Application of lactam as solvent in nanomaterial preparation

Abstract

The present invention disclosed use of lactam as a solvent in the preparation of nanomaterials by precipitation method, sol-gel method or high temperature pyrolysis. These methods are able to recycle lactam solvent, which meet requirements of environmental protection.

Claims

1. A precipitation method for synthesis of nanomaterials, comprising the following steps: adding 0.01-100 weight parts of precursor and 100 weight parts of lactam solvent into a reactor to form a mixture; stirring the mixture at 80-200° C. for 0.1-2 hr wherein the lactam solvent becomes a molten lactam solvent in which the precursor is fully dissolved or dispersed, when stirring, adding 0.05-50 weight parts of precipitant, at a temperature of 80-250° C. and a time of 0.1-200 hr to obtain precipitate; washing the precipitate with water to obtain washed precipitate; centrifuging the washed precipitate to obtain centrifuged precipitate; and drying the centrifuged precipitate to obtain synthesized nanomaterials; wherein the precursor is selected from the group consisting of soluble inorganic metal salts of halogen, nitrate, nitrite, sulfate, sulfite or carbonate anions and organic compounds of metals or metalloids; wherein the lactam contained in the lactam solvent is one or more substances selected from cyclic amides or cyclic amide derivatives; wherein the general structural formula of the cyclic amides is: ##STR00003## wherein the general structural formula of the cyclic amide derivatives is: ##STR00004## wherein R is a substance selected from the group consisting of hydrogen, halogen, alkyl, hydroxy, alkoxy and acyl; wherein the precipitant is selected from the group consisting of alkali metals, alkali metal oxides, alkali metal hydroxides, alkali metal organic salts, ammonia, compounds able to release ammonia by pyrolysis, soluble inorganic salts formed by metal elements and halogen elements, soluble inorganic salts formed by metal elements and chalcogens, soluble inorganic salts formed by metal elements and carbonate, and soluble inorganic salts formed by metal elements and sulfate; and wherein the nanomaterials are substances containing inorganic particles having a particle size of greater than 1 nm and less than or equal to 100 nm; the content of the inorganic particles is no less than 0.01% of the substance; the inorganic particles are mixtures composed of one or more substances selected from the group consisting of hydroxides, oxides, sulfides, metals and inorganic salts.

2. The method according to claim 1, wherein alkali metals are selected from Li, Na or K; wherein alkali metal oxides are selected from the group consisting of Na.sub.2O, K.sub.2O, Na.sub.2O.sub.2 and K.sub.2O.sub.2; wherein alkali metal hydroxides are selected from the group consisting of NaOH and KOH; wherein alkali metal organic salts are selected from the group consisting of sodium methoxide, sodium ethoxide, sodium phenoxide, potassium oleate, sodium lactam and potassium caprolactam; wherein ammonia and compounds able to release ammonia by pyrolysis are selected from the group consisting of ammonia gas, ammonia water, urea, ammonium carbonate and ammonium bicarbonate; wherein soluble inorganic salts formed by metal elements and halogen elements are selected from the group consisting of NaCl, KCl, MgCl.sub.2, CaCl.sub.2, AlCl.sub.3.6H.sub.2O, FeCl.sub.2.4H.sub.2O and FeCl.sub.3.6H.sub.2O; wherein soluble inorganic salts formed by metal elements and chalcogens are selected from the group consisting of Na.sub.2S, K.sub.2S, Na.sub.2S.9H.sub.2O, Na.sub.2Se and NaHTe; wherein soluble inorganic salts formed by metal elements and carbonate are selected from the group consisting of Na.sub.2CO.sub.3 and K.sub.2CO.sub.3; and wherein soluble inorganic salts formed by metal elements and sulfate are selected from the group consisting of Na.sub.2SO.sub.4 and K.sub.2SO.sub.4.

3. The method according to claim 1, wherein during synthesis of nanomaterials by the precipitation method, after adding precipitant, further adding 0.05-50 weight parts of reductant.

4. The method of claim 1, wherein the precursor is selected from the group consisting of zinc acetate, carbonyl iron, iron acetylacetonate, iron oleate, butyl titanate and tetraethyl orthosilicate.

5. The method of claim 1, wherein the general structural formula of the cyclic amides is selected from valerolactam, caprolactam, oenantholactam, 2-azacyclononanone, nonanoylamide, caprinlactam, undecanoylamide, laurolactam, glutarimide or adipimide; and wherein in the cyclic amide derivatives, halogen is selected from fluorine, chlorine, bromine or iodine; alkyl is selected from methyl, ethyl or propyl; and alkoxy is selected from methoxy, ethoxy or propoxy; and acyl is selected from acetyl or propionyl.

6. The method of claim 1, wherein the cyclic amide derivatives are selected from N-methylvalerolactam, N-methylcaprolactam, N-vinylcaprolactam or N-methoxycaprolactam.

7. The method according to claim 1, wherein in the inorganic particles, the hydroxides are water-insoluble or slightly water-soluble inorganic compounds formed by one or more than one metal elements and hydroxyl, and are mixtures composed of one or more substances selected from the group consisting of Ni(OH).sub.2, Mg(OH).sub.2, Al(OH).sub.3, Nd(OH).sub.3, Y(OH).sub.3, Mg—Al hydrotalcite and Zn—Al hydrotalcite; wherein the oxides are water-insoluble or slightly water-soluble inorganic compounds formed by one or more metal elements and metalloid elements and oxygen, and are mixtures composed of one or more substances selected from the group consisting of Ag.sub.2O, ZnO, Cu.sub.2O, Fe.sub.3O.sub.4, SiO.sub.2, MgAl.sub.2O.sub.4 and CaTiO.sub.3; wherein the sulfides are water-insoluble or slightly water-soluble inorganic compounds formed by binding metal elements or metalloid elements with sulfur, selenium, tellurium, arsenic or antimony, and are mixtures composed of one or more substances selected from the group consisting of CuS, ZnS, CdS, CdSe, CdTe, WSe.sub.2, CuTe, CoAs.sub.2 and GaAs; wherein the metals are water-insoluble or slightly water-soluble substances composed of one or more of metal elements selected from Group IIIA, IVA, IB, IIB or VIII in the periodic table of elements, and are alloys or mixtures composed of one or more substances selected from the group consisting of Fe, Ni, Cu, Ag, Pd, Pt, Au and Ru; and wherein the inorganic salts are water-insoluble or slightly water-soluble inorganic compounds formed by binding positive ions of metal elements with carbonate, sulfate, silicate or halogen negative ions, and are mixtures composed of one or more substances selected from the group consisting of CaCO.sub.3, MgCO.sub.3, BaSO.sub.4, CaSiO.sub.3, AgCl, AgBr and CaF.sub.2.

