- Email: [email protected]
SiO2 hybrid materials
Materials Letters 61 (2007) 1292 – 1295 www.elsevier.com/locate/matlet
Synthesis and properties of chitosan/SiO2 hybrid materials Jen-Taut Yeh a,b , Chin-Lai Chen a , Kuo-Shien Huang c,⁎ a
Graduate School of Polymer Engineering, National Taiwan University of Technology, Taipei, Taiwan b Department of Textile Engineering, Nanya Institute of Technology, Jiung Li, Taiwan c Department of Polymer Materials, Kun Shan University, Yung Kang, Tainan, 71003, Taiwan Received 8 April 2006; accepted 6 July 2006 Available online 28 July 2006
Abstract This study primarily aims to explore the strength and thermal properties of various hybrid materials that are made of tetraethoxysilane/ vinyltriethoxysilane (TEOS/VTES) and chitosan in different weight ratios. It is confirmed, from micro Fourier transform infrared (micro FT-IR) and nuclear magnetic resonance (NMR) analysis, that hydrogen bonds emerge between chitosan and SiO2 in hybrid materials. With the addition of more VTES and TEOS, the surface of the hybrid material features thick granules. In addition, the mechanical performance and thermostability of both types of hybrid are better than pure chitosan. The former is enhanced with an increasing amount of TEOS until it exceeds 2.4 g and the latter is also improved with an increasing amount of TEOS. © 2006 Elsevier B.V. All rights reserved. Keywords: Strength; FT-IR; NMR; Thermal properties
1. Introduction Chitosan, which is deacetylated chitin, is low in cost, has a stable performance, and belongs to an innocuous, biolytic and active amino group [1]. It is widely used in the fields of waste water treatment, food production, textiles, agriculture and biological medicine [2–4], and even in optical equipment [5]. However, the poor water solubility of chitosan narrows its application and results in inconvenient fabrication; many researchers are therefore working on the production of water-soluble chitosan [6–8]. The unsound strength and physical properties of chitosan also deny its use in certain fields [9–12]. A convenient and effective solution to these drawbacks is to produce chitosan, as many researchers have, interlinked with glutaraldehyde [13], polyalcohol [14], polybasic carboxylic acid [15], epoxide [16] and deformed starch [17]. These, however, may all trigger toxicity problems, so natural interlinkage agents such as genipin or quinine [18–20] are more preferable. Chitosan, which is similar to cellulose in chemical constitution except for an amino group on the second carbon, can readily work with inorganic material
⁎ Corresponding author. E-mail address: [email protected] (K.-S. Huang). 0167-577X/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2006.07.016
through a sol–gel method to form hybrid materials with hydrogen bonds [21]. An effective way of synthesizing nano-hybrid materials with TEOS and organic molecules is through a sol–gel process. Such hybrid materials, which are improved in terms of the physical and chemical performances of high molecular material, have both rigid and rugged inorganic material and their organic material is multifunctional [22–24]. This study therefore proposes to synthesize hybrid materials with TEOS/VTES in different weight ratios mixed with chitosan through a sol–gel process and tests the relevant physical and chemical properties. 2. Experimental 2.1. Materials All the following are of reagent grade: chitosan (85% deacetylation; Taiwan Kaohsiung Applied Chemistry Co. Ltd), isopropanol (IPA), ammonium persulfate (the above two agents were purchased from Panreac Quimicasa, made in E.U.), glycerin, formic acid (Pharmaceutical Chemistry Corporation, Japan), tetraethoxysilane (TEOS, ACROS, USA) and vinyltriethoxysilane (VTES, ACROS, USA). The non-ion surfactant (NP-50; Taiwan Central Asia Xingye Co. Ltd) is of industrial grade.
J.-T. Yeh et al. / Materials Letters 61 (2007) 1292–1295
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surface. Tensile strength and elongation properties were performed on a universal testing machine (Alphaten 400 Tester, Gau Te Machine Co. Ltd, Taiwan). The samples free from air bubbles were cut into a dumbbell shape type IV (ASTM D638). The samples were performed at 25 mm gage length with the speed of 50 mm/min and 1 kN load cell. The thermal properties of samples were measured by DuPont 2200 weight-loss analyzer (U.S.A.). The 5–10 mg samples were placed in alumina crucibles and test with a thermal ramp over a temperature range of 30–600 °C, at a heating rate of 20 °C/min under nitrogen flow speed of 20 cm3/min, after which their initial decomposition temperature (IDT) was obtained. 3. Results and discussion 3.1. FT-IR
Fig. 1. FT-IR of chitosan and hybrid materials. ((a): Chitosan, (b): VTES, (c): chitosan/VTES, (d): chitosan/TEOS, (e): chitosan/VTES–TEOS).
