Synthesis of Mesoporous Silica Materials Using the Reactive Urea-formaldehyde Resin Polymerized in situ as Template

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1 Vol. 64, , ACTA CHIMICA SINICA No. 8, * ( ) ( ). BET,...,., / [n( ) n( ) 2]. ; ; ; ; Synthesis of Mesoporous Silica Materials Using the Reactive Urea-formaldehyde Resin Polymerized in situ as Template GUO, Bin LIU, Hui HAO, Zhi-Xian* GAN, Li-Hua XU, Zi-Jie CHEN, Long-Wu (Department of Chemistry, Tongji University, Shanghai ) Abstract A simple one-step procedure was described for the synthesis of mesoporous monolith and composite sphere, in which hydrolyzation of tetraethyl orthosilicate and polymerization of urea with formaldehyde occurred at the same time. The analysis of the liquid nitrogen adsorption demonstrated that the pore sizes of the monoliths and the composite spheres were both uniform. Morphologies of the composite spheres characterized by SEM were smooth or of network, which depended on the relative concentrations of the reactants. As the molar ratio of formaldehyde to urea exceeded the limit of 2.0, the synthesis by varying initial concentration of the reactants yielded the monoliths with controllable pore sizes. From the analysis of the FTIR and DTA, the urea-formaldehyde resin with branched chains in its molecular structure was considered as an inducing agent in the pore formation of the monolith. Keywords mesoporous silica; template; urea-formaldehyde resin; composite powder; monolith [1 5] Mobile MCM- 41 [6],,. ( [7] ),,, [8 10]., [1 6,8 11], * haozhixian@mail.tongji.edu.cn Received June 24, 2005; revised November 8, 2005; accepted December 21, (No ).

2 No , D- D- -L- [12] ; [13] ; ( [14] [15] [16] ). -ZrO 2 -TiO 2, [17]., [18] 4 µm. Arafa [19],..., : (, 98.5%, ); (, 99.7%, ); (, 99.0%, ); (, 37.0% 40.0%,, 38.0% ); (, 36.0% 38.0%,, 37.0% ), ml 50 ml 15 ml (TEOS) 20 ml 50 ml, n(teos) n(hcl) n(h 2 O) n(etoh) h,, 20 min, 20 h., 55, ph min., 70 2 d., 90 2 d,., d. 600, 2 h. 1.3 Thermo Nicolet NEXUS ; CDR-1 ; Micromeritics Tristar 3000 ; Philips XL-30 (20 kv). 2 (U) (TEOS) , (F), 1,. 1 Table 1 Molar ratios of reactants and the weight of composite sphere n( ) n( ) n(teos) /g F 0.0 U 1.0 S F 0.5 U 1.0 S F 1.0 U 1.0 S F 1.5 U 1.0 S F 2.0 U 1.0 S F 3.0 U 1.0 S F 4.0 U 1.0 S F 9.0 U 3.0 S , ,.

3 758 Vol. 64, BET 600 SiO 2 6 nm, 680 m 2 /g, 1.0 cm 3 /g, 50 m 2 /g., 90,. 2 BET ,. 2 BET Table 2 BET characterization data of the monolith silicas synthesized with two different molar ratios of formaldehyde to urea a / nm / (m 2 g 1 ) / (m 2 g 1 ) / (cm 3 g 1 ) F 0.27 U 0.27 S F 0.53 U 0.53 S F 1.0 U 1.0 S F 1.6 U 1.6 S F 0.81 U 0.27 S F 1.6 U 0.53 S F 3.0 U 1.0 S F 4.8 U 1.6 S m 2 /g, cm 3 /g, F 1.0 U S 1.6. Wang [20],. 1 F 1.0 U 1.0 S 1.6 BJH Figure 1 BJH pore size distributions of F 1.0 U 1.0 S 1.6 (a) before calcination; (b) after calcination a 1, ,, 14 nm, 290 m 2 /g, 1.1 cm 3 /g ; ,, nm 5.51 nm, m 2 /g m 2 /g, cm 3 /g cm 3 /g F 1.0 U 1.0 S 1.6 F 4.8 U 1.6 S F 4.8 U 1.6 S 1.6 F 1.0 U 1.0 S 1.6, F 4.8 U 1.6 S 1.6 F 1.0 U 1.0 S 1.6. BET, F 1.0 U 1.0 S m 2 /g, cm 3 /g,. F 4.8 U 1.6 S F 4.8 U 1.0 S 1.6 BJH Figure 2 BJH pore size distributions of F 4.8 U 1.0 S 1.6 (a) before calcination; (b) after calcination 2.2 SEM 3,., F 1.6 U 1.6 S 1.6,., (6 nm), BET.,. F 4.8 U 1.6 S 1.6 ( 1 µm),.