8. A sol-gel method for synthesis of nanomaterials with lactam as the solvent comprising the steps: adding 0.01-100 weight parts of hydrolyzable precursor and 100 weight parts of lactam solvent into a reactor to form a mixture; stirring the mixture at 80-150° C. for 0.1-2 hr to make the lactam solvent molten and to fully dissolve and disperse the hydrolysable precursor in the molten lactam solvent, and adding 0.01-50 weight parts of water for hydrolysis with the hydrolysis temperature of 80˜250° C. and hydrolysis time of 0.01-48 hr to obtain sol; performing gelatinization on the sol in the reactor at 80˜270° C. for 0.01-96 hr to obtain a gelatinized mixture; washing the gelatinized mixture with absolute alcohol to obtain a washed mixture; and drying the washed mixture to obtain synthesized nanomaterials; wherein the hydrolyzable precursor is selected from the group consisting of inorganic metal salts of halogen, nitrate, sulfate or acetate anions and metal organics, wherein the lactam contained in the lactam solvent is one or more substances selected from the group consisting of cyclic amides and cyclic amide derivatives, wherein the general structural formula of the cyclic amide is: ##STR00005## the general structural formula of the cyclic amide derivatives is: ##STR00006## wherein R is a substance selected from hydrogen, halogen, alkyl, hydroxy, alkoxy or acyl; and wherein the nanomaterials are substances containing inorganic particles having a particle size of greater than 1 nm and less than or equal to 100 nm; the content of the inorganic particles is no less than 0.01% of the substance; the inorganic particles are mixtures composed of one or more substances selected from the group consisting of hydroxides, oxides, sulfides, metals and inorganic salts.

9. The method according to claim 8, wherein synthesis of nanomaterials by the sol-gel method, further comprises, after hydrolysis, adding 0.05-50 weight parts of reductant.

10. The method as in claim 8 wherein the hydrolyzable inorganic salts are selected from the group consisting of FeCl.sub.2.4H.sub.2O, FeCl.sub.3, FeCl.sub.3.6H.sub.2O, Fe(NO.sub.3).sub.3.6H.sub.2O, Fe.sub.2(SO.sub.4).sub.3, AlCl.sub.3, AlCl.sub.3.6H.sub.2O, CuSO.sub.4.5H.sub.2O, CuCl.sub.2, CuCl.sub.2.2H.sub.2O, TiCl.sub.3, TiCl.sub.4 and Zn(OAc).sub.2.2H.sub.2O; and wherein metal organics are selected from the group consisting of diethyl aluminium chloride, aluminum isopropoxide, diethyl zinc, tetraethyl orthosilicate, butyl titanate and tetraethyl titanate.

11. A high temperature pyrolysis method for synthesis of nanomaterials with lactam as the solvent comprising the steps: adding 0.01-100 weight parts of pyrolyzable precursor and 100 weight parts of lactam solvent into a reactor to form a mixture; stirring the mixture at 80-150° C. for 0.1-2 hr to create a molten lactam solvent from the lactam solvent and to fully dissolve or disperse the pyrolyzable precursor in the molten lactam solvent; performing pyrolysis on the molten lactam solvent by raising the temperature to 100˜270° C. for 0.1-20 hr whereby a pyrolysis product is formed; washing the pyrolysis product with absolute alcohol; and drying the washed pyrolysis product to obtain synthesized nanomaterials, wherein the pyrolyzable precursor is selected from soluble inorganic salts pyrolyzable in solvent at a temperature of no higher than 280° C. or from metal organics pyrolyzable in solvent at a temperature of no higher than 280° C., wherein the lactam contained in the lactam solvent is one or more of the substances selected from cyclic amides or cyclic amide derivatives, wherein the general structural formula of the cyclic amide is: ##STR00007## wherein the general structural formula of the cyclic amide derivatives is: ##STR00008## wherein R is a substance selected from hydrogen, halogen, alkyl, hydroxy, alkoxy or acyl, and wherein the nanomaterials are substances containing inorganic particles having a particle size of greater than 1 nm and less than or equal to 100 nm; the content of the inorganic particles is no less than 0.01% of the substance; the inorganic particles are mixtures composed of one or more substances selected from hydroxides, oxides, sulfides, metals or inorganic salts.

12. The method according to claim 11, wherein the soluble inorganic salts pyrolyzable in solvent at the temperature of no higher than 280° C. are selected from the group consisting of AgNO.sub.3, FeCl.sub.3, Zn(OAc).sub.2 and TiCl.sub.4; and wherein the metal organics pyrolyzable in solvent at the temperature of no higher than 280° C. are selected from the group consisting of oleate, levulinate and carbonyl salts.

13. The method according to claim 11, further comprising, after adding lactam, adding 0.05-50 weight parts of anion donors.

14. The method according to claim 13, wherein the anion donors are compounds pyrolyzable at the temperature of less than or equal to 280° C. and able to produce anions required for synthesis of nanomaterials, and are selected from the group consisting of benzyl alcohol, trioctylphosphine oxide, and tetramethylthiuram disulfide.

15. The method according to claim 11, further comprising the step, before pyrolysis at the temperature of 100-270° C., adding 0.05-50 weight parts of reductant.

16. The method according to claim 3, 9 or 15, wherein the reductant is selected from the group consisting of ascorbic acid, potassium borohydride, sodium borohydride, hydrazine, hydrazine hydrate, hydroxylamine and aldehyde group-containing organics.

17. The method according to claim 1, claim 8, or claim 11, further comprising the step, after adding lactam solvent, adding 0.01-20 weight parts of stabilizer or 0.1-80 weight parts of insoluble inorganics.