2.2. Methods Standard A: Formic acid was added to 4 g chitosan until the mixture reached 100 g in total. Adequate VTES, 1 g non-ion surfactant, 2 g ammonium persulfate and 200 ml distilled water were added so that the reagent in the mixture dissolved, and then perfused with nitrogen gas and reacted at 40 °C for 3 h. Standard B: 0–3.2 g TEOS and 30 ml IPAwere prepared and added to 70 ml water; the pH of the solution was regulated to about 2–3 with 0.05 M HCl and stirred for 0.5 h at room temperature. Standard B was decanted to Standard A and reacted for 2 h at 40 °C to produce gel. The constant weight gel-like product was then poured into a glass mold to obtain a sample film (1 mm) with 10 × 20 cm2 and kept at 50 °C for 2 days. The films were neutralized in a 0.5 M NaOH solution and dried at 50 °C for another 2 days under reduced pressure.
Fig. 1 shows the Fourier transform infrared (FT-IR) results of the hybrid materials. Fig. 1a shows that, due to 85% deacetylation and parts of the chitin, an absorption peak exists of N C_O and CONH at 1631 cm− 1 and 1547 cm− 1. The absorption peak of C–OH is found at 1066 cm− 1 and 1030 cm− 1 and that of C–O–C at 1150 cm− 1, indicating the presence of chitosan. Fig. 1b shows the FT-IR results of VTES. The absorption peak of the ethylene group is found at 1601 cm− 1, 961 cm− 1 and 762 cm− 1 and Si–O–C at 1048 cm− 1. It is evident in Fig. 1c and e — that the absorption peak disappeared at 961 cm− 1 and 762 cm− 1, which reveals a combined polymerization of VTES and chitosan. Fig. 1c, d and e also show absorption peaks of Si–O–Si or C–OH in the hybrid materials. The absorption scope of these two groups overlapped and it was hard to distinguish that of each group; it was therefore necessary to perform NMR analysis for further confirmation of these results. 3.2. NMR Fig. 2 shows 13C NMR analysis for chitosan and various hybrid materials. It was found that chitosan has a C_O group absorption peak
2.3. Analysis and measurement FT-IR/ATR spectra of the samples were recorded with a BioRad Digilab FTS-200 spectrometer (U.S.A.) using an MCT detector. A diamond crystal was used as internal reflectance element. Single beam spectra were the result of 64 scans. The spectral resolution was 4 cm− 1. The chemical shifts of the 13C of powdered samples were measured with a solid-state nuclear magnetic resonance (NMR) spectrometer. The samples were analyzed using a Bruker Avance 400 13C NMR spectrometer (Germany) at 50 MHz, and the spectra were observed under cross-polarization, magic angle sample spinning and power decoupling conditions with a 90° pulse and 4 s cycle time. The surface morphologies of the films were observed with a JEOL Model JSM 6400 scanning electron microscopic (Japan). A gold coating was deposited on the samples to avoid charging the
Fig. 2. 13C NMR of chitosan and hybrid materials. ((a): Chitosan, (b): chitosan/ TEOS, (c): chitosan/VTES, (d): chitosan/VTES–TEOS).
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Fig. 3. SEM of chitosan and hybrid materials. ((a) VTES/TEOS = 0/0.8 g, (b) VTES/TEOS = 0.8/0.8 g, (c) VTES/TEOS = 1.2/0 g).
