在非离子反相微乳液中合成二氧化硅纳米颗粒的相和分散稳定性效应

F.J. Arriagada, K. Osseo-Asare
{"title":"在非离子反相微乳液中合成二氧化硅纳米颗粒的相和分散稳定性效应","authors":"F.J. Arriagada,&nbsp;K. Osseo-Asare","doi":"10.1016/0166-6622(92)80221-M","DOIUrl":null,"url":null,"abstract":"<div><p>Silica nanoparticles synthesized by the controlled, base-catalyzed hydrolysis of tetraethoxysilane (TEOS) in cyclohexane-polyoxyethylene(5) nonylphenyl ether—water reverse microemulsions exhibit a bimodal size distribution when a relatively high water/surfactant molar ratio (<em>R</em>) is utilized. During the particle formation process there is a partial expulsion of water from the microemulsion phase and this creates a second phase of bulk water which apparently induces the formation of new silica nuclei. This reaction-promoted phase instability is attributable to the ability of ethanol, a product of TEOS hydrolysis, to shift the water solubility limit of the phase diagram to higher temperatures. At relatively low water/TEOS ratios, the resulting silica dispersions become unstable with the passage of time and eventually large flocs form. This behavior is rationalized in terms of a water-shell model according to which the presence of a water film around the silica particles facilitates the ionization of the surface silanol groups, which in turn permits the development of the necessary electrostatic stabilization. Investigation of the solubilization locale of ethanol with fluorescence techniques indicates that at low <em>R</em> there is a preferential partitioning of the alcohol to the continuous cyclohexane phase. Thus, under these conditions, ethanol molecules (which can also support silica ionization) are not available to substitute for water in the water shell.</p></div>","PeriodicalId":10488,"journal":{"name":"Colloids and Surfaces","volume":"69 2","pages":"Pages 105-115"},"PeriodicalIF":0.0000,"publicationDate":"1992-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0166-6622(92)80221-M","citationCount":"82","resultStr":"{\"title\":\"Phase and dispersion stability effects in the synthesis of silica nanoparticles in a non-ionic reverse microemulsion\",\"authors\":\"F.J. Arriagada,&nbsp;K. Osseo-Asare\",\"doi\":\"10.1016/0166-6622(92)80221-M\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>Silica nanoparticles synthesized by the controlled, base-catalyzed hydrolysis of tetraethoxysilane (TEOS) in cyclohexane-polyoxyethylene(5) nonylphenyl ether—water reverse microemulsions exhibit a bimodal size distribution when a relatively high water/surfactant molar ratio (<em>R</em>) is utilized. During the particle formation process there is a partial expulsion of water from the microemulsion phase and this creates a second phase of bulk water which apparently induces the formation of new silica nuclei. This reaction-promoted phase instability is attributable to the ability of ethanol, a product of TEOS hydrolysis, to shift the water solubility limit of the phase diagram to higher temperatures. At relatively low water/TEOS ratios, the resulting silica dispersions become unstable with the passage of time and eventually large flocs form. This behavior is rationalized in terms of a water-shell model according to which the presence of a water film around the silica particles facilitates the ionization of the surface silanol groups, which in turn permits the development of the necessary electrostatic stabilization. Investigation of the solubilization locale of ethanol with fluorescence techniques indicates that at low <em>R</em> there is a preferential partitioning of the alcohol to the continuous cyclohexane phase. Thus, under these conditions, ethanol molecules (which can also support silica ionization) are not available to substitute for water in the water shell.</p></div>\",\"PeriodicalId\":10488,\"journal\":{\"name\":\"Colloids and Surfaces\",\"volume\":\"69 2\",\"pages\":\"Pages 105-115\"},\"PeriodicalIF\":0.0000,\"publicationDate\":\"1992-12-11\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://sci-hub-pdf.com/10.1016/0166-6622(92)80221-M\",\"citationCount\":\"82\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Colloids and Surfaces\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/016666229280221M\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Colloids and Surfaces","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/016666229280221M","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 82

摘要

在环己烷-聚氧乙烯(5)壬基苯基醚-水反相微乳中,采用碱催化四乙氧基硅烷(TEOS)受控水解合成的二氧化硅纳米颗粒在较高的水/表面活性剂摩尔比(R)下呈现双峰尺寸分布。在颗粒形成过程中,水从微乳液相中部分排出,这产生了第二相的大块水,这显然诱导了新的二氧化硅核的形成。这种反应促进的相不稳定性归因于乙醇的能力,乙醇是TEOS水解的产物,可以将相图的水溶性极限转移到更高的温度。在相对较低的水/TEOS比下,所得的二氧化硅分散体随着时间的推移变得不稳定,最终形成较大的絮凝体。根据水壳模型,这种行为是合理的,根据该模型,二氧化硅颗粒周围的水膜的存在促进了表面硅醇基团的电离,这反过来又允许发展必要的静电稳定性。用荧光技术研究乙醇的增溶区域表明,在低R下,乙醇优先分配到连续的环己烷相。因此,在这些条件下,乙醇分子(也可以支持二氧化硅电离)无法替代水壳中的水。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
查看原文
分享 分享
微信好友 朋友圈 QQ好友 复制链接
本刊更多论文
Phase and dispersion stability effects in the synthesis of silica nanoparticles in a non-ionic reverse microemulsion

Silica nanoparticles synthesized by the controlled, base-catalyzed hydrolysis of tetraethoxysilane (TEOS) in cyclohexane-polyoxyethylene(5) nonylphenyl ether—water reverse microemulsions exhibit a bimodal size distribution when a relatively high water/surfactant molar ratio (R) is utilized. During the particle formation process there is a partial expulsion of water from the microemulsion phase and this creates a second phase of bulk water which apparently induces the formation of new silica nuclei. This reaction-promoted phase instability is attributable to the ability of ethanol, a product of TEOS hydrolysis, to shift the water solubility limit of the phase diagram to higher temperatures. At relatively low water/TEOS ratios, the resulting silica dispersions become unstable with the passage of time and eventually large flocs form. This behavior is rationalized in terms of a water-shell model according to which the presence of a water film around the silica particles facilitates the ionization of the surface silanol groups, which in turn permits the development of the necessary electrostatic stabilization. Investigation of the solubilization locale of ethanol with fluorescence techniques indicates that at low R there is a preferential partitioning of the alcohol to the continuous cyclohexane phase. Thus, under these conditions, ethanol molecules (which can also support silica ionization) are not available to substitute for water in the water shell.

求助全文
通过发布文献求助,成功后即可免费获取论文全文。 去求助
来源期刊
自引率
0.00%
发文量
0
期刊最新文献
author index subject index Contact angle kinetics of human albumin solutions at solid surfaces Polymerization in non-aqueous lyotropic liquid crystals: Influence of the unsaturation site Micelle dissociation kinetics study by dynamic surface tension of micellar solutions
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
现在去查看 取消
×
提示
确定
0
微信
客服QQ
Book学术公众号 扫码关注我们
反馈
×
意见反馈
请填写您的意见或建议
请填写您的手机或邮箱
已复制链接
已复制链接
快去分享给好友吧!
我知道了
×
扫码分享
扫码分享
Book学术官方微信
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术
文献互助 智能选刊 最新文献 互助须知 联系我们:info@booksci.cn
Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。
Copyright © 2023 Book学术 All rights reserved.
ghs 京公网安备 11010802042870号 京ICP备2023020795号-1