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Template-assisted preparation of chainlike CaCO3
Materials Letters 60 (2006) 1366 – 1368 www.elsevier.com/locate/matlet
Template-assisted preparation of chainlike CaCO3 Ye Sheng, Bing Zhou, Xu Zhao, Chengyu Wang, Ying Liu, Zichen Wang ⁎ Institute of Chemistry, Jilin University, 130021 Changchun, China Received 5 July 2005; accepted 10 November 2005 Available online 1 December 2005
Abstract The chainlike CaCO3 was prepared by carbonating route in the presence of polyethylene glycol (PEG). In addition, we found the larger the molecular weight of PEG, the longer the CaCO3 chain was. All the facts are attributed to the template effect of PEG, which control the nucleation, growth, and alignment of CaCO3 particles. XRD data showed that the obtained products were all calcite. © 2005 Elsevier B.V. All rights reserved. Keywords: Template; PEG; Chain CaCO3
1. Introduction A large number of organisms are capable of exerting remarkable control over the fabrication of biominerals by using interactions between inorganic substances and biomacromolecules [1–3]. Athough the processes of biomineralization are not fully understood, approaches to mimicking these processes may result in the fabrication of new organic/inorganic hybrid materials [4]. The strategy of using organic additives and/or templates to control the nucleation, growth, and alignment of inorganic particles has been universally applied for the controllable synthesis of various inorganic materials with unusual and complex forms [5,6]. The controllable synthesis of calcium carbonate (CaCO3) has received much attention owing to its wide application in such industrial fields as paper, rubber, plastic, paint, etc. [7]. The application of CaCO3 particles is determined by a number of strictly defined parameters, such as morphology, structure, size, specific surface area, brightness, oil adsorption, chemical purity, and so on. One of the most important parameters is particle morphology. CaCO3 particles in chain shape are desirable in such industries as rubber, plastics etc., where strengthening is very important.
⁎ Corresponding author. Tel./fax: +86 431 8499134. E-mail address: [email protected] (Z. Wang). 0167-577X/$ - see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2005.11.030
In our work, we found that polyethylene glycol (PEG), as a template, could induce the formation of calcium carbonate chain by carbonating route, furthermore, the larger the molecular weight of PEG is, the longer the chain is. 2. Experimental 2.1. Materials All reagents were used without further purification. PEG with different molecular weight were purchased from the Beijing Chemical Co. of China. According to their molecular weight, we denote them as PEG400, PEG2000, PEG6000 and PEG10000, respectively. Calcium oxide (CaO) was of reagent grade, and water is distilled water. 2.2. Instrumentation The size and morphology of particles was characterised by transmission election microscope (TEM), which was carried out using a Hitach 8100IV at 100 kv. The powder structure and phase transformation of the composites were characterized by X-ray diffractometry (XRD Rigaku, employing CuKα radiation). The fraction of the chemisorbed water or organic of the samples is determined by thermogravimetry analysis (TGA) using a SHIMADZU TGA-60 H, which were performed in a flowing air atmosphere, and the samples heated at a rate of 20 °C/min.
Y. Sheng et al. / Materials Letters 60 (2006) 1366–1368
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Fig. 1. TEM of obtained product: (a) without PEG (b) with PEG400 (c) with PEG2000 (d) with PEG6000 (e) with PEG10000.
Calcium oxide (CaO) was digested in distilled water with 2% or without PEG to form calcium hydroxide slurry of a certain concentration and for overnight. Before transferred into a bubble column the slurry was filtered through a 150-mesh sieve. The inside diameter (i.d.) of the column was 5 cm and a gas inlet tube which i.d. was 0.8 cm was
put just above the bottom of the column. Carbon dioxide (CO2) and Nitrogen (N2) were mixed with a molar ration 3 : 10 first, then through the tube the mixture was introduced into the slurry. The introduction was stopped when the pH value turned to 7, white precipitates were obtained by filtration. The obtained precipitates were washed with distilled water for three times and oven dried to 80 °C for 24 h.