at 171.4 ppm, as a result of the 85% deacetylation of chitosan and the small amount of chitin contained. Fig. 2b, c and d show the hybrid materials that are made of chitosan/TEOS, chitosan/VTES and chitosan/ VTES–TEOS, in which the C_O group absorption peak was found at 174.7, 174.8 and 174.2 ppm, respectively, shifting towards highfrequency areas. This was verified by the remaining C_O of chitosan and SiO2 that was developed from TEOS or VTES reactions and production of hydrogen bonds. The phenoma were similar as other reported studies in the literature [25,26]. 3.3. SEM Fig. 3 reveals the scanning electron microscopy (SEM) results of the hybrid materials. Fig. 3a and c shows apparent dendritic surface structures in the hybrid materials that are made of chitosan/TEOS and chitosan/ VTES, whereas Fig. 3b shows a fine-grained appearance. Therefore it is evident that the hybrid materials that are made of TEOS or VTES and that have chitosan features have an acerose surface with interspaces for less inorganic SiO2. Crystalloids are formed, and the addition of VTES and TEOS results in an increase of inorganic elements. Firm and imporous surfaces are found in the material, as noted in Fig. 3b. In addition, the surface structure of the hybrid materials that are made from the combined polymerization reaction, hydrolysis and compounding of VTES and chitosan is not clear. 3.4. Mechanical properties The mechanical properties of the hybrid materials are shown in Table 1. The tensile strength and elongation of the hybrid materials are better than those of pure chitosan and increase as the addition of VTES and TEOS is increased. When up to 0.8/2.4 g VTES and TEOS was added, respectively, all the three properties above deteriorate, which
indicates that SiO2 can harden and toughen chitosan. In addition to the content of SiO2 rising, the hydrogen bonds inside the hybrid material molecules grow and enhance the mechanical performance, whereas excessive SiO2 may result in a lower incidence of film formation and may damage the mechanical performance. 3.5. Thermal properties The thermal properties of the hybrid materials are shown in Table 1, which indicates that the hybrid materials all possess better thermostability and thermal decomposition. They improve with an increase in the amount of VTES and TEOS as reticular inorganic SiO2 is formed. The hybrid material that was made of TEOS was higher in thermostability than that of VTES because for SiO2 to take shape is hard in the poorly soluble VTES.
Table 1 Thermal and mechanic properties of chitosan and hybrid materials Weight of VTES/ TEOS (g) 0/0 c 0/0.8 0.8/0.8 0.8/1.6 0.8/2.4 0.8/3.2 1.2/0 a b c
Thermal properties a
b
Mechanic properties
Td (°C)
Tm (°C)
Char yield (%)
Tensile strength (MPa)
Elongation (%)
245 249 253 257 260 263 247
303 306 308 310 313 315 304
34.1 37.2 40.4 43.8 45.6 47.1 36.3
32.03 33.19 36.65 38.41 31.16 30.25 33.23
19.3 20.1 21.7 22.6 18.5 17.7 19.8
Temperature at 10% weight loss. Temperature at maximum weight loss. Chitosan.
J.-T. Yeh et al. / Materials Letters 61 (2007) 1292–1295
4. Conclusions This experiment, starting from synthesizing various hybrid materials with chitosan/VTES–TEOS in different ratios via a sol– gel process, explores their physical and chemical properties. The following conclusions are made from the experimental results: 1) FT-IR and NMR analyses reveal that hydrogen bonds are actually formed between chitosan and SiO2. 2) The surface structure changes with the addition of VTES and TEOS. 3) The thermostability and mechanical performances of the hybrid materials are better than pure chitosan and improve with the amount of TEOS added. However, the mechanical performance deteriorates in the case of excessive TEOS.
[8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20]
References [21] [1] Khaled F. El-tahlawy, Magda A. El-bendary, Adel G. Elhendawy, Samuel M. Hudson, Carbohydr. Polym. 60 (2005) 421. [2] A.S. Aly, B.D. Jeon, Y.H. Park, J. Appl. Polym. Sci. 65 (1997) 1939. [3] M.E.I. Badawy, E.I. Rabea, T.M. Rogge, C.V. Stevens, G. Smagghe, W. Steurbaut, M. Hofte, Biomacromolecules 5 (2004) 589. [4] G. Skjak-Braek, T. Anthonsen, Elsevier Applied Science, London, 1989. [5] S. Lu, X. Song, D. Cao, Y. Chen, K. Yao, J. Appl. Polym. Sci. 91 (2004) 3497. [6] H. Sashiwa, N. Yamamori, Y. Ichinose, J. Sunamoto, S. Aibe, Macromol. Biosci. 3 (2003) 231. [7] S. Hirano, Y. Yamaguchi, M. Kamiya, Macromol. Biosci. 3 (2003) 629.