18. The method according to claim 17, wherein the stabilizer is selected from the group consisting of anionic surfactant, cationic surfactant, amphoteric surfactant and nonionic surfactant that adjusts the morphology of synthetic nanomaterials, wherein anionic surfactant is selected from the group consisting of sodium dodecyl sulfate, sodium alkyl benzene sulfonate and sodium oleate; cationic surfactant is selected from the group consisting of tetrapropylammonium hydroxide, tetrapropylammonium bromide, tetrapropylammonium chloride, cetyltrimethylammonium bromide, cetyltrimethylammonium chloride anddodecyltrimethylammonium bromide; amphoteric surfactant is selected from the group consisting of dodecyl ethoxysulfobetaine, octadecyl 2 hydroxyethyl amine oxide and octadecanamide dimethylamine oxide; and nonionic surfactant is selected from the group consisting of triblock copolymer, polyethylene glycol, polyvinyl pyridine, glycerol and 2-mercaptopropionic acid.

19. The method according to claim 17, wherein the insoluble inorganics are substances that are the carrier or attachment point for synthesis of nanomaterials and are selected from the group consisting of activated carbon, graphene, carbon fibers, carbon nanotubes, molecular sieves, smectite clay, diatomaceous earth, glass fibers and glass microspheres.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 (.sup.13C-NMR) before and after use of caprolactam solvent for synthesis of nano-Mg(OH).sub.2 powder with the method in Embodiment 1.

(2) FIG. 2 X-ray diffraction diagram of synthetic nano-Mg(OH).sub.2 powder with the method in Embodiment 1.

(3) FIG. 3 Scanning electron microscopy image of synthetic nano-Mg(OH).sub.2 powder with the method in Embodiment 1.

(4) FIG. 4 Transmission electron microscopy image of synthetic nano-Nd(OH).sub.3 powder with the method in Embodiment 2.

(5) FIG. 5 Transmission electron microscopy image of synthetic nano-Al(OH).sub.3/Y(OH).sub.3 powder with the method in Embodiment 3.

(6) FIG. 6 X-ray diffraction diagram of synthetic nano-Ag.sub.2O powder with the method in Embodiment 5.

(7) FIG. 7 Transmission electron microscopy image of synthetic nano-Ag.sub.2O powder with the method in Embodiment 5.

(8) FIG. 8 X-ray diffraction diagram of synthetic nano-ZnO powder with the method in Embodiment 6.

(9) FIG. 9 Scanning electron microscopy image of synthetic nano-ZnO powder with the method in Embodiment 6.

(10) FIG. 10 Scanning electron microscopy image of synthetic nano-ZnO powder with the method in Embodiment 7.

(11) FIG. 11 Scanning electron microscopy image of synthetic nano-ZnO powder with the method in Embodiment 8.

(12) FIG. 12 X-ray diffraction diagram of synthetic nano-CuO powder with the method in Embodiment 14.

(13) FIG. 13 Transmission electron microscopy image of synthetic nano-CuO powder with the method in Embodiment 14.

(14) FIG. 14 X-ray diffraction diagram of synthetic nano-Fe.sub.3O.sub.4 powder with the method in Embodiment 15.

(15) FIG. 15 Transmission electron microscopy image of synthetic nano-Fe.sub.3O.sub.4 powder with the method in Embodiment 15.

(16) FIG. 16 Magnetization curve measured by Superconductivity Quantum Interference Device (SQUID) of synthetic nano-Fe.sub.3O.sub.4 powder with the method in Embodiment 15.

(17) FIG. 17 Transmission electron microscopy image of synthetic nano-ZnS powder with the method in Embodiment 19.

(18) FIG. 18 Transmission electron microscopy image of synthetic nano-CdTe powder with the method in Embodiment 21.

(19) FIG. 19 Transmission electron microscopy image of synthetic nano-Ag powder with the method in Embodiment 22.

(20) FIG. 20 Transmission electron microscopy image of synthetic nano-Ag powder with the method in Embodiment 23.

(21) FIG. 21 Transmission electron microscopy image of synthetic nano-Cu powder with the method in Embodiment 25.

(22) FIG. 22 Transmission electron microscopy image of synthetic nano-Fe.sub.2O.sub.3 powder with the method in Embodiment 27.

(23) FIG. 23 Transmission electron microscopy image of synthetic nano-TiO.sub.2 powder with the method in Embodiment 32.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(24) Further explanations are made to this invention in combination with the embodiments shown in the following diagrams.

Embodiment 1

(25) Use of Caprolactam as Solvent for Synthesis of Nano-Mg(OH).sub.2 by Precipitation Method

(26) Add 20.3 g MgCl.sub.2.6H.sub.2O into 100 g molten caprolactam (purity of caprolactam ≧80%, moisture ≦20%) and stir at 100° C. for 30 min to make MgCl.sub.2 fully dissolved. When stirring, rapidly add 10 g ammonia water (containing ammonia: 26%) and keep at constant temperature of 100° C. for 24 hr. Wash the obtained mixture with 200 g deionized water by centrifugation for three times, and obtain nano-Mg(OH).sub.2 powder after intensive drying and crushing.

(27) FIG. 1 shows .sup.13C-NMR before and after use of caprolactam solvent, deuterated chloroform is used as a solvent, and the spectrum keeps unchanged before and after use of caprolactam solvent, indicating that caprolactam solvent can be recycled. FIG. 2 is the X-ray diffraction diagram of synthetic nano-Mg(OH).sub.2 powder with the method in this Embodiment, and at the double diffraction angles 2θ=18.7°, 38.0°, 50.8° and 58.8°, the number of JCPDS card corresponding to the diffraction peak in comparison database is 44-1482, belonging to typical brucite crystal form, indicating that the product is high-purity Mg(OH).sub.2. Moreover, diffraction peak broadening is generally due to particle size refinement, indicating that the synthetic Mg(OH).sub.2 is small in particle size. However, diffraction peak intensity is still high, indicating that the synthetic material has high degree of crystallinity. FIG. 3 is the scanning electron microscopy (SEM) image of synthetic nano-Mg(OH).sub.2 powder with the method in this Embodiment, and the observation results show that Mg(OH).sub.2 powder is composed of regular hexagonal flaky nanoparticles of about 10 nm in thickness and about 80 nm in long diameter. Mg(OH).sub.2/PA6 nanocomposite can be obtained by mixing this Mg(OH).sub.2 powder as the filler, when the adding amount reaches 80 weight parts, Mg(OH).sub.2/PA6 nanocomposite can reach level V-0 inflaming retarding effect, and the tensile strength and notched impact strength still remain at 69.5 and 11.2 kJ/m.sup.2 (the results are tested respectively according to ASTM-D638 and D6110 standard).

