Background technology
The hollow inorganic microballoon receives great concern in recent years, its reason is to compare with organic hollow microsphere, the inorganic microsphere of hollow has very high heat, light, electricity, machinery and stability sour, alkali, at the controlled transportation and the delivery systme that are widely used in medicine, dyestuff, cosmetics, sensitiveness reagent such as enzyme and protein etc. as microencapsulation material, also can be used as the filler of lightweight, high selection type catalyst or catalyst carrier, and also have extremely important value at aspects such as artificial cell, medicals diagnosis on disease.
Up to now, the preparation method of the hollow microsphere of bibliographical information has a lot, mainly is template.This method is to utilize polymer microballoon such as polystyrene microsphere to be template, this microsphere surface has positive charge, the precursor that can adsorb inorganic oxide, surface at microballoon is hydrolyzed, polycondensation, form the gel of inorganic oxide, calcination by muffle furnace then, or dissolve the nuclear of polymer microballoon, thus can obtain the hollow microsphere of inorganic polymer.Though this method can successfully prepare hollow microsphere, step is various, and reunites easily in the calcination process simultaneously, and its application prospect is subjected to certain limitation, and this method also is difficult to carry out large-scale production.
Emulsion is a two-phase system, mainly contains oil/water (O/W) system and water/oil (W/O) system.Because the two-phase nature difference is bigger, has many these two-phase interfaces that are reflected to carry out.By what emulsion method prepared hollow microsphere bibliographical information arranged also, but these microballoons are matrix mostly with the organic polymer.For example, recently people such as Qunhui Sun " Journal of American Chemical Society " 2005 the 127th volumes the 23rd phase 8274-8275 page or leaf reported method by inverse emulsion polymerization in the two-phase interface prepared in reaction poly-(N-N-isopropylacrylamide) (PNIPAM) microballoon of hollow.
Also occurred preparing by the method for emulsion the report of inorganic hollow microballoon recently, for example people such as Masahiro Fujiwara has reported the hollow microsphere that has prepared silica by the interfacial reaction of water/oil/aqueous emulsion at " Chemistry of Materials " the 16th phase 5420-5426 page or leaf in 2004.This method is to utilize sodium metasilicate and suitable precipitating reagent to obtain silica in the interfacial reaction of two-phase.People such as RoyaleS.Underhill have reported that at " Chemistry of Materials " the 14th phase 4919-4926 in 2002 with neutral emulsifying agent Brij97 be emulsifying agent, are that decentralized photo, normal heptane are the reverse micro emulsion that continuous phase has formed water/oil type with water.Hydrolysis takes place at water/oily interface in octadecyl trimethoxy silane and ethyl orthosilicate, thereby polycondensation reaction forms nano level silica hollow microsphere.
Though these preparation methods can both prepare inorganic hollow microsphere, the hollow microsphere diameter that people's such as Masahiro Fujiwara method obtains big (5~20um), be difficult to the hollow microsphere that the preparation nanoscale disperses.People's such as Royale S.Underhill method is neutral emulsifying agent owing to what use, and octadecyl trimethoxy silane and ethyl orthosilicate all are oil-soluble presomas, be difficult in oil/water termination preceding picked absorption and hydrolysis takes place, therefore, be adsorbed on the presoma limited amount of oil/water termination, presoma still in oil phase, therefore obtains the silica hollow Nano microsphere of certain shell thickness and intensity very much mostly.
Summary of the invention
The purpose of this invention is to provide a kind of easy, method that can scale preparation hollow nano inorganic microsphere, to overcome the defective that prior art exists.
Technical conceive of the present invention is such:
The microemulsion that the present invention utilizes a kind of special silane emulsifying agent to form utilizes the absorption of inorganic matter presoma in oil/water termination, hydrolysis, polycondensation and post processing, the hollow nano inorganic microsphere that preparation has certain shell thickness and intensity.
Method of the present invention comprises the steps:
With emulsifiers dissolve in water, under agitation, the oil phase that is dissolved with the inorganic matter presoma is added in the above-mentioned aqueous solution, obtains the positive microemulsion, make most inorganic matter presomas be adsorbed on oil/aqueous phase interface, hydrolysis condensation reaction under 20~95 ℃ temperature, the hydrolytie polycondensation time is 6~90 hours, also can add catalyst during hydrolytie polycondensation, and slaking is 1~72 hour then, vacuum drying then can obtain the nanometer titanium dioxide micro-sphere of hollow.Particle diameter is 10~500 nanometers.
Part by weight is:
Water: oil phase: emulsifying agent=60~98: 2~40: 2~40.
Said oil phase is selected from the organic liquid immiscible with water, preferred alkane such as normal heptane, kerosene, hydrogenated kerosene, diesel oil, benzene, toluene or dimethylbenzene etc.;
The inorganic matter presoma is selected from ethyl orthosilicate, tetrabutyl titanate, isopropyl titanate etc.