[22] [23] [24] [25] [26]
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Y. Zhou, Y. Yang, D. Wang, X. Liu, Chem. Lett. 32 (2003) 682. S.J.K. Francis, H.W.T. Matthew, Biomaterials 21 (2002) 2589. X. Zeng, E. Ruckenstein, J. Membr. Sci. 148 (1998) 195. Qing Yang, Fengdong Dou, Borun Liang, Qing Shen, Carbohydr. Polym. 59 (2005) 205. Atsushi Matsuda, Toshiyuki Ikoma, Hisatoshi Kobayashi, Junzo Tanaka, Mater. Sci. Eng. 24 (2004) 723. G. Goissis, E.M. Junior, R.A.C. Marcantonio, R.C.C. Lai, D.C.J. Cancian, W.M. De Caevallho, Biomaterials 20 (1999) 27. J. Jegal, K.H. Lee, J. Appl. Polym. Sci. 72 (1999) 1755. H. Shin, M. Ueda, Sen'i Gakkaishi 55 (1999) 1. Y.C. Wei, S.M. Hudson, J.M. Mayer, D.L. Kaplan, J. Polym. Sci., A, Polym. Chem. 30 (1992) 2187. C.E. Schmidt, J.M. Baier, Biomaterials 21 (2000) 2215. F.L. Mi, H.W. Sung, S.S. Shyu, C.C. Su, C.K. Peng, Polymer 44 (2003) 6521. J. Jin, M. Song, D.J. Hourston, Biomacromolecules 5 (2004) 162. Y. Kuboe, H. Tonegawa, K. Ohkawa, H. Yamamoto, Biomacromolecules 5 (2004) 348. J. Retuert, A. Nunez, F. Martinez, Macromol. Rapid Commun. 18 (1997) 163. S.B. Park, J.O. You, H.Y. Park, S.J. Hamm, W.S. Kim, Biomaterials 22 (2001) 323. F. Garbassi, L. Balducci, Microporous Mesoporous Mater. 47 (2001) 51. K.H. Haas, Adv. Eng. Mater. 2 (2000) 571. C.K. Chan, I.M. Chu, C.F. Ou, Y.W. Lin, Mater. Lett. 58 (2004) 2243. E.V. Goncharuk, S.V. Pakhovchishin, V.I. Zarko, V.M. Gun'ko, Colloid J. 63 (2001) 283.
Synthesis and properties of chitosan/SiO2 hybrid materials Jen-Taut Yeh a,b , Chin-Lai Chen a , Kuo-Shien Huang c,⁎ a
Graduate School of Polymer Engineering, National Taiwan University of Technology, Taipei, Taiwan b Department of Textile Engineering, Nanya Institute of Technology, Jiung Li, Taiwan c Department of Polymer Materials, Kun Shan University, Yung Kang, Tainan, 71003, Taiwan Received 8 April 2006; accepted 6 July 2006 Available online 28 July 2006
Abstract This study primarily aims to explore the strength and thermal properties of various hybrid materials that are made of tetraethoxysilane/ vinyltriethoxysilane (TEOS/VTES) and chitosan in different weight ratios. It is confirmed, from micro Fourier transform infrared (micro FT-IR) and nuclear magnetic resonance (NMR) analysis, that hydrogen bonds emerge between chitosan and SiO2 in hybrid materials. With the addition of more VTES and TEOS, the surface of the hybrid material features thick granules. In addition, the mechanical performance and thermostability of both types of hybrid are better than pure chitosan. The former is enhanced with an increasing amount of TEOS until it exceeds 2.4 g and the latter is also improved with an increasing amount of TEOS. © 2006 Elsevier B.V. All rights reserved. Keywords: Strength; FT-IR; NMR; Thermal properties
1. Introduction Chitosan, which is deacetylated chitin, is low in cost, has a stable performance, and belongs to an innocuous, biolytic and active amino group [1]. It is widely used in the fields of waste water treatment, food production, textiles, agriculture and biological medicine [2–4], and even in optical equipment [5]. However, the poor water solubility of chitosan narrows its application and results in inconvenient fabrication; many researchers are therefore working on the production of water-soluble chitosan [6–8]. The unsound strength and physical properties of chitosan also deny its use in certain fields [9–12]. A convenient and effective solution to these drawbacks is to produce chitosan, as many researchers have, interlinked with glutaraldehyde [13], polyalcohol [14], polybasic carboxylic acid [15], epoxide [16] and deformed starch [17]. These, however, may all trigger toxicity problems, so natural interlinkage agents such as genipin or quinine [18–20] are more preferable. Chitosan, which is similar to cellulose in chemical constitution except for an amino group on the second carbon, can readily work with inorganic material
