Effect of polyvinylpyrrolidone on the ammonia-catalyzed sol-gel process of TEOS: Study by in situ Si-29 NMR, scattering, and rheology

	Effect of polyvinylpyrrolidone on the ammonia-catalyzed sol-gel process of TEOS: Study by in situ Si-29 NMR, scattering, and rheology
	Xu, Y; Wu, D; Sun, YH; Chen, WX; Yuan, HZ; Deng, F; Wu, ZH; Wu ZH(吴忠华)
刊名	COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
	2007
卷号	305 期号:1-3 页码:#REF!
关键词	reaction kinetics siloxane Si-29 NMR SAXS rheology
通讯作者	Xu, Y (reprint author), Chinese Acad Sci, Inst Coal Chem, State Kay Lab Coal Convers, Taiyuan 030001, Peoples R China.
英文摘要	Ammonia-catalyzed sol-gel process of polyvinylpyrrolidone/tetraethoxysilane (PVP/TEOS) system in methanol was studied by in situ liquid Si-29 nuclear magnetic resonance (NMR), dynamic light scattering (DLS), small angle X-ray scattering (SAXS) and rheology. A scientific connection was established between the reaction composition and the microstructures of sol particles. It was found that the concentration of PVP played an important role in the hydrolysis kinetics of TEOS and the SiO2 sol-gel process. The results of in Situ Si-29 NMR showed that PVP addition reduced both hydrolysis rate and condensation rate of TEOS, and the condensation rate decreased more seriously than the hydrolysis rate. The particle size distributions obtained from DLS and SAXS indicated that PVP held back the growth Of SiO2 clusters by hydrogen-bonding the silanol groups on particle surface with the electronegative inner amide of PVP side chain. Thus, gelation was retarded and the rheology of sol was largely modified by PVP. Rheology study showed typical Newtonian fluid behavior before gelation and shear thinning fluid behavior after gelation point, respectively. The changes in fractal dimensions of PVP/SiO2 sols, obtained by SAXS, explained the different microstructures of SiO2 sol particles in the presence of PVP. The changes of microstructure and macroscopic properties should be pre-determined by the very early stages of sol-gel process. (c) 2007 Elsevier B.V. All rights reserved.
学科主题	Chemistry
类目[WOS]	Chemistry, Physical
收录类别	SCI
WOS记录号	WOS:000249254900015
公开日期	2016-05-03
内容类型	期刊论文
源URL	[http://ir.ihep.ac.cn/handle/311005/226121]
专题	高能物理研究所_多学科研究中心
推荐引用方式 GB/T 7714	Xu, Y,Wu, D,Sun, YH,et al. Effect of polyvinylpyrrolidone on the ammonia-catalyzed sol-gel process of TEOS: Study by in situ Si-29 NMR, scattering, and rheology[J]. COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS,2007,305(1-3):#REF!.
APA	Xu, Y.,Wu, D.,Sun, YH.,Chen, WX.,Yuan, HZ.,...&吴忠华.(2007).Effect of polyvinylpyrrolidone on the ammonia-catalyzed sol-gel process of TEOS: Study by in situ Si-29 NMR, scattering, and rheology.COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS,305(1-3),#REF!.
MLA	Xu, Y,et al."Effect of polyvinylpyrrolidone on the ammonia-catalyzed sol-gel process of TEOS: Study by in situ Si-29 NMR, scattering, and rheology".COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS 305.1-3(2007):#REF!.