Fig. 2. The XRD patterns of the product (2% PEG10000).
Fig. 3. TG curve of (a) sample A ( without PEG) and (b) sample E (chain CaCO3 prepared by the carbonating route in the presence of PEG 10,000).
2.3. Preparation of chainlike calcium carbonate
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Y. Sheng et al. / Materials Letters 60 (2006) 1366–1368
3. Results and discussion TEM analyses provided visual evidence of the morphology, size and structure of the particles. Detailed TEM observation showed that usually CaCO3 formed by the carbonating route was cubic (Fig. 1a), while the morphology of the product changed gradually in the presence of PEG. When PEG400 was added, the morphology of the product changed little (Fig. 1b), but when the PEG was PEG2000 and PEG6000, the cubic CaCO3 has been self-assembled into chainlike CaCO3 at the template of PEG (Fig. 1c and d) and when the PEG10000 was added, the obvious chainlike CaCO3 was formed (Fig. 1e). In addition, the chain consisted of small cubic CaCO3 particles jointed together. All the facts showed that PEG really played an important role of template action in the formation of CaCO3 chain, which is perhaps relative to its amounts of hydroxyl groups and molecular structure. As we know, PEG was used to enhance the homogeneity of the metal cations. Since PEG has ether oxygens in its chain, it can interact with metal ions [8]. The interaction and random arrangement of the polymer chain make the metal cations mixed at the molecular level. However, the detailed mechanism is waiting to be investigated further. The phase purity of the samples was evaluated by using a Rigaku X-ray diffractometer with monochromatized Cu Kα radiation (λ = 1.5418 Å). Fig. 2 shows the representative XRD pattern of the as-synthesized CaCO3 chain at the presence of PEG10000. It is clear that all the reflections can be readily indexed to a pure calcite phase of CaCO3 conforming to a space group of R 3 c (167) (JCPDS 851108). No impurity peaks were detected, indicating that the powders had high purity. The TGA analysis for the crystalline CaCO3 obtained in the presence of PEG10000 gave a larger 1∼2% weight loss at 220∼700 °C than that of the pure CaCO3 (Fig. 3), which was due to the decomposition of the organic moieties of the PEG10000. IR spectral analysis of obtained product was shown in Fig. 4. In trace b, absorption occurred around 2921 cm− 1, 2852 cm− 1 which is the characteristic of H–C–H asymmetric and symmetric stretching vibration, respectively, furthermore, the ∼3420 cm− 1 absorption should be attributed to the stretching vibration of –OH.
4. Conclusions We succeeded in preparing the chainlike CaCO3 by carbonating route in the presence of polyethylene glycol (PEG). XRD
Fig. 4. IR spectra of (a) the blank one (b) 2% PEG10000 was added at digestion time.
data showed that the obtained products were all calcite. TGA analysis and IR showed that there was organic PEG in the sample. In addition, we found the larger the molecular weight of PEG, the longer the CaCO3 chain was. All the facts are attributed to the template effect of PEG, which control the nucleation, growth, and alignment of CaCO3 particles. Acknowledgements The authors of this paper would like to thank Jilin University for financial support of this research. References [1] [2] [3] [4] [5] [6] [7] [8]
S. Mann, Nature 332 (1988) 119. L. Addadi, S. Weiner, Angew. Chem., Int. Ed. Engl. 31 (1992) 153. G. Krampitz, G. Graser, Angew. Chem., Int. Ed. Engl. 27 (1988) 1145. T. Kato, A. Sugawara, N. Hosoda, Adv. Mater. 14 (2002) 869. G. Falini, S. Albeck, S. Weiner, L. Addadi, Science 271 (1996) 67. D.B. DeOliveira, R.A. Laursen, J. Am. Chem. Soc. 119 (1997) 10627. E. Dalas, P. Klepetsanis, P.G. Koutsoukos, Langmuir 15 (1999) 8322. T. Okada, Analyst 118 (1993) 959.