⁎ Corresponding author. E-mail address: [email protected] (K.-S. Huang). 0167-577X/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2006.07.016
through a sol–gel method to form hybrid materials with hydrogen bonds [21]. An effective way of synthesizing nano-hybrid materials with TEOS and organic molecules is through a sol–gel process. Such hybrid materials, which are improved in terms of the physical and chemical performances of high molecular material, have both rigid and rugged inorganic material and their organic material is multifunctional [22–24]. This study therefore proposes to synthesize hybrid materials with TEOS/VTES in different weight ratios mixed with chitosan through a sol–gel process and tests the relevant physical and chemical properties. 2. Experimental 2.1. Materials All the following are of reagent grade: chitosan (85% deacetylation; Taiwan Kaohsiung Applied Chemistry Co. Ltd), isopropanol (IPA), ammonium persulfate (the above two agents were purchased from Panreac Quimicasa, made in E.U.), glycerin, formic acid (Pharmaceutical Chemistry Corporation, Japan), tetraethoxysilane (TEOS, ACROS, USA) and vinyltriethoxysilane (VTES, ACROS, USA). The non-ion surfactant (NP-50; Taiwan Central Asia Xingye Co. Ltd) is of industrial grade.
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surface. Tensile strength and elongation properties were performed on a universal testing machine (Alphaten 400 Tester, Gau Te Machine Co. Ltd, Taiwan). The samples free from air bubbles were cut into a dumbbell shape type IV (ASTM D638). The samples were performed at 25 mm gage length with the speed of 50 mm/min and 1 kN load cell. The thermal properties of samples were measured by DuPont 2200 weight-loss analyzer (U.S.A.). The 5–10 mg samples were placed in alumina crucibles and test with a thermal ramp over a temperature range of 30–600 °C, at a heating rate of 20 °C/min under nitrogen flow speed of 20 cm3/min, after which their initial decomposition temperature (IDT) was obtained. 3. Results and discussion 3.1. FT-IR
Fig. 1. FT-IR of chitosan and hybrid materials. ((a): Chitosan, (b): VTES, (c): chitosan/VTES, (d): chitosan/TEOS, (e): chitosan/VTES–TEOS).
2.2. Methods Standard A: Formic acid was added to 4 g chitosan until the mixture reached 100 g in total. Adequate VTES, 1 g non-ion surfactant, 2 g ammonium persulfate and 200 ml distilled water were added so that the reagent in the mixture dissolved, and then perfused with nitrogen gas and reacted at 40 °C for 3 h. Standard B: 0–3.2 g TEOS and 30 ml IPAwere prepared and added to 70 ml water; the pH of the solution was regulated to about 2–3 with 0.05 M HCl and stirred for 0.5 h at room temperature. Standard B was decanted to Standard A and reacted for 2 h at 40 °C to produce gel. The constant weight gel-like product was then poured into a glass mold to obtain a sample film (1 mm) with 10 × 20 cm2 and kept at 50 °C for 2 days. The films were neutralized in a 0.5 M NaOH solution and dried at 50 °C for another 2 days under reduced pressure.
