns, J.; Aboukais, A.; Fischer, J. C.; Langelin, H. R.; Wartel, M. Chem. Mater. 1998, 10, 238-243. (32) Quate, C. F. Surf. Sci. 1994, 299-300; 980-995.

at imaging a wide variety of biomolecules.34 AFM can also image under liquids, enabling process of crystal growth to be studied in situ.35 We therefore have used AFM to examine the effects of polymer/ poly-Asp on a growing crystal surface in situ. Figure 3 (1a,1b) shows the typical tapping mode AFM images of terpolymer surface. Here the surface is smooth ≈ 15 nm with layered structure indicating some phase separation. Entrapment of polyAsp in the terpolymer, Figure 3 (2a,2b), has enable us to visualize in situ the interaction of poly-Asp on terpolymer, resulting in a spongelike structure with surface roughness ≈ 300 nm. Figure 3 (2a,2b) and Figure 4 (1a,1b,2a,2b) are at higher magnifications; however, the AFM revealed the adsorbates, which are not visible otherwise. These images make possible direct, visual observation of molecules that are absorbed on crystal surfaces. The adsorbates are tightly bound on a surface that is stable enough so that the AFM probe does not displace the molecules of either the adsorbates.36,37 (33) Wiesendanger, R. Cambridge University Press: Cambridge, 1994. (34) Shao, Z.; Mou, J.; Czajkowsky, D. M.; Yang, J.; Yuan, J. Y. Adv. Phys. 1996, 45, 1-86. (35) Bosbach, D.; Jordan, G.; Rammensee, W. Eur. J. Mineral. 1995, 7, 267-276. (36) Zasadzinski, J. A.; Viswanathan, R.; Madsen, L.; Garnaes, J.; Schwartz, D. K. Science 1994, 263, 1726-1733. (37) Drake, B., Hellmann, R., Sikes, C. S., and Occelli, M. L. SPIE 1992, 1639, 151-159.

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Figure 5. FTIR spectra recorded from the water-soluble terpolymer (curve a), the CaCO3 crystals grown in the presence of polymer without poly-Asp (curve b), the CaCO3 crystals grown in the presence of polymer with poly-Asp (curve c), and the CaCO3 crystals grown in the absence of polymer and poly-Asp (curve d).

X-Ray Diffraction (XRD). X-Ray diffraction of our crystal aggregates showed strong diffraction maxima at 2θ ≈ 30° that correspond to the {104}-faces of the rhombohedral crystallites and at 2θ ≈ 32.8° that correspond to aragonite crystals. Infrared Spectroscopy (FTIR). Figure 5 shows the FTIR spectra recorded from the water-soluble terpolymer (curve a), the CaCO3 crystals grown in the presence of polymer without poly-Asp (curve b), the CaCO3 crystals grown in the presence of polymer with poly-Asp (curve c), and the CaCO3 crystals grown in the absence of polymer and poly-Asp (curve d). Prominent absorption bands are seen at 1377, 1460, 1545, 1633, 1663, 2855, 2922, and 3429 cm-1 (Figure 5a) in the case of the terpolymer sample. The band at 1377 cm-1 is assigned to the S)O stretching vibration of the sulfonate group present in the terpolymer. The band at 1545, 1633, and 1663 cm-1 is due to carbonyl stretch vibrations of AMPS, NVP, and AM, respectively. Amide unit of the terpolymer comes at 3429 cm-1. Methyl group of AMPS unit comes at 1460 cm-1, and the two bands at 2855 and 2922 cm-1 have been assigned to the methylene symmetric and antisymmetric stretching vibrations, respectively, in the hydrocarbon chains (Figure 5a). The methylene antisymmetric and symmetric vibrations have reduced marginally in intensity following Ca2+ incorporation, and we can see that strong infrared absorption bands at 713 and 877, which is the characteristic of the calcite polymorph (Figure 5b). The almost complete disappearance of the methylene antisymmetric and symmetric vibration bands after aragonite formation (Figure 5c) indicates considerable reorganization in the terpolymer chemical structure, possibly due to the randomization of bioorganic macromolecular chain orientation around the aragonite crystals. After entrapment of poly-L-aspartic acid in the polymer, the absorption band at 1377 cm-1

