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第3期 何方等：硅石气凝胶的吸水性能 .305. 阶段， 1667 (4)随热处理温度的升高，300~500℃范围内 [8]Yang H S,Choi S Y.Hyun S H.Ambient-dried low dielectric 吸水率增加明显，对应于硅石气凝胶表面有机基团 SiOz aerogel thin film.J Non Cryst Solids,1997.221:151 [9]Einarsrud M A.Kirkedelen M B.Nilsen E.Structural develop 的失去；500~700℃范围吸水率变化不大，对应于 ment of silica gels aged in TEOS.J Non Cryst Solids.1998. 相对稳定的结构状态；800℃吸水率增加迅速，可能 231.10 是由Si0的生成及挥发造成的；1000℃时吸水率反 [10]Casu M.Casula M F.Corrias A.Textural characterization of 而降低，对应于硅石气凝胶的玻璃化 high temperature silica aerogels.J Non Cryst Solids.2003. 315,97 参考文献 [11]Yoldas B E.Modification of polymer-gel structures.J Non Cryst Solids,1984,63:145 [1]Gesser H D.Goswami DC.Aerogels and related porous materi- als.Chem Rev.1989,89:765 [12]Venkateswara R A,Nilsen E,Einarsrud M A.Effect of precur- [2]Heench LL.West J K.The sol-gel process.Chem Rev.1990. sors.methylation agents and solvents on the physicochemical 90:33 properties of silica aerogels prepared by atmospheric pressure drying method.J Non Cryst Solids.2001,296:165 [3]Siouffi A M.Silica gel-based monoliths prepared by the sol-gel [13]Gallardo J,Galliano P.Thermal evolution of hybrid sol-gel silica method:facts and figures.J Chromatogr A.2003.1000:801 [4]Hrubesh L W.Aerogel applications.J Non Cryst Solids.1998. coating:a structural analysis.J Sol Gel Sci Technol.2000.19: 393 225:335 [14]Walraten G E.Hokmabadi MS.Hoimes N C.Raman spectrum [5]张秀华，赵海雷，何方，等，S02气凝胶的常压制备与表面改 and structure of thermally treated silica aerogel.J Chem Phys. 性.北京科技大学学报，2006,28(2)：157 1986,85.771 [6]YodaS,Ohshima S.Supercritical drying media modification for silica aerogel preparation.J Nom-Cryst Solids,1999.248:224 [15]Kang S K.Choi S Y.Sythesis of low-density silica gel at ambi- [7]Venkateswara R A.Kulkarni MM.Hydrophobic properties of ent pressure:effect of heat treatment.J Mater Sci.2000.35: 4971 TMOS/T MES-based silica aerogels.Mater Res Bull.2002.37: Water absorption of a silica aerogel HE Fang:ZHAO Hailei,QU Xuanhui,QIU Weihua Materials Science and Engineering School.University of Science and Technology Beijing Beijing 100083.China ABSTRACI Silica aerogels modified and unmodified with trimethylchlorosilane(T MCS)were prepared by us- ing tetraethoxysilane (TEOS)as the silica source via a two-step sol-gel method combined with supercritical CO2 drying.The water absorption of two kinds of silica aerogels was measured and the effect of heat treatment tem- perature on the water absorption of the unmodified silica aerogel was investigated.The silica aerogel modified with trimethylchlorosilane(T MCS)exhibits excellent hydrophobic behavior.For the unmodified silica aerogel, the water absorption increases apparently with heat treated temperature in the range of 300-500C,and tends to be almost unchangeable in the range of 500-700C.After heat treated at 800C,the water absorption in- creases remarkably again,whereas after heat treated at 1000Cit decreases significantly due to vitrification of the silica aerogel.The water absorption process of the silica aerogel can be divided into three stages:quick weight gain,slow weight gain and saturation.The relationship between the water absorption of the silica aerogel and its micro and chemical structures was evaluated by differential scanning calorimetry (DSC )/thermo- gravimetry (TG),infrared spectra(IR),and N2 absorption techniques. KEY WORDS silica:aerogel:water absorption;surface modification;sol-gel method阶段． （4） 随热处理温度的升高300～500℃范围内 吸水率增加明显对应于硅石气凝胶表面有机基团 的失去；500～700℃范围吸水率变化不大对应于 相对稳定的结构状态；800℃吸水率增加迅速可能 是由 SiO 的生成及挥发造成的；1000℃时吸水率反 而降低对应于硅石气凝胶的玻璃化． 