Embodiment 2

(28) Use of Caprolactam as Solvent for Synthesis of Nano-Nd(OH).sub.3 by Precipitation Method

(29) Add 10.96 g Nd(NO.sub.3).sub.3.6H.sub.2O into 100 g molten caprolactam (purity of caprolactam ≧80%, moisture ≦20%) and stir at 200° C. for 30 min to make Nd(NO.sub.3).sub.3.6H.sub.2O fully dissolved. When stirring, rapidly add 3 g NaOH and keep at constant temperature of 200° C. for 24 hr. Wash the obtained mixture with 200 g deionized water by centrifugation for three times, and obtain nano-Nd(OH).sub.3 powder after intensive drying and crushing. FIG. 4 is transmission electron microscopy (TEM) image of synthetic nano-Nd(OH).sub.3 powder with the method in this Embodiment, and the observation results show that Nd(OH).sub.3 powder is composed of evenly dispersed rodlike nanoparticles of about 40 nm is mean length and about 7 nm in mean diameter.

Embodiment 3

(30) Use of Caprolactam as Solvent for Synthesis of Nano-Al(OH).sub.3/Y(OH).sub.3 Compound by Precipitation

(31) Add 3.83 g Y(NO.sub.3).sub.3.6H.sub.2O and 4.02 g AlCl.sub.3.9H.sub.2O (molar ratio: [Y.sup.3+]/[Al.sup.3+]=3/5) into 100 g molten caprolactam (purity of caprolactam ≧80%, moisture ≦20%) and stir at 200° C. for 30 min to make Y(NO.sub.3).sub.3.6H.sub.2O and AlCl.sub.3.9H.sub.2O fully dissolved. When stirring, rapidly add 8 g NaOH and keep at constant temperature of 200° C. for 24 hr. Wash the obtained mixture with 200 g deionized water by centrifugation for three times, and obtain nano-Al(OH).sub.3/Y(OH).sub.3 powder after intensive drying and crushing. FIG. 5 is TEM image of synthetic nano-Al(OH).sub.3/Y(OH).sub.3 powder with the method in this Embodiment, and the observation results show that the product is aggregated by small particles of about 5 nm in diameter.

Embodiment 4

(32) Use of Valerolactam as Solvent for Synthesis of Nano-Mg—Al Hydrotalcite by Precipitation Method

(33) Add 2.03 g MgCl.sub.2.6H.sub.2O and 3.33 g Al.sub.2(SO.sub.4).sub.3.18H.sub.2O into 100 g molten valerolactam (purity of valerolactam >80%, moisture ≦20%) and stir at 120° C. for 30 min to make the raw materials fully dissolved, and add 1.4 g NaOH and 1.86 g Na.sub.2CO.sub.3 and keep at constant temperature of 150° C. for 24 hr. Wash the obtained mixture with 200 g deionized water by centrifugation for three times, and obtain nano-Mg—Al hydrotalcite powder after intensive drying and crushing.

Embodiment 5

(34) Use of Caprolactam as Solvent for Synthesis of Nano-Ag.sub.2O by Precipitation Method

(35) Add 4.24 g AgNO.sub.3 into 100 g molten caprolactam (purity of caprolactam ≧60%, moisture ≦30%) and stir at 80° C. for 30 min to make AgNO.sub.3 fully dissolved. When stirring, rapidly add 1 g NaOH and keep at constant temperature of 100° C. for 2 hr. Wash the obtained mixture with 200 g deionized water by centrifugation for three times, and obtain nano-Ag.sub.2O powder after intensive drying and crushing. FIG. 6 is the X-ray diffraction diagram (XRD) of synthetic nano-Ag.sub.2O powder with the method in this Embodiment, and positions and intensity of all the diffraction peaks perfectly match the JCPDS card 65-6811 of Ag.sub.2O in the database, indicating that the product is high-purity Ag.sub.2O. Moreover, diffraction peak broadening is generally due to particle size refinement, indicating that the synthetic Ag.sub.2O is small in particle size. However, diffraction peak intensity is still high, indicating that the synthetic material has high degree of crystallinity. FIG. 7 is TEM image of synthetic nano-Ag.sub.2O powder with the method in this Embodiment, and the observation results show that Ag.sub.2O powder is composed of monodisperse spherical particles of about 5 nm in diameter.

Embodiment 6

(36) Use of Caprolactam as Solvent for Synthesis of Nano-ZnO by Precipitation Method

(37) Add 3.41 g ZnCl.sub.2 into 100 g molten caprolactam (purity of caprolactam ≧80%, moisture ≦20%) and stir at 150° C. for 30 min to make ZnCl.sub.2 fully dissolved. When stirring, rapidly add 2 g NaOH and keep at constant temperature of 100° C. for 2 hr. Wash the obtained mixture with 200 g deionized water by centrifugation for three times, and obtain nano-ZnO powder after intensive drying and crushing. FIG. 8 is the X-ray diffraction diagram (XRD) of synthetic nano-ZnO powder with the method in this Embodiment, and positions and intensity of all the diffraction peaks perfectly match the JCPDS card 36-1451 of zincite ZnO in the database, indicating that the product is high-purity ZnO. Moreover, diffraction peak broadening is generally due to particle size refinement, indicating that the synthetic ZnO is small in particle size. However, diffraction peak intensity is still high, indicating that the synthetic material has high degree of crystallinity and is very applicable to luminescent materials. FIG. 9 is SEM image of synthetic nano-ZnO powder with the method in this Embodiment, and the observation results show that ZnO powder is composed of spherical particles of about 8 nm in diameter and can be used for semiconductor luminescent quantum dots.

