CN1111133C

CN1111133C - One-component sol-gel technique

Info

Publication number: CN1111133C
Application number: CN01114128A
Authority: CN
Inventors: 王策; 张亚红; 郭娜
Original assignee: Jilin University
Current assignee: Jilin University
Priority date: 2001-06-21
Filing date: 2001-06-21
Publication date: 2003-06-11
Anticipated expiration: 2021-06-21
Also published as: CN1330037A

Abstract

The present invention belongs to a single-component body sol-gel technology. High purity inorganic single-block materials with optical performance and with silicon dioxide as the single component are prepared at a room temperature. The technology of the present invention has the advantages of simple preparation route, convenient operation and short flow path (about 5 days). Obtained single gel blocks have the advantages of controllable shape, no crack, small volume contraction and good optical performance.

Description

One-component sol one gel process for preparing

The invention belongs to one-component sol-gel technique.

Sol-gel (sol-gel) technology be a kind of be raw material with the metal alkoxide, under mild conditions through steps such as hydrolysis, polycondensation, gel, ageing, drying and densifications, change gel into by colloidal sol, and then sintering is made the processing method of glass, pottery and other inorganic materials.Compare with the glass melting method of routine, the advantage of sol-gel method is its relatively low temperature of reaction, can be in the initial period of material processing on the nanoscale structure to material control, the homogeneity and the purity of prepared material height.These advantages of sol-gel method make it obtain at aspects such as oxide abrasive and coating, film, oxide powder and fibers using widely.Yet, but utilize this traditional sol-gel technology but to be difficult to realize the preparation of block inorganic materials, thus limited their commercial applications.

The subject matter that exists is: (1) gel time is long.Usually a complete block gel preparation course usually needs several months even 1 year at normal temperatures.(2) serious volumetric shrinkage.If is solvent with alcohol, when being initial reactant with the alkoxyl silicone, final gel volume generally only is 5% of a reactant initial soln volume, and this will bring a series of problem to the moulding of block gel, as can't moulding, typing etc.(3) serious be full of cracks.Because the effect of the capillary force of material internal, even dry carefully block gel for a long time in case be placed in the air, also can take place cracked completely.(4) expensive and environmental pollution.In the sol-gel process, whole forming process is undertaken by a large amount of solvent evaporates, and this certainly will cause solvent to reclaim and consequence such as environment is contaminated.So, how to obtain block silica dioxide gel in the short period of time and do not chap, be still utilize the Sol-Gel technology prepare in the inorganic block gelatinous material the problem that must solve.

At above-mentioned four problems, people such as Wang Ce have invented bulk sol-gel technique (application number: 98116544.3).It is under mild conditions by be in raw material acidic hydrolysises such as metal alkoxide in the tetrahydrofuran (THF) (THF), add carbonate gel promotor, utilize aliphatic solvent to extract THF, steps such as bulk sol cast molding, gel, densification with obtaining constitute.The technological improvement of two keys is to have used carbonate gel promotor and has obtained bulk sol solution.Compare with traditional Sol-Gel technology and be prepared as example with silica monoliths, the silica monoliths preparation cycle foreshortens to a week, and volumetric shrinkage is reduced to below 50%, and the solvent of product percent of pass 10%, 80% can obtain reclaiming, but material surface is coarse.Analysis revealed, SiO ₂Relatively low and the rough reason of block success ratio may be that carbonate also falls for complete and hydrochloric acid neutralization reaction, and a part of salt particle is added to SiO ₂In the gel.Thereby the salt particulate is at SiO ₂The inner stress that produces causes these defectives to occur.Thus, people such as Wang Ce has further invented the compound mass sol-gel technology.

Compound mass sol-gel technology (application number: be to utilize to have the SiO of ratio 99118655.9) ₂Metal oxide (the TiO that electronegativity is low ₂, ZrO ₂) colloidal sol replaces the carbonate powder in the bulk sol-gel technique, thereby outside the advantage that guarantees the bulk sol gelation process, also overcome gel promotor and SiO ₂The problem of phase tolerance makes SiO ₂The success ratio of gel monolithic improves greatly.Yet, because a small amount of TiO of this technology ₂(ZrO ₂) introducing of colloidal sol, caused final prepared SiO ₂Gel monolithic optical property descends, and volumetric shrinkage also increases.Therefore, how to prepare in the short period of time that volumetric shrinkage is little, the gel monolithic that do not chap the time, can keep the high purity and the good optical character of gel monolithic again, remain at preparation SiO ₂The huge challenge that we faced in the gel monolithic process.