Fig. 1 shows the Fourier transform infrared (FT-IR) results of the hybrid materials. Fig. 1a shows that, due to 85% deacetylation and parts of the chitin, an absorption peak exists of N C_O and CONH at 1631 cm− 1 and 1547 cm− 1. The absorption peak of C–OH is found at 1066 cm− 1 and 1030 cm− 1 and that of C–O–C at 1150 cm− 1, indicating the presence of chitosan. Fig. 1b shows the FT-IR results of VTES. The absorption peak of the ethylene group is found at 1601 cm− 1, 961 cm− 1 and 762 cm− 1 and Si–O–C at 1048 cm− 1. It is evident in Fig. 1c and e — that the absorption peak disappeared at 961 cm− 1 and 762 cm− 1, which reveals a combined polymerization of VTES and chitosan. Fig. 1c, d and e also show absorption peaks of Si–O–Si or C–OH in the hybrid materials. The absorption scope of these two groups overlapped and it was hard to distinguish that of each group; it was therefore necessary to perform NMR analysis for further confirmation of these results. 3.2. NMR Fig. 2 shows 13C NMR analysis for chitosan and various hybrid materials. It was found that chitosan has a C_O group absorption peak
2.3. Analysis and measurement FT-IR/ATR spectra of the samples were recorded with a BioRad Digilab FTS-200 spectrometer (U.S.A.) using an MCT detector. A diamond crystal was used as internal reflectance element. Single beam spectra were the result of 64 scans. The spectral resolution was 4 cm− 1. The chemical shifts of the 13C of powdered samples were measured with a solid-state nuclear magnetic resonance (NMR) spectrometer. The samples were analyzed using a Bruker Avance 400 13C NMR spectrometer (Germany) at 50 MHz, and the spectra were observed under cross-polarization, magic angle sample spinning and power decoupling conditions with a 90° pulse and 4 s cycle time. The surface morphologies of the films were observed with a JEOL Model JSM 6400 scanning electron microscopic (Japan). A gold coating was deposited on the samples to avoid charging the
Fig. 2. 13C NMR of chitosan and hybrid materials. ((a): Chitosan, (b): chitosan/ TEOS, (c): chitosan/VTES, (d): chitosan/VTES–TEOS).
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Fig. 3. SEM of chitosan and hybrid materials. ((a) VTES/TEOS = 0/0.8 g, (b) VTES/TEOS = 0.8/0.8 g, (c) VTES/TEOS = 1.2/0 g).
at 171.4 ppm, as a result of the 85% deacetylation of chitosan and the small amount of chitin contained. Fig. 2b, c and d show the hybrid materials that are made of chitosan/TEOS, chitosan/VTES and chitosan/ VTES–TEOS, in which the C_O group absorption peak was found at 174.7, 174.8 and 174.2 ppm, respectively, shifting towards highfrequency areas. This was verified by the remaining C_O of chitosan and SiO2 that was developed from TEOS or VTES reactions and production of hydrogen bonds. The phenoma were similar as other reported studies in the literature [25,26]. 3.3. SEM Fig. 3 reveals the scanning electron microscopy (SEM) results of the hybrid materials. Fig. 3a and c shows apparent dendritic surface structures in the hybrid materials that are made of chitosan/TEOS and chitosan/ VTES, whereas Fig. 3b shows a fine-grained appearance. Therefore it is evident that the hybrid materials that are made of TEOS or VTES and that have chitosan features have an acerose surface with interspaces for less inorganic SiO2. Crystalloids are formed, and the addition of VTES and TEOS results in an increase of inorganic elements. Firm and imporous surfaces are found in the material, as noted in Fig. 3b. In addition, the surface structure of the hybrid materials that are made from the combined polymerization reaction, hydrolysis and compounding of VTES and chitosan is not clear. 3.4. Mechanical properties The mechanical properties of the hybrid materials are shown in Table 1. The tensile strength and elongation of the hybrid materials are better than those of pure chitosan and increase as the addition of VTES and TEOS is increased. When up to 0.8/2.4 g VTES and TEOS was added, respectively, all the three properties above deteriorate, which
indicates that SiO2 can harden and toughen chitosan. In addition to the content of SiO2 rising, the hydrogen bonds inside the hybrid material molecules grow and enhance the mechanical performance, whereas excessive SiO2 may result in a lower incidence of film formation and may damage the mechanical performance. 3.5. Thermal properties The thermal properties of the hybrid materials are shown in Table 1, which indicates that the hybrid materials all possess better thermostability and thermal decomposition. They improve with an increase in the amount of VTES and TEOS as reticular inorganic SiO2 is formed. The hybrid material that was made of TEOS was higher in thermostability than that of VTES because for SiO2 to take shape is hard in the poorly soluble VTES.
Table 1 Thermal and mechanic properties of chitosan and hybrid materials Weight of VTES/ TEOS (g) 0/0 c 0/0.8 0.8/0.8 0.8/1.6 0.8/2.4 0.8/3.2 1.2/0 a b c
Thermal properties a
b
Mechanic properties
Td (°C)
Tm (°C)
Char yield (%)
Tensile strength (MPa)
Elongation (%)
245 249 253 257 260 263 247
303 306 308 310 313 315 304
34.1 37.2 40.4 43.8 45.6 47.1 36.3
32.03 33.19 36.65 38.41 31.16 30.25 33.23
19.3 20.1 21.7 22.6 18.5 17.7 19.8
Temperature at 10% weight loss. Temperature at maximum weight loss. Chitosan.