Template-assisted preparation of chainlike CaCO3 Ye Sheng, Bing Zhou, Xu Zhao, Chengyu Wang, Ying Liu, Zichen Wang ⁎ Institute of Chemistry, Jilin University, 130021 Changchun, China Received 5 July 2005; accepted 10 November 2005 Available online 1 December 2005
Abstract The chainlike CaCO3 was prepared by carbonating route in the presence of polyethylene glycol (PEG). In addition, we found the larger the molecular weight of PEG, the longer the CaCO3 chain was. All the facts are attributed to the template effect of PEG, which control the nucleation, growth, and alignment of CaCO3 particles. XRD data showed that the obtained products were all calcite. © 2005 Elsevier B.V. All rights reserved. Keywords: Template; PEG; Chain CaCO3
1. Introduction A large number of organisms are capable of exerting remarkable control over the fabrication of biominerals by using interactions between inorganic substances and biomacromolecules [1–3]. Athough the processes of biomineralization are not fully understood, approaches to mimicking these processes may result in the fabrication of new organic/inorganic hybrid materials [4]. The strategy of using organic additives and/or templates to control the nucleation, growth, and alignment of inorganic particles has been universally applied for the controllable synthesis of various inorganic materials with unusual and complex forms [5,6]. The controllable synthesis of calcium carbonate (CaCO3) has received much attention owing to its wide application in such industrial fields as paper, rubber, plastic, paint, etc. [7]. The application of CaCO3 particles is determined by a number of strictly defined parameters, such as morphology, structure, size, specific surface area, brightness, oil adsorption, chemical purity, and so on. One of the most important parameters is particle morphology. CaCO3 particles in chain shape are desirable in such industries as rubber, plastics etc., where strengthening is very important.
⁎ Corresponding author. Tel./fax: +86 431 8499134. E-mail address: [email protected] (Z. Wang). 0167-577X/$ - see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2005.11.030
In our work, we found that polyethylene glycol (PEG), as a template, could induce the formation of calcium carbonate chain by carbonating route, furthermore, the larger the molecular weight of PEG is, the longer the chain is. 2. Experimental 2.1. Materials All reagents were used without further purification. PEG with different molecular weight were purchased from the Beijing Chemical Co. of China. According to their molecular weight, we denote them as PEG400, PEG2000, PEG6000 and PEG10000, respectively. Calcium oxide (CaO) was of reagent grade, and water is distilled water. 2.2. Instrumentation The size and morphology of particles was characterised by transmission election microscope (TEM), which was carried out using a Hitach 8100IV at 100 kv. The powder structure and phase transformation of the composites were characterized by X-ray diffractometry (XRD Rigaku, employing CuKα radiation). The fraction of the chemisorbed water or organic of the samples is determined by thermogravimetry analysis (TGA) using a SHIMADZU TGA-60 H, which were performed in a flowing air atmosphere, and the samples heated at a rate of 20 °C/min.
Y. Sheng et al. / Materials Letters 60 (2006) 1366–1368
1367
Fig. 1. TEM of obtained product: (a) without PEG (b) with PEG400 (c) with PEG2000 (d) with PEG6000 (e) with PEG10000.
Calcium oxide (CaO) was digested in distilled water with 2% or without PEG to form calcium hydroxide slurry of a certain concentration and for overnight. Before transferred into a bubble column the slurry was filtered through a 150-mesh sieve. The inside diameter (i.d.) of the column was 5 cm and a gas inlet tube which i.d. was 0.8 cm was
put just above the bottom of the column. Carbon dioxide (CO2) and Nitrogen (N2) were mixed with a molar ration 3 : 10 first, then through the tube the mixture was introduced into the slurry. The introduction was stopped when the pH value turned to 7, white precipitates were obtained by filtration. The obtained precipitates were washed with distilled water for three times and oven dried to 80 °C for 24 h.