Embodiment 7

(38) Use of Valerolactam as Solvent for Synthesis of Nano-ZnO by Precipitation Method

(39) Add 3.41 g ZnCl.sub.2 into 100 g molten valerolactam (purity of valerolactam ≧80%, moisture ≦20%) and stir at 150° C. for 30 min to make ZnCl.sub.2 fully dissolved. When stirring, rapidly add 2 g NaOH and keep at constant temperature of 100° C. for 2 hr. Wash the obtained mixture with 200 g deionized water by centrifugation for three times, and obtain nano-ZnO powder after intensive drying and crushing FIG. 10 is SEM image of synthetic nano-ZnO powder with the method in this Embodiment, and the observation results show that the product is composed of monodisperse spherical particles of about 5 nm in diameter.

Embodiment 8

(40) Use of Laurolactam as Solvent for Synthesis of Nano-ZnO by Precipitation Method

(41) Add 3.41 g ZnCl.sub.2 into 100 g molten laurolactam (purity of laurolactam ≧90%, moisture ≦5%) and stir at 160° C. for 30 min to make ZnCl.sub.2 fully dissolved. When stirring, rapidly add 2 g NaOH and keep at constant temperature of 100° C. for 2 hr. Wash the obtained mixture with 200 g deionized water by centrifugation for three times, and obtain nano-ZnO powder after intensive drying and crushing. FIG. 11 is SEM image of synthetic nano-ZnO powder with the method in this Embodiment, and the observation results show that the product is composed of monodisperse spherical particles of about 20 nm in diameter.

Embodiment 9

(42) Use of Caprolactam/Laurolactam as Mixed Solvent for Synthesis of Nano-ZnO by Precipitation Method

(43) Add 3.41 g ZnCl.sub.2 into mixed lactam solvent composed of 80 g caprolactam and 20 g laurolactam (purity of caprolactam and laurolactam ≧90%, moisture ≦5%) and stir at 160° C. for 30 min to make ZnCl.sub.2 fully dissolved. When stirring, rapidly add 2 g NaOH and keep at constant temperature of 100° C. for 2 hr. Wash the obtained mixture with 200 g deionized water by centrifugation for three times, and obtain nano-ZnO powder after intensive drying and crushing, with the size of about 12 nm.

Embodiment 10

(44) Use of Caprolactam/N-Methylcaprolactam as Mixed Solvent for Synthesis of Nano-ZnO by Precipitation Method

(45) Add 3.41 g ZnCl.sub.2 into mixed lactam solvent composed of 80 g caprolactam and 20 g N-methylcaprolactam (purity of caprolactam and N-methylcaprolactam ≧90%, moisture ≦5%) and stir at 160° C. for 30 min to make ZnCl.sub.2 fully dissolved. When stirring, rapidly add 2 g NaOH and keep at constant temperature of 100° C. for 2 hr. Wash the obtained mixture with 200 g deionized water by centrifugation for three times, and obtain nano-ZnO powder after intensive drying and crushing, with the size of about 10 nm.

Embodiment 11

(46) Use of Valerolactam/Caprolactam/Laurolactam as Mixed Solvent for Synthesis of Nano-ZnO by Precipitation Method

(47) Add 3.41 g ZnCl.sub.2 into mixed lactam solvent composed of 20 g valerolactam, 60 g caprolactam and 20 g laurolactam (purity of caprolactam ≧90%, moisture ≦5%; purity of valerolactam and laurolactam ≧80%, moisture ≦20%) and stir at 160° C. for 30 min to make ZnCl.sub.2 fully dissolved. When stirring, rapidly add 2 g NaOH and keep at constant temperature of 100° C. for 2 hr. Wash the obtained mixture with 200 g deionized water by centrifugation for three times, and obtain nano-ZnO powder after intensive drying and crushing, with the size of about 10 nm, indicating that the size of synthetic nanomaterials can be effectively adjusted by changing the components of lactam solvent.

Embodiment 12

(48) Use of Adipimide as Mixed Solvent for Synthesis of Nano-ZnO by Precipitation Method

(49) Add 3.41 g ZnCl.sub.2 into 100 g molten adipimide (purity of adipimide ≧90%, moisture ≦5%) and stir at 160° C. for 30 min to make ZnCl.sub.2 fully dissolved. When stirring, rapidly add 2 g NaOH and keep at constant temperature of 100° C. for 2 hr. Wash the obtained mixture with 200 g deionized water by centrifugation for three times, and obtain nano-ZnO powder after intensive drying and crushing.

Embodiment 13

(50) Use of N-Methylcaprolactam as Solvent for Synthesis of Nano-ZnO by Precipitation Method

(51) Add 3.41 g ZnCl.sub.2 into 100 g molten N-methylcaprolactam (purity of N-methylcaprolactam ≧99%, moisture <0.2%) and stir at 160° C. for 30 min to make ZnCl.sub.2 fully dissolved. When stirring, rapidly add 2 g NaOH and keep at constant temperature of 100° C. for 8 hr. Wash the obtained mixture with 200 g deionized water by centrifugation for three times, and obtain nano-ZnO powder after intensive drying and crushing.

Embodiment 14

(52) Use of Caprolactam as Solvent for Synthesis of Nano-CuO by Precipitation Method

(53) Add 6.242 g CuSO.sub.4.5H.sub.2O into 100 g molten caprolactam (purity of caprolactam ≧80%, moisture ≦20%) and stir at 100° C. for 30 min to make CuSO.sub.4.5H.sub.2O fully dissolved. When stirring, rapidly add 2 g NaOH and keep at constant temperature of 100° C. for 2 hr. Wash the obtained mixture with 200 g deionized water by centrifugation for three times, and obtain nano-CuO powder after intensive drying and crushing. FIG. 12 is the X-ray diffraction diagram (XRD) of synthetic nano-CuO powder with the method in this Embodiment, and positions and intensity of all the diffraction peaks perfectly match the JCPDS card 44-0706 of CuO in the database, indicating that the product is high-purity CuO. Moreover, diffraction peak broadening is generally due to particle size refinement, indicating that the synthetic CuO is small in particle size. FIG. 13 is TEM image of synthetic nano-CuO powder with the method in this Embodiment, and the observation results show that the product is composed of monodisperse and narrow-distributed spherical particles of about 3.5 nm in diameter.