J.-T. Yeh et al. / Materials Letters 61 (2007) 1292–1295
4. Conclusions This experiment, starting from synthesizing various hybrid materials with chitosan/VTES–TEOS in different ratios via a sol– gel process, explores their physical and chemical properties. The following conclusions are made from the experimental results: 1) FT-IR and NMR analyses reveal that hydrogen bonds are actually formed between chitosan and SiO2. 2) The surface structure changes with the addition of VTES and TEOS. 3) The thermostability and mechanical performances of the hybrid materials are better than pure chitosan and improve with the amount of TEOS added. However, the mechanical performance deteriorates in the case of excessive TEOS.
[8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20]
References [21] [1] Khaled F. El-tahlawy, Magda A. El-bendary, Adel G. Elhendawy, Samuel M. Hudson, Carbohydr. Polym. 60 (2005) 421. [2] A.S. Aly, B.D. Jeon, Y.H. Park, J. Appl. Polym. Sci. 65 (1997) 1939. [3] M.E.I. Badawy, E.I. Rabea, T.M. Rogge, C.V. Stevens, G. Smagghe, W. Steurbaut, M. Hofte, Biomacromolecules 5 (2004) 589. [4] G. Skjak-Braek, T. Anthonsen, Elsevier Applied Science, London, 1989. [5] S. Lu, X. Song, D. Cao, Y. Chen, K. Yao, J. Appl. Polym. Sci. 91 (2004) 3497. [6] H. Sashiwa, N. Yamamori, Y. Ichinose, J. Sunamoto, S. Aibe, Macromol. Biosci. 3 (2003) 231. [7] S. Hirano, Y. Yamaguchi, M. Kamiya, Macromol. Biosci. 3 (2003) 629.
[22] [23] [24] [25] [26]
1295
Y. Zhou, Y. Yang, D. Wang, X. Liu, Chem. Lett. 32 (2003) 682. S.J.K. Francis, H.W.T. Matthew, Biomaterials 21 (2002) 2589. X. Zeng, E. Ruckenstein, J. Membr. Sci. 148 (1998) 195. Qing Yang, Fengdong Dou, Borun Liang, Qing Shen, Carbohydr. Polym. 59 (2005) 205. Atsushi Matsuda, Toshiyuki Ikoma, Hisatoshi Kobayashi, Junzo Tanaka, Mater. Sci. Eng. 24 (2004) 723. G. Goissis, E.M. Junior, R.A.C. Marcantonio, R.C.C. Lai, D.C.J. Cancian, W.M. De Caevallho, Biomaterials 20 (1999) 27. J. Jegal, K.H. Lee, J. Appl. Polym. Sci. 72 (1999) 1755. H. Shin, M. Ueda, Sen'i Gakkaishi 55 (1999) 1. Y.C. Wei, S.M. Hudson, J.M. Mayer, D.L. Kaplan, J. Polym. Sci., A, Polym. Chem. 30 (1992) 2187. C.E. Schmidt, J.M. Baier, Biomaterials 21 (2000) 2215. F.L. Mi, H.W. Sung, S.S. Shyu, C.C. Su, C.K. Peng, Polymer 44 (2003) 6521. J. Jin, M. Song, D.J. Hourston, Biomacromolecules 5 (2004) 162. Y. Kuboe, H. Tonegawa, K. Ohkawa, H. Yamamoto, Biomacromolecules 5 (2004) 348. J. Retuert, A. Nunez, F. Martinez, Macromol. Rapid Commun. 18 (1997) 163. S.B. Park, J.O. You, H.Y. Park, S.J. Hamm, W.S. Kim, Biomaterials 22 (2001) 323. F. Garbassi, L. Balducci, Microporous Mesoporous Mater. 47 (2001) 51. K.H. Haas, Adv. Eng. Mater. 2 (2000) 571. C.K. Chan, I.M. Chu, C.F. Ou, Y.W. Lin, Mater. Lett. 58 (2004) 2243. E.V. Goncharuk, S.V. Pakhovchishin, V.I. Zarko, V.M. Gun'ko, Colloid J. 63 (2001) 283.