Fig. 2. The XRD patterns of the product (2% PEG10000).
Fig. 3. TG curve of (a) sample A ( without PEG) and (b) sample E (chain CaCO3 prepared by the carbonating route in the presence of PEG 10,000).
2.3. Preparation of chainlike calcium carbonate
1368
Y. Sheng et al. / Materials Letters 60 (2006) 1366–1368
3. Results and discussion TEM analyses provided visual evidence of the morphology, size and structure of the particles. Detailed TEM observation showed that usually CaCO3 formed by the carbonating route was cubic (Fig. 1a), while the morphology of the product changed gradually in the presence of PEG. When PEG400 was added, the morphology of the product changed little (Fig. 1b), but when the PEG was PEG2000 and PEG6000, the cubic CaCO3 has been self-assembled into chainlike CaCO3 at the template of PEG (Fig. 1c and d) and when the PEG10000 was added, the obvious chainlike CaCO3 was formed (Fig. 1e). In addition, the chain consisted of small cubic CaCO3 particles jointed together. All the facts showed that PEG really played an important role of template action in the formation of CaCO3 chain, which is perhaps relative to its amounts of hydroxyl groups and molecular structure. As we know, PEG was used to enhance the homogeneity of the metal cations. Since PEG has ether oxygens in its chain, it can interact with metal ions [8]. The interaction and random arrangement of the polymer chain make the metal cations mixed at the molecular level. However, the detailed mechanism is waiting to be investigated further. The phase purity of the samples was evaluated by using a Rigaku X-ray diffractometer with monochromatized Cu Kα radiation (λ = 1.5418 Å). Fig. 2 shows the representative XRD pattern of the as-synthesized CaCO3 chain at the presence of PEG10000. It is clear that all the reflections can be readily indexed to a pure calcite phase of CaCO3 conforming to a space group of R 3 c (167) (JCPDS 851108). No impurity peaks were detected, indicating that the powders had high purity. The TGA analysis for the crystalline CaCO3 obtained in the presence of PEG10000 gave a larger 1∼2% weight loss at 220∼700 °C than that of the pure CaCO3 (Fig. 3), which was due to the decomposition of the organic moieties of the PEG10000. IR spectral analysis of obtained product was shown in Fig. 4. In trace b, absorption occurred around 2921 cm− 1, 2852 cm− 1 which is the characteristic of H–C–H asymmetric and symmetric stretching vibration, respectively, furthermore, the ∼3420 cm− 1 absorption should be attributed to the stretching vibration of –OH.
4. Conclusions We succeeded in preparing the chainlike CaCO3 by carbonating route in the presence of polyethylene glycol (PEG). XRD
Fig. 4. IR spectra of (a) the blank one (b) 2% PEG10000 was added at digestion time.
data showed that the obtained products were all calcite. TGA analysis and IR showed that there was organic PEG in the sample. In addition, we found the larger the molecular weight of PEG, the longer the CaCO3 chain was. All the facts are attributed to the template effect of PEG, which control the nucleation, growth, and alignment of CaCO3 particles. Acknowledgements The authors of this paper would like to thank Jilin University for financial support of this research. References [1] [2] [3] [4] [5] [6] [7] [8]
S. Mann, Nature 332 (1988) 119. L. Addadi, S. Weiner, Angew. Chem., Int. Ed. Engl. 31 (1992) 153. G. Krampitz, G. Graser, Angew. Chem., Int. Ed. Engl. 27 (1988) 1145. T. Kato, A. Sugawara, N. Hosoda, Adv. Mater. 14 (2002) 869. G. Falini, S. Albeck, S. Weiner, L. Addadi, Science 271 (1996) 67. D.B. DeOliveira, R.A. Laursen, J. Am. Chem. Soc. 119 (1997) 10627. E. Dalas, P. Klepetsanis, P.G. Koutsoukos, Langmuir 15 (1999) 8322. T. Okada, Analyst 118 (1993) 959.