Embodiment 15

(54) Use of Caprolactam as Solvent for Synthesis of Nano-Fe.sub.3O.sub.4 by Precipitation Method

(55) Add 4.1 g FeCl.sub.2.4H.sub.2O and 8.2 g FeCl.sub.3.6H.sub.2O into 100 g molten caprolactam (purity of caprolactam ≧80%, moisture ≦20%) and stir at 150° C. for 30 min to make them fully dissolved. When stirring, rapidly add 9.8 g KOH and keep at constant temperature of 100° C. for 2 hr. Wash the obtained mixture with 200 g deionized water by centrifugation for three times, and obtain nano-Fe.sub.3O.sub.4 powder after intensive drying and crushing. FIG. 14 is the X-ray diffraction diagram (XRD) of synthetic nano-Fe.sub.3O.sub.4 powder with the method in this Embodiment, and positions and intensity of all the diffraction peaks perfectly match magnetite Fe.sub.3O.sub.4 in the database, indicating that the product is high-purity Fe.sub.3O.sub.4. Moreover, diffraction peak broadening is generally due to particle size refinement, indicating that the synthetic Fe.sub.3O.sub.4 is small in particle size. FIG. 15 is TEM image of synthetic nano-Fe.sub.3O.sub.4 powder with the method in this Embodiment, and the observation results show that the product is composed of spherical particles of about 5 nm in diameter. FIG. 16 is magnetization curve measured by Superconductivity Quantum Interference Device (SQUID), and the results show that Fe.sub.3O.sub.4 powder is a super-paramagnetic material, with the saturation magnetization of 40 emu/g, and is very applicable to magnetic separation and MRI.

Embodiment 16

(56) Use of Caprolactam as Solvent for Synthesis of Nano-MgCO.sub.3 by Precipitation Method

(57) Add 20.3 g MgCl.sub.2.6H.sub.2O into 100 g molten caprolactam (purity of caprolactam ≧80%, moisture ≦20%) and stir at 100° C. for 30 min to make MgCl.sub.2 fully dissolved. When stirring, rapidly add 15 g Na.sub.2CO.sub.3 and keep at constant temperature of 100° C. for 24 hr. Wash the obtained mixture with 200 g deionized water by centrifugation for three times, and obtain nano-MgCO.sub.3 powder after intensive drying and crushing. The product is in flake structure, with the thickness of about 5 nm and long diameter of 60 nm.

Embodiment 17

(58) Use of Caprolactam as Solvent for Synthesis of Nano-BaSO.sub.4 by Precipitation Method

(59) Add 5.6 g BaCl.sub.2 into 100 g molten caprolactam (purity of caprolactam ≧80%, moisture ≦20%) and stir at 100° C. for 30 min to make MgCl.sub.2 fully dissolved. When stirring, rapidly add 3.0 g Na.sub.2SO.sub.4 and keep at constant temperature of 100° C. for 24 hr. Wash the obtained mixture with 200 g deionized water by centrifugation for three times, and obtain nano-BaSO.sub.4 powder after intensive drying and crushing. The product is in flake structure, with the thickness of about 4 nm and long diameter of 90 nm.

Embodiment 18

(60) Use of Caprolactam as Solvent for Synthesis of Nano-AgCl by Precipitation Method

(61) Add 2.1 g AgNO.sub.3 into 100 g molten caprolactam (purity of caprolactam ≧80%, moisture ≦20%) and stir at 100° C. for 30 min to make AgNO.sub.3 fully dissolved. When stirring, rapidly add 1.5 g NaCl and keep at constant temperature of 100° C. for 24 hr. Wash the obtained mixture with 200 g deionized water by centrifugation for three times, and obtain nano-AgCl powder after intensive drying and crushing. The product is composed of spherical particles, with the size of about 3 nm.

Embodiment 19

(62) Use of Caprolactam as Solvent for Synthesis of Nano-ZnS by Precipitation Method

(63) Add 10.0 g ZnCl.sub.2 into 100 g molten caprolactam (purity of caprolactam ≧80%, moisture ≦20%) and stir at 100° C. for 30 min to make ZnCl.sub.2 fully dissolved. When stirring, rapidly add 12.0 g Na.sub.2S.9H.sub.2O and keep at constant temperature of 150° C. for 12 hr. Wash the obtained mixture with 200 g deionized water by centrifugation for three times, and obtain nano-ZnS powder after intensive drying and crushing. FIG. 17 is TEM image of synthetic nano-ZnS powder with the method in this Embodiment, and the observation results show that the product is composed of spherical particles of about 20 nm in diameter.

Embodiment 20

(64) Use of Caprolactam as Solvent for Synthesis of Nano-CdSe by Precipitation Method

(65) Add 7.71 g Cd(NO.sub.3).sub.2.2H.sub.2O into 100 g molten caprolactam (purity of caprolactam ≧80%, moisture ≦20%) and stir at 100° C. for 30 min to make Cd(NO.sub.3).sub.2.2H.sub.2O fully dissolved. When stirring, rapidly add 3 g Na.sub.2Se and keep at constant temperature of 150° C. for 12 hr. Wash the obtained mixture with 200 g deionized water by centrifugation for three times, and obtain nano-CdSe powder after intensive drying and crushing.

Embodiment 21

(66) Use of Caprolactam as Solvent for Synthesis of Nano-CdTe by Precipitation Method

(67) Add 0.82 g Cd(NO.sub.3).sub.2.2H.sub.2O and 0.54 ml 2-mercaptopropionic acid (stabilizer) into 100 g molten caprolactam (purity of caprolactam ≧90%, moisture ≦1%) and stir at 80° C. for 30 min to make Cd(NO.sub.3).sub.2.2H.sub.2O and 2-mercaptopropionic acid fully dissolved. Under the protection of nitrogen, rapidly add 0.5 g NaHTe and keep at constant temperature of 90° C. for 14 hr. Wash the obtained mixture with 200 g deionized water by centrifugation for three times, and obtain nano-CdTe powder after intensive drying and crushing FIG. 18 is TEM image of synthetic nano-CdTe powder with the method in this Embodiment, and the observation results show that the product is composed of monodisperse spherical particles of about 5 nm in diameter and is very applicable to luminescent devices as semiconductor quantum dots.