4 No / SEM Figure 3 SEM images of the samples prepared by varying initial molar ratios of formaldehyde to urea (a) F 1.6 U 1.6 S 1.6 powders before calcination; (b) F 4.8 U 1.6 S 1.6 powders before calcination; (c) F 4.8 U 1.6 S 1.6 monolith before calcination; (d) F 1.6 U 1.6 S 1.6 powders after calcination; (e) F 4.8 U 1.6 S 1.6 powders after calcination; (f) F 4.8 U 1.6 S 1.6 monolith after calcination F 1.6 U 1.6 S 1.6 F 4.8 U 1.6 S 1.6,. BET,. F 4.8 U 1.6 S 1.6 3c,, FT-IR cm 1 N H O H, (Si OH) (CH 2 OH) cm 1 Si O Si [19], F 1.0 U 1.0 S 1.6, ( 1 ), 90%,, cm 1 C N, [21] cm 1 (CH 2 OH) [22,23],,,.,, 1 n( ) n( ) Figure 4 IR spectra of the composite monoliths prepared by varying the molar ratio of formaldehyde to urea 2.4 DTA 5, 100. F 0.0 U 1.0 S 1.6, F.50 U 1.0 S 1.6 F 1.0 U 1.0 S , [18,19]. F 2.0 U 1.0 S 1.6, F 3.0 U 1.0 S 1.6, F 4.0 U 1.0 S 1.6,, 300,.,

5 760 Vol. 64, 2006,. 5 Figure 5 DTA of the composite monoliths prepared by varying the molar ratio of formaldehyde to urea 3,., BET,,.,,,,..,. 3 Stein, A.; Melde, B. J.; Schroden, R. C. Adv. Mater. 2000, 12, De Vos, D. E.; Dams, M.; Sels, B. F.; Jacobs, P. A. Chem. Rev. 2002, 102, Stein, A. Adv. Mater. 2003, 15, Kresge, C. T.; Leonowicz, M. E.; Roth, W. J.; Vartuli, J. C.; Beck, J. S. Nature 1992, 359, Yao, N.; Xiong, G.-X.; He, M.-Y.; Sheng, W.-S.; Yang, W.-S.; Bao, X.-H. Chem. Mater. 2002, 14, Schulz-Ekloff, G.; Rathousky, J.; Zukal, A. J. Inorg. Mater. 1999, 1, Che, S.; Kamiya, S.; Terasaki, O.; Tatsumi, T. J. Am. Chem. Soc. 2001, 123, Zhao, D.-Y.; Yang, P.-D.; Melosh, N. Adv. Mater. 1998, 10, El-Safty, S. A.; Hanaoka, T. Chem. Mater. 2004, 16, Wei, Y.; Jin, D.-L.; Ding, T.-Z.; Shih, W.-H.; Liu, X.-H.; Stephen, Z. D. C.; Fu, Q. Adv. Mater. 1998, 10, Pang, J.-B.; Qiu, K.-Y.; Wei, Y. Microporous Mesoporous Mater. 2000, 40, Ogasawara, W.; Shenton, W.; Davis, S. A.; Mann, S. Chem. Mater. 2000, 12, Pedroni, V.; Schulz, P. C.; Gschaider de Ferreira, M. E.; Morini, M. A. Colloid Polym. Sci. 2000, 278, Coradin, T.; Livage, J. J. Sol-Gel Sci. Technol. 2003, 26, Yang, J.-J.; Zuo, Y.-M. Chem. J. Chin. Univ. 2000, 21, 1852 (in Chinese). (,,, 2000, 21, 1852.) 18 Guo, R.; Yu, J.-G.; Zhao, L.; Zhao, X.-J. Acta Chim. Sinica 2004, 62, 493 (in Chinese). (,,,,, 2004, 62, 493.) 19 Arafa, I. M.; Fares, M. M.; Barham, A. S. Eur. Polym. J. 2004, 40, Wang, X.-Z.; Li, W.-H.; Zhu, G.-S.; Qiu, S.-L.; Zhao, D.-Y.; Zhong, B. Microporous Mesoporous Mater. 2004, 71, Ye, S.; Ran, Q.-Y.; Wu, W.-Z.; Mao, X.-W. Thermochim. Acta 1995, 253, Haase, F.; Sauer, J. J. Am. Chem. Soc. 1995, 117, Minopoulou, E.; Dessipri, E.; Chryssikos, G. D.; Gionis, V.; Paipetis, A.; Panayiotou, C. Int. J. Adhes. Adhes. 2003, 23, 473. References 1 Sayari, A. Chem. Mater. 1996, 8, Corma, A. Chem. Rev. 1997, 97, (A DING, W. F.; DONG, H. Z.)