The present invention is a kind of one-component sol-gel technique.It is in preparation silica monoliths process, remove to replace carbonate in the bulk sol-gel technique and the oxide compound in the compound mass sol-gel technology with a kind of silicane linking agent, rely on this class linking agent under acidic conditions rapidly and the silicon dioxide gel characteristic of carrying out chemically crosslinked, guaranteeing under the little condition of same controllable shapes and volumetric shrinkage, shorten gel and time of drying again, improve product purity, success ratio and optical property.

Be 1 at first, at room temperature: 2.5-4: 0.01-0.05: 1-5 mixed oxyalkyl silicon compound Si (OC according to mol ratio ₂H ₅) ₄, water, hydrochloric acid (2M), tetrahydrofuran (THF), stir until forming clear solution, at 60-70 ℃ of following backflow 1-3 hour, be cooled to room temperature at last then, obtain SiO ₂Sol solution.Get a certain amount of this colloidal sol, be 1 according to mol ratio: the ratio of 0.01-0.1 adds a kind of linking agent, wherein with 1: and 0.02-0.06, stir and remove tetrahydrofuran (THF) with organic solvent extraction after 1-5 minute.Wherein linking agent is R ' Si (OR) ₂R " (R=C _nH _2n+1R '=H, F, Cl, Br; R "=H, F, Cl, Br, OC _nH _2n+1N=1 wherein, 2), generally control R ' _nSi (OR) _4-n(R '=H, or Cl; R=OC ₂H ₅N=1 or 2).Organic solvent comprises that all can form the solvent that two-phase can be dissolved each other with any ratio with tetrahydrofuran (THF) again with sol solution, as: benzene,toluene,xylene, pentane, hexane, heptane, hexanaphthene etc.After the extracting and demixing, take off a layer bulk sol, water and cast from the difform plastic containers,, seal up and seal film, and prick several holes, to treat the residual solvent volatilization with syringe needle as: disc, cylindricality, sphere, octagon, square, semicircle or the like.At room temperature place about five days, can obtain the good SiO of difform optical property ₂The gel monolithic.

Embodiment 1

In the 250ml round-bottomed flask, add the 31.5g tetraethoxy, the 6.75g deionized water, 0.75ml hydrochloric acid (2M), the 21.26g tetrahydrofuran (THF) at room temperature stirs till the disappearance that is separated, and at 60 ℃ of following backflow 2-3 hours, obtains SiO then ₂Sol solution 1.Get 20g solution 1, add the triethoxyl silane [HSi (OC of 4% (accounting for the silicon sol mol ratio) ₂H ₅) ₃] and stirred 2 minutes, add the 50ml hexanaphthene then and rocked 2 minutes, the appearance that is separated.Collect the bulk sol of lower floor, water and cast from the plastic containers, seal up and seal film, and prick several holes, to treat solvent evaporates with syringe needle.Colloidal sol begins to solidify after 30 minutes, places about a week under air-tight state, can obtain different shapes SiO ₂The gel monolithic.The thermal weight loss test result shows that dioxide-containing silica is 89%.Experimental result shows that the success ratio of this gel monolithic is more than 90%.Volumetric shrinkage is 75% (reaching theoretical value), and its optical property is unaffected.

Embodiment 2

Change the HSi (OC among the embodiment 1 ₂H ₅) ₃Be diethoxy silane [H ₂Si (OC ₂H ₅) ₂], other experimental procedure and conditionally complete are with embodiment 1.The bulk sol of collecting solidified in 10 minutes.The SiO that obtains ₂Gel monolith surface slickness is not as embodiment 1.

Embodiment 3

Change the HSi (OC among the embodiment 1 ₂H ₅) ₃Be methyl ethoxy silane [H ₂Si (OC ₂H ₅) (CH ₃)], other experimental procedure and conditionally complete are with embodiment 1, and the bulk sol of collection solidified in 10 minutes, the gel monolithic SiO that obtains ₂Content is lower than embodiment 1.