Embodiment 22

(68) Use of Caprolactam as Solvent for Synthesis of Nano-Ag by Precipitation Method

(69) Add 4.24 g AgNO.sub.3 into 100 g molten caprolactam (purity of caprolactam ≧80%, moisture ≦20%) and stir at 100° C. for 30 min to make AgNO.sub.3 fully dissolved. When stirring, rapidly add 1 g NaOH and keep at constant temperature of 100° C. for 2 hr, and then add 2 g NaBH for continued reaction for 1 hr. Wash the obtained mixture with 200 g deionized water by centrifugation for three times, and obtain nano-Ag powder after intensive drying and crushing. FIG. 19 is TEM image of synthetic nano-Ag powder with the method in this Embodiment, and the observation results show that the product is composed of spherical particles of about 6 nm in diameter. This nano-Ag powder can be stably dispersed in water, alcohol and other solvents, and the dispersion liquid can be directly used as conductive adhesive and antibacterial agent.

Embodiment 23

(70) Use of Caprolactam as Solvent for Synthesis of Nano-Ag by Precipitation Method

(71) Add 4.24 g AgNO.sub.3 and 10 g cetyltrimethylammonium bromide into 100 g molten caprolactam (purity of caprolactam ≧95%, moisture ≦1%) and stir at 100° C. for 30 min to make AgNO.sub.3 and cetyltrimethylammonium bromide fully dissolved. When stirring, rapidly add 1 g NaOH and keep at constant temperature of 100° C. for 2 hr, and then add 2 g NaBH for continued reaction for 1 hr. Wash the obtained mixture with 200 g deionized water by centrifugation for three times, and obtain nano-Ag powder after intensive drying and crushing. FIG. 20 is TEM image of synthetic nano-Ag powder with the method in this Embodiment, and the observation results show that the product is composed of rodlike particles of about 15 nm in diameter and about 200 nm in length.

Embodiment 24

(72) Use of Caprolactam as Solvent for Synthesis of Nano-Ag Plated Glass Microspheres by Precipitation Method

(73) Add 4.24 g AgNO.sub.3 and 10 g glass microspheres (mean diameter is about 15 um) into 100 g molten caprolactam (purity of caprolactam ≧80%, moisture ≦20%) and stir at 100° C. for 1 hr to make glass microspheres fully dispersed. When stirring, rapidly add 1 g NaOH and keep at constant temperature of 100° C. for 30 min, and then add 2 g glucose for continued reaction for 12 hr. Wash the obtained mixture with 200 g deionized water by centrifugation for three times, and obtain nano-Ag plated glass microspheres after intensive drying and crushing. The nano-Ag plated glass microspheres can be used as an antibacterial component to be added in polymers and metals and as an electricity and heat conductive filler to be added in plastic and rubber.

Embodiment 25

(74) Use of Caprolactam as Solvent for Synthesis of Nano-Cu by Co-Precipitation Method

(75) Add 6.242 g CuSO.sub.4.5H.sub.2O into 100 g molten caprolactam (purity of caprolactam ≧80%, moisture ≦20%) and stir at 100° C. for 30 min to make CuSO.sub.4.5H.sub.2O fully dissolved. When stirring, rapidly add 1 g NaOH and keep at constant temperature of 120° C. for 2 hr, and then add 4 g ascorbic acid for reaction for 12 hr. Wash the obtained mixture with 200 g deionized water by centrifugation for three times, and obtain nano-Cu powder after intensive drying and crushing. FIG. 21 is TEM image of synthetic nano-Cu powder with the method in this Embodiment, and the observation results show that the product is composed of rodlike particles of about 300×30 nm in diameter.

Embodiment 26

(76) Use of Caprolactam as Solvent for Preparation Activated Carbon Loaded Nano-Pd by Precipitation Method

(77) Add 5.0 g PdCl.sub.2 and 10 g activated carbon (carrier) into 100 g molten caprolactam (purity of caprolactam ≧80%, moisture ≦20%) and stir at 100° C. for 30 min to make PdCl.sub.2 fully dissolved. When stirring, rapidly add 1 g NaOH and keep at constant temperature of 100° C. for 2 hr, and then add 2 g KBH.sub.4 for continued reaction for 2 hr. Wash the obtained mixture with 200 g deionized water by centrifugation for three times, and obtain activated carbon loaded nano-Pd after intensive drying and crushing. This activated carbon loaded nano-Pd has high catalytic activity in hydrogenation reduction of nitrobenzene-containing compounds to aminobenzene compound, and in catalytic hydrogenation of paranitrotoluene to produce 4-methylaniline, the conversion rate is 90% and the selectivity is 98%.

Embodiment 27

(78) Use of Caprolactam as Solvent for Synthesis of Nano-Fe.sub.2O.sub.3 by Sol-Gel Method

(79) Add 8.2 g FeCl.sub.3.6H.sub.2O into 100 g molten caprolactam (purity of caprolactam ≧95%, moisture ≦1%) and stir at 80° C. for 30 min, add 5 g deionized water for hydrolysis reaction at 100° C. for 24 hr, and then vacuumize to remove water and shift to crystallization at 180° C. for 8 hr. Wash the obtained mixture with 200 g absolute alcohol by centrifugation for three times, and obtain nano-Fe.sub.2O.sub.3 powder after intensive drying and crushing. FIG. 22 is TEM image of synthetic nano-Fe.sub.2O.sub.3 powder with the method in this Embodiment, and the observation results show that the product is composed of particles of about 3 nm in diameter.