参 考 文 献 ［1］ Gesser H DGoswami D C．Aerogels and related porous materials．Chem Rev198989：765 ［2］ Heench L LWest J K．The so-l gel process．Chem Rev1990 90：33 ［3］ Siouffi A M．Silica ge-l based monoliths prepared by the so-l gel method：facts and figures．J Chromatogr A20031000：801 ［4］ Hrubesh L W．Aerogel applications．J Non Cryst Solids1998 225：335 ［5］ 张秀华赵海雷何方等．SiO2 气凝胶的常压制备与表面改 性．北京科技大学学报200628（2）：157 ［6］ Yoda SOhshima S．Supercritical drying media modification for silica aerogel preparation．J Non-Cryst Solids1999248：224 ［7］ Venkateswara R AKulkarni M M．Hydrophobic properties of T MOS／T MES-based silica aerogels．Mater Res Bull200237： 1667 ［8］ Yang H SChoi S YHyun S H．Ambient-dried low dielectric SiO2aerogel thin film．J Non Cryst Solids1997221：151 ［9］ Einarsrud M AKirkedelen M BNilsen E．Structural development of silica gels aged in TEOS．J Non Cryst Solids1998 231：10 ［10］ Casu MCasula M FCorrias A．Textural characterization of high temperature silica aerogels．J Non Cryst Solids2003 315：97 ［11］ Yoldas B E．Modification of polymer-gel structures．J Non Cryst Solids198463：145 ［12］ Venkateswara R ANilsen EEinarsrud M A．Effect of precursorsmethylation agents and solvents on the physicochemical properties of silica aerogels prepared by atmospheric pressure drying method．J Non Cryst Solids2001296：165 ［13］ Gallardo JGalliano P．Thermal evolution of hybrid so-l gel silica coating：a structural analysis．J Sol Gel Sci Technol200019： 393 ［14］ Walraten G EHokmabadi M SHoimes N C．Raman spectrum and structure of thermally treated silica aerogel．J Chem Phys 198685：771 ［15］ Kang S KChoi S Y．Sythesis of low-density silica gel at ambient pressure：effect of heat treatment．J Mater Sci200035： 4971 Water absorption of a silica aerogel HE FangZHAO HaileiQU XuanhuiQIU Weihua Materials Science and Engineering SchoolUniversity of Science and Technology BeijingBeijing100083China ABSTRACT Silica aerogels modified and unmodified with trimethylchlorosilane （T MCS） were prepared by using tetraethoxysilane （TEOS） as the silica source via a two-step so-l gel method combined with supercritical CO2 drying．The water absorption of two kinds of silica aerogels was measured and the effect of heat treatment temperature on the water absorption of the unmodified silica aerogel was investigated．The silica aerogel modified with trimethylchlorosilane （T MCS） exhibits excellent hydrophobic behavior．For the unmodified silica aerogel the water absorption increases apparently with heat-treated temperature in the range of 300－500℃and tends to be almost unchangeable in the range of 500－700℃．After heat-treated at 800℃the water absorption increases remarkably againwhereas after heat-treated at 1000℃ it decreases significantly due to vitrification of the silica aerogel．The water absorption process of the silica aerogel can be divided into three stages：quick weight gainslow weight gain and saturation．The relationship between the water absorption of the silica aerogel and its micro and chemical structures was evaluated by differential scanning calorimetry （DSC ）／thermogravimetry （TG）infrared spectra （IR）and N2absorption techniques． KEY WORDS silica；aerogel；water absorption；surface modification；so-l gel method 第3期 何 方等： 硅石气凝胶的吸水性能 ·305·