Embodiment 4

Change the HSi (OC among the embodiment 1 ₂H ₅) ₃Be diethylsilane [H ₂Si (CH ₃) ₂], other experimental procedure and conditionally complete are with embodiment 1.The bulk sol of collecting solidified the gel monolithic SiO that obtains in 15 minutes ₂Content and hardness are lower than embodiment 1.

Embodiment 5

Change the HSi (OC among the embodiment 1 ₂H ₅) ₃Be triethoxy chlorosilane [ClSi (OC ₂H ₅) ₃] other experimental procedure and conditionally complete be with embodiment 1.The bulk sol of collecting solidified the SiO that obtains in 20 minutes ₂The gel monolithic is with embodiment 1.Embodiment 6

The triethoxyl silane that changes among the embodiment 1 is triethoxy silicon fluoride [FSi (OC ₂H ₅) ₃], other experimental procedure and conditionally complete are with embodiment 1.The bulk sol of collecting solidified the SiO that obtains in 60 minutes ₂The gel monolithic is with embodiment 1.

Embodiment 7

The content that changes the triethoxyl silane among the embodiment 1 increases to 10% from 4%, and other experimental procedure and conditionally complete are with embodiment 1, and the bulk sol that obtains is gel after several seconds, the SiO of acquisition ₂The single transparent degree is relatively poor, and contains a large amount of bubbles.

Embodiment 8

Experimental procedure and conditionally complete are with embodiment 1, and the hexanaphthene that only changes among the embodiment 1 is other aliphatic hydrocarbon, as Skellysolve A, and normal hexane and normal heptane, the result who obtains is fully identical with embodiment 1.

Embodiment 9

Experimental procedure and conditionally complete are with embodiment 1, and the hexanaphthene that only changes among the embodiment 1 is an aromatic hydrocarbon, as benzene, and toluene and dimethylbenzene, the silica monoliths that obtains is muddy shape.

Claims

1, a kind of one-component sol-gel preparation method is characterized in that adopting Si (OC ₂H ₅) ₄, water, concentration is hydrochloric acid, the tetrahydrofuran (THF) of 2M, at room temperature mixes, stirs, and until forming clear solution, at 60-70 ℃ of following backflow 1-3 hour, is cooled to room temperature at last then, obtains silicon sol solution; Getting a certain amount of this solution, is 1 according to mol ratio: the ratio of 0.01-0.1 adds a kind of linking agent R ' Si (OR) ₂R " R=C in the formula _nH _2n+1R '=H or F, CI, Br; R "=H or F, Cl, Br, OC _nH _2n+1N=1 or 2 wherein, stir and add the organic solvent extraction tetrahydrofuran (THF) after 1-5 minute, after the extracting and demixing, take off a layer bulk sol, water and cast from the difform plastic containers, seal up and seal film, and prick several holes with syringe needle, to treat solvent evaporates, at room temperature placed five days, promptly obtain the good SiO of difform optical property ₂The gel monolithic.

2, one-component sol-gel preparation method as claimed in claim 1 is characterized in that Si (OC ₂H ₅) ₄, water, hydrochloric acid, tetrahydrofuran (THF) mol ratio be 1: 2.5-4: 0.01-0.05: 1-5.

3, one-component sol-gel preparation method as claimed in claim 1 or 2 is characterized in that the linking agent that uses is R ' _nSi (OR) _4-nWherein R '=H, or CI; R=OC ₂H ₅N=1 or 2.

4, one-component sol-gel preparation method as claimed in claim 1 is characterized in that the mol ratio that linking agent accounts for silicon sol is 1: 0.02-0.06.

5, as claim 1,2 or 3 described one-component sol-gel preparation methods, the organic solvent that it is characterized in that being used to extracting tetrahydrofuran (THF) is benzene or toluene, dimethylbenzene, pentane, hexane, heptane, hexanaphthene.

6, as claim 1 or 5 described one-component sol-gel preparation methods, the organic solvent that it is characterized in that being used to extracting tetrahydrofuran (THF) is a hexanaphthene.

7,, it is characterized in that casting and be shaped as disc, cylindricality, sphere, octagon, square, semicircle as claim 1,2,3 or 5 described one-component sol-gel preparation methods.