Said catalyst be selected from organic or inorganic acid as: hydrochloric acid, acetic acid, oxalic acid etc. or organic or inorganic alkali such as ammoniacal liquor, triethylamine, pyridine etc., addition is 0.001~5% of an inorganic matter presoma weight;
Said emulsifying agent is selected from silane emulsifying agent or silane emulsifying agent and other common cations, the mixture of nonionic or anion emulsifier;
The silane emulsifying agent comprises the silane emulsifying agent of cationic silicon alkane emulsifying agent, nonionic silane emulsifying agent or anionic;
Cationic silane emulsifying agent structure is as follows:
R(3-n)XnSi?R′N
+R″
2R′″Y
-
In the formula: n=1~3; R is CH
3-, CH
3CH
2-or phenyl;
X is a halogen atom, as Cl, and Br, the alkoxyl of I, C1~C4, acyloxy are as CH
3COO or CH
3CH
2COO etc.;
R ' is-(CH
2)
2~8
R " is CH
3(CH
2)
0~8-;
R ' " is (CH
2)
1~30Z, wherein Z is-CH
3,-OH ,-SH or-CH=CH
2Deng functional group;
Y is a halogen atom, as Cl, and Br, I;
Or cationic silane emulsifying agent structure is as follows:
R(3-n)Xn?SiCH
2CHR′COZ(CH
2)m?N
+R″
2R′″Y
In the formula: n=1~3;
R is CH
3-or CH
3CH
2-etc.;
X is halogen atom such as Cl, Br, the alkoxyl of I, C1~C4, acyloxy such as CH
3COO or CH
3CH
2COO etc.;
R ' is H or CH
3(CH
2)
0~8Deng;
Z is O or NH etc.;
m=1~10;
R " is CH
3(CH
2)
0~8-;
R ' " is (CH
2)
1~30Z; Wherein Z is CH
3Or-OH, functional groups such as-SH;
Y is halogen atom such as Cl, Br, I etc.
In use, cationic silane emulsifying agent is not limited only to the described compound of above structure, and the cationic silane compound of other structures is available too, the cationic silane compound or the similar structures of following structure:
Or be the nonionic silane emulsifying agent of following structure:
R(3-n)XnSi(CH
2)m(CH
2CH
2O)
1Y
In the formula: n=1~3, m=1~10, l=1~40;
R is CH
3-or CH
3CH
2-;
X is halogen atom such as Cl, Br, the alkoxyl of I, C1~C4 or acyloxy such as CH
3COO, CH
3CH
2COO etc.;
Y is H, CH
3, CH
3CH
2Deng.
Or the structure of nonionic silane emulsifying agent is as follows:
R(3-n)Xn?SiCH
2CHZCOO(CH
2CH
2O)
1Y
In the formula: n=1~3; L=1~40;
R is CH
3-or CH
3CH
2-etc.;
X is halogen atom such as Cl, Br, the alkoxyl of I, C1~C4 or acyloxy such as CH
3COO, CH
3CH
2COO etc.;
Z is H, CH
3(CH
2)
0-8Deng;
Y is H, CH
3, CH
3CH
2Deng.
The structure of anion silane emulsifying agent is as follows:
Or be:
R(3-n)Xn?Si(CH
2)mY?M
In the formula: n=1~3; M=3~36
R is CH
3-or CH
3CH
2-etc.;
X is halogen atom such as Cl, Br, the alkoxyl of I, C1~C4 or acyloxy such as CH
3COO, CH
3CH
2COO etc.;
Y is SO
3 -, COO
-, SO
4 2-Deng group;
M is NH4
+, Na
+, K
+, Li
+, Mg
2+Deng cation.
Said silane emulsifying agent can adopt the laboratory synthetic method to be prepared, or adopts the commercially available prod, as the product B rij97 of Aldrich Chemical Co. company production.
The cation emulsified C that is selected from that other are common
3~C
36Long chain alkyl ammonium salt or C
3~C
36Chain alkyl quaternary alkylphosphonium salt etc.;
Other common nonionic emulsifier kinds are a lot, mainly are some low PEOs, the ester of the oligomer of oxirane and expoxy propane copolymerization or ether etc., and the commercial product of this class mainly contains the soil temperature class, spans etc.;
Other common anion emulsifiers are selected from C
3~C
36Sulfate, sulfonate or the carboxylate etc. of chain alkyl, as the sour sodium of dodecyl sulphur (sulphur), the sour sodium of detergent alkylate sulphur (sulphur), potassium or ammonia etc.;
The present invention can be according to the weight concentration that is dissolved in the inorganic matter presoma in the oil phase, control the thickness of the hollow microsphere shell that will prepare, when needs preparations thicker the hollow microsphere shell time, can improve the weight concentration of the inorganic matter presoma in the oil phase, otherwise, then reduce concentration, preferred weight concentration is 0.5~10%.
The wood invention can be according to the ratio of oil phase/water/emulsifying agent, the size of control microballoon, and preferred part by weight is:
Oil phase: water: emulsifying agent=60~98: 2~40: 2~40.
The present invention in the mechanism of preparation hollow inorganic microballoon is, silane emulsifying agent itself is arranged, or silane emulsifying agent and other emulsifying agents share the stability with good microemulsion, silane emulsifying agent itself can hydrolysis, form silicon hydroxyl (Si-OH) in oil/water termination, thereby this group runs into the inorganic matter presoma generation polycondensation that is dissolved in the oil phase and attracts more inorganic matter presoma at the interface, by hydrone on the boundary and diffusion, thereby cause the shell of oil/water termination constantly to thicken.Another mechanism of the cationic silane emulsifying agent that the present invention uses is that the electropositive of silane can effectively be adsorbed the inorganic matter presoma, can better obtain the controlled inorganic hollow microballoon of shell thickness in conjunction with above-mentioned mechanism simultaneously.
Characteristics of the present invention are, one step of method by microemulsion directly obtains particle size, the controlled hollow inorganic microballoon of shell thickness.Avoided needing at first synthetic polymer microsphere template by template.Because polymer template absorption inorganic matter presoma is limited in one's ability, the thickness of the inorganic matter shell of feasible absorption is little, and the intensity of the hollow microsphere that obtains is low.The need of having save polymer template simultaneously by the method for dissolution with solvents or calcination remove loaded down with trivial details.Therefore, the present invention prepares the hollow inorganic microballoon to have simply, is easy to do, and particle size and the adjustable advantage of shell thickness.
Below in conjunction with specific embodiment method involved in the present invention and technology are described, in following examples, the form that the structure of used silane emulsifying agent is seen below.