Embodiment 28

(80) Use of Caprolactam as Solvent for Synthesis of Nano-Al(OH).sub.3 by Sol-Gel Method

(81) Add 6.4 g AlCl.sub.3 into 100 g molten caprolactam (purity of caprolactam ≧99.5%, moisture ≦0.1%) and stir at 80° C. for 30 min, slowly add 10 g deionized water for hydrolysis reaction at 100° C. for 24 hr, and then vacuumize to remove water and shift to crystallization at 150° C. for 24 hr. Wash the obtained mixture with 200 g absolute alcohol by centrifugation for three times, and obtain nano-Al(OH).sub.3 powder after intensive drying and crushing. The powder is composed of irregular flaky particles of 2 nm in thickness.

Embodiment 29

(82) Use of Caprolactam as Solvent for Synthesis of Nano-SiO.sub.2 by Sol-Gel Method

(83) Add 6 g tetraethyl orthosilicate into 100 g molten caprolactam (purity of caprolactam ≧60%, moisture ≦30%) and stir at 150° C. for 30 min, add 20 g deionized water for hydrolysis reaction at 120° C. for 15 hr, and then vacuumize to remove water and shift to crystallization at 200° C. for 24 hr. Wash the obtained mixture with 200 g absolute alcohol by centrifugation for three times, and obtain nano-SiO.sub.2 powder after intensive drying and crushing, with the size of 50 nm.

Embodiment 30

(84) Use of Caprolactam as Solvent for Synthesis of Nano-SiO.sub.2 by Sol-Gel Method

(85) Add 6 g tetraethyl orthosilicate into 100 g molten caprolactam (purity of caprolactam ≧60%, moisture ≦30%) and stir at 150° C. for 30 min, add 0.1 g deionized water for hydrolysis reaction at 120° C. for 15 hr, and then vacuumize to remove water and shift to crystallization at 200° C. for 24 hr. Wash the obtained mixture with 200 g absolute alcohol by centrifugation for three times, and obtain nano-SiO.sub.2 powder after intensive drying and crushing, with the size of 12 nm.

Embodiment 31

(86) Use of Caprolactam as Solvent for Synthesis of Nano-SiO.sub.2 by Sol-Gel Method

(87) Add 6 g tetraethyl orthosilicate into 100 g molten caprolactam (purity of caprolactam ≧60%, moisture ≦30%) and stir at 150° C. for 30 min, add 40 g deionized water for hydrolysis reaction at 120° C. for 5 hr, and then vacuumize to remove water and shift to crystallization at 200° C. for 24 hr. Wash the obtained mixture with 200 g absolute alcohol by centrifugation for three times, and obtain nano-SiO.sub.2 powder after intensive drying and crushing, with the size of 80 nm.

Embodiment 32

(88) Use of Caprolactam as Solvent for Synthesis of Nano-TiO.sub.2 by Sol-Gel Method

(89) Add 5 ml butyl titanate into 100 g molten caprolactam (purity of caprolactam ≧99.5%, moisture ≦0.1%) and stir at 80° C. for 30 min, add 5 g deionized water for hydrolysis reaction at 100° C. for 24 hr, and then vacuumize to remove water and shift to crystallization at 200° C. for 18 hr. Wash the obtained mixture with 200 g absolute alcohol by centrifugation for three times, and obtain nano-TiO.sub.2 powder after intensive drying and crushing FIG. 23 is TEM image of synthetic nano-TiO.sub.2 powder with the method in this Embodiment, and the observation results show that the product is composed of particles of about 7 nm in diameter.

Embodiment 33

(90) Use of Caprolactam as Solvent for Synthesis of Nano-Fe.sub.3O.sub.4 by High-Temperature Pyrolysis

(91) Add 3.2 g carbonyl iron into 100 g molten caprolactam (purity of caprolactam ≧99.5%, moisture ≦0.1%) and stir at 150° C. for 30 min to make it fully dissolved, add 5 g glucose, and increase the temperature to 270° C. for reflux reaction for 2 hr. Wash the obtained mixture with 200 g absolute alcohol by centrifugation for three times, and obtain nano-Fe.sub.3O.sub.4 powder after intensive drying and crushing, with the size of 4 nm and the saturation magnetization of 65 emu/g.

Embodiment 34

(92) Use of Caprolactam as Solvent for Synthesis of Nano-ZnS by High-Temperature Pyrolysis

(93) Add 2.2 g zinc acetate and 2.4 g tetramethylthiuram disulfide (donor of anion S.sup.2−) into 100 g molten caprolactam (purity of caprolactam ≧90%, moisture ≦1%) and stir at 150° C. for 30 min to make it fully dissolved, and increase the temperature to 270° C. for reflux reaction for 2 hr. Wash the obtained mixture with 200 g absolute alcohol by centrifugation for three times, and obtain nano-ZnS powder after intensive drying and crushing.

Embodiment 35

(94) Use of Caprolactam as Solvent for Synthesis of Nano-TiO.sub.2 by High-Temperature Pyrolysis

(95) Add 1 g TiCl.sub.4 and 1.4 g trioctylphosphine oxide (donor of anion O.sup.2−) into 100 g molten caprolactam (purity of caprolactam ≧99.5%, moisture ≦0.01%) and stir at 80° C. for 30 min to make them fully dissolved, and increase the temperature to 270° C. for reflux reaction for 2 hr. Wash the obtained mixture with 200 g absolute alcohol by centrifugation for three times, and obtain nano-TiO.sub.2 powder after intensive drying and crushing.

Embodiment 36

(96) Use of Caprolactam as Solvent for Synthesis of Nano-Ag by High-Temperature Pyrolysis

(97) Add 4.24 g AgNO.sub.3 into 100 g molten caprolactam (purity of caprolactam ≧99.5%, moisture ≦0.01%) and stir at 80° C. for 30 min to make AgNO.sub.3 fully dissolved, add 5 g glucose, and increase the temperature to 200° C. for reaction for 12 hr. Wash the obtained mixture with 200 g absolute alcohol by centrifugation for three times, and obtain nano-Ag powder after intensive drying and crushing.

(98) The above descriptions of the embodiments are to help ordinary technicians in this technical field understand and apply this invention. The technicians skilled in the field can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the embodiments herein, and the improvement and modifications within the scope of this invention made by the technicians in this field according to the disclosure of this invention should be within the protection scope of this invention.