The Influence of Water Content on the Growth of the Hybrid-Silica Particles by Sol-Gel Method
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ORIGINAL PAPER
The Influence of Water Content on the Growth of the Hybrid-Silica Particles by Sol-Gel Method Xijia Zhao 1 & Yihan Wang 1 & Jianhui Luo 2,3 & Pingmei Wang 2,3 & Peiwen Xiao 2,3 & Bo Jiang 1 Received: 13 May 2020 / Accepted: 5 October 2020 # Springer Nature B.V. 2020
Abstract This paper investigates the change in size and morphology of the silica network with the change of water content by sol-gel method. Methyl triethoxysilane (MTES) and tetraethyl orthosilicate (TEOS) were used as co-precursors. The results reveal that the morphology controllable silica network are prepared by changing water content, the size of silica network is in the range in 17–176 nm. There are two ways for the silica nanoparticles to grow in the sol media, condensing with the newly hydrolyzed precursor named monomer-addition model or condensing with the existing silica structure called controlled-aggregation model. As the molar ratio of water/siloxane increases from 1 to 12, the growth process change from the aggregation of oligomers to the condensation between oligomer and hydrolyzed precursor, and the final morphology of silica nanoparticles changes from a network structure to a monodisperse particle structure. When the water content reaches a very high value with the molar ratio of water/siloxane ≥12, the growth process of silica nanoparticles is dominated by the monomer-addition mechanism. The addition of MTES as co-precursor favors the formation of the network structure. Keywords Water content . Silica nanoparticles . Sol-gel . Growth morphology
1 Introduction The Stöber method has been commonly used to prepare silica nanoparticles by hydrolysis and condensation reaction of siloxane (such as tetraethyl orthosilicate (TEOS) and methyl triethoxysilane (MTES)) in the presence of ethanol solvent, water and basic catalyst [1, 2]. Up to now, most of the reports on the growth mechanism of silica nanoparticles used one silicon source (TEOS) [3–5]. Highlight 1. Monomer-addition model and controlled-aggregation model are integrated to explain the growth mechanism of silica nanoparticles. 2. Changes in water content affect the final morphology and growth process of silica nanoparticles. * Bo Jiang [email protected] 1
Key Laboratory of Green Chemistry and Technology, College of Chemistry, Sichuan University, Chengdu 610064, China
2
Research Institute of Petroleum Exploration & Development (RIPED), PetroChina, Beijing, China
3
Key Laboratory of Nano Chemistry (KLNC), CNPC. No. 20, Xueyuan Road, Haidian District, Beijing 100083, China
However, utilizing co-precursor method to study the growth mechanism is still rarely reported [4, 6, 7]. The research results of Zhang [7] show that the introduction of different content of MTES can affect the final morphology of the silica nanoparticles, thereby changing the porosity of the sol particles and hydrophobicity and stability of the corresponding xerogel. The more content of MTES are introduced, the greater the porosity of the silica network and the better the hydrophobicity of silic
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