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shifted to 1195 cm-1 (Figure 5c), clearly indicating that the protein have complexes with the sufonate group of the terpolymer. Also, the presence of absorption bands at 2512 and 2927 cm-1 of the carboxyl group and band at 1685 cm-1 of the amide group indicates the presence of poly-Asp in the polymeric substrate. The strong infrared absorption bands at 850 cm-1 is the characteristic of the aragonite polymorph. A small absorption band at 877 cm-1 characteristic to the calcite polymorph indicates that there is some transformation of aragonite into the calcite modification. Effects of Polymer/Poly-Asp. In the control experiment, crystals of calcium carbonate were rhombohedrons (Figure 2a) where crystals grown in the presence of polymeric substrate/additive had altered morphology (Figure 2b,c, Figure 4). Manoli et al.25,26 have shown that elastin and chitin substrates enhance the nucleation of calcite crystals due to the presence of >C)O and >S)O functional groups at the substrate. Our polymer contain >NH, >C)O, and >S)O functional groups at the surface and are expected to interact with calcium ions. When the crystal growth experiment were performed in the presence of terpolymer without poly-Asp, a remarkable increase in nucleation density (number of crystals per unit area) was observed with stacked crystals of rhombohedral morphology. This may be due to the expansion of polymeric chains by the contribution of pendent -SO3 Na groups. When the terpolymer dissolves in CaCl2 solution, the ionizabale groups dissociate, resulting in macromolecules bearing electrostatic charges and mobile counterions. The strong electrostatic interaction of the charges on the macroion results in their greatly expanded conformation.27 The calcite crystals grow along the expanded polymeric chain without any preferred orientation. Each repeating unit of the polymeric structure has >NH, >C)O, and >S)O groups which act as nucleation sites and accelerate the growth of the crystallites. This was evident from the fact that the stacked crystals of rhombohedral morphology were formed on the polymer surface. The crystals grown in the presence of terpolymer with poly-Asp had the typical morphology of needlelike or plate like aragonite (Figure 2c and Figure 4, panels 2a and 2b). The generation of more nucleation sites in the poly-Asp may be responsible for the selective nucleation of aragonite crystals. Helmut Co¨lfen et al.28 showed that the crystallization inhibition efficiency of the double hydrophilic block copolymer is about 3-4 times higher, due to the incorporation of poly-Asp. We have not yet systematically studied the kinetics as a function of polymer/poly-Asp concentration and pH; however, under specific experimental conditions, we have observed the growth of hollow crystals of aragonite. The stabilization of hollow crystals of aragonite on terpolymer in the presence of polyL-aspartic acid could be due to the change in the chemical environment at the terpolymer surface. This is supported by AFM results. It is known that formation of the stabilized crystal phase requires strong Ca-O interaction with the substrate surface29 or additives. Poly-Asp molecules become part of the crystal lattice in the sense that anionic carbonyl groups of aspartate residues substitute for carbonate ions of the lattice. This enhances the binding energy between the polymer/poly-Asp and the crystal surface. Poly-Asps have very strong binding energies when stereochemically bound to aragonite, particularly if they become incorporated into the crystal lattice. This was confirmed by FTIR (Figure 5c). It is likely that the presence of poly- L-aspartic acid increases the number of polar functional groups, which are known to interact strongly with polar groups of the terpolymer forming a complex

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organic matrix. This may result in the selective nucleation of hollow crystals of aragonite. Another explanation for the growth of these hollow plates such as aragonite crystals can be the initial formation of an unstable CaCO3 modification, such as amorphous CaCO3. With time, amorphous CaCO3 will be transformed to the more stable modifications, especially in the presence of moisture. Gutjahr, A et al.30 explained this transformation clearly by the Ostwald step rule. Under standard conditions, the vaterite phase readily transforms into the stable aragonite or calcite phase in the presence of water through a solventmediated mechanism.31 This process involves dissolution of vaterite crystals followed by nucleation of the calcite phase and generally takes place within 80 h. Such transformation could probably be supressed by the combined effect of terpolymer/poly-Asp. During the structural transformation form vaterite to aragonite, may leads to a hollow crystals.

bioorganic macromolecules, stacked crystals of rhombohedral morphology were deposited on the expanded polymeric chain. However, in the presence of bioorganic macromolecules, almost all crystals are hollow and have a plate-like morphology that were deposited within a complex organic matrix. The water-soluble terpolymers reported here allow us to increase the nucleation density (number of crystals per unit area) using specific experimental conditions, and the presence of soluble polyL-aspartic acid molecules allows us to induce the crystallization of individual CaCO3 polymorphs with preferred morphologies. In this study, we only wanted to demonstrate the effectivity of this new class of water-soluble terpolymer for CaCO3 stabilization. In future work, we will focus systematic studies on the mechanism and kinetics as a function of terpolymer/poly-Asp concentration and pH for CaCO3 stabilization.

Conclusion

Acknowledgment. This work is financially supported by the Graduate College “Molecular Organization and Dynamics at Interfaces” fund (to R.K.P.) and Deutsche Forschungsgemeinschaft Grant Zi368/4-2 (to A.Z. and S.H.) within the research program “Principles of Biomineralization” (SSP 1117). We thank Dr. Bernd Heise, Abt. Experimentelle Physik, for X-ray analysis and Elvira Kaltenecker, Inorganic Chemistry II, for FTIR analysis.

The determination of the structural relationship between polymer and mineral growth is important for understanding of adherence of the inorganic particles to the organic substrates. In the present work, we have shown that the presence of a large number of functionalities on terpolymer suspended in stable, aqueous supersaturated solutions results in overgrowth by calcium carbonate crystals. It is of particular interest that in the absence of

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