SOFT-CHEMISTRY PRODUCTION OF NEW NANOSTRUCTURED HYBRID FILMS FROM COLLOIDAL SOLUTIONS OF POLYSACCHARIDE AND SOLUBLE METAL ALKOXIDES

Abstract

A method includes producing transparent and mechanically stable hybrid films from a colloidal solution containing one or more biopolymers, one or more soluble metal precursors each including at least two to four hydrolysable alkoxide type functions M(OR).sub.n (n=2, 3 or 4), one or more solvents and optionally a catalyst and a stabiliser.

Claims

1. A method comprising producing transparent and mechanically stable hybrid films from a colloidal solution containing one or more biopolymers, one or more soluble metal precursors each comprising at least two to four hydrolysable alkoxide type functions M(OR). (n=2, 3 or 4), one or more solvents and optionally a catalyst and a stabiliser.

2. The method according to claim 1, wherein the colloidal solution is prepared using a coordinating species that is a bio-polymer of chitosan, chitin, cellulose, alginate, carrageenan, starch type, or a mixture of two or more components, perfectly soluble in the solvent(s) used of which one is necessarily water.

3. The method according to claim 2, wherein a growing species for producing the hybrid film is the one or more soluble metal precursor soluble in its parent alcohol and comprising between two and four alkoxide functions M(OR).sub.n (n=2, 3 or 4), of which the central metal is of Si, Ti, Zr, Zn, Fe, Al, Ge, Sn, V type, a mixture of two precursors or a mixture of several precursors.

4. The method according to claim 3, wherein the silicon alkoxide used comprises between 1 hydrolysable silicon atom (in the case of tetraethoxysilane) up to 30 hydrolysable silicon atoms, in the case of polymethylethyltriethoxysilylsiloxane.

5. The method according to claim 4, wherein a spacer between two silicon atoms is a flexible unit of methyl, ethyl, propyl, pentyl, hexyl, heptyl, decyl nature or rigid of aryl, biphenyl, pyrene, naphthyl type.

6. The method according to claim 3, wherein the growing species in the solution of bio-polymer contains at least one single chelating function of atrane, acetylacetonate, carboxylic acid, phosphonate type to delay polymerisation.

7. The method according to claim 3, wherein the growing species is a mixture of metal alkoxides M(OR).sub.4 without organic groups (with MSi, Ti, Zr, Zn, Fe, Al, Ge, Sn, V) and a second bis- or tris-organoalkoxysilane of (RO).sub.3SiRSi(OR).sub.3 type of which the spacer is of methyl, ethyl, propyl, pentyl, hexyl, heptyl, decyl nature or rigid of aryl, biphenyl, pyrene, naphthyl type.

8. The method according to claim 3, wherein the growing species is a mixture of metal alkoxides M(OR).sub.4 without organic groups (with MSi, Ti, Zr, Zn, Fe, Al, Ge, Sn, V) and a source of hydrolysable silicon of polymethylethyltriethoxysilylsiloxane type of which the chain length varies between 5 and 30.

9. The method according to claim 2, wherein the growing species generates a perovskite of BaTiO.sub.3-x(OR).sub.x, SrTiO.sub.3-x(OR).sub.x, PDMS-SiO.sub.2-x(OR).sub.xBaTiO.sub.3-y(OR).sub.y and PDMS-SiO.sub.2-x(OR).sub.xSrTiO.sub.3-y(OR).sub.y type.

10. The method according to claim 1, comprising performing a densification of the oxo-alkoxy-metal oxide-polysaccharide network between 25 and 100 C., in a mixture of solvents.

11. The method according to claim 10, wherein the mixture of solvents include water: ethanol, water: isopropanol, water: butanol, water: THF, water: toluene, water: heptane, water: acetonitrile, water: DMSO; or lwater: DMF

Description

BRIEF DESCRIPTION OF THE FIGURES

[0016] FIG. 1. Illustration of the different existing technologies for the preparation of nanostructured films (a-c) and the technology that is the subject matter of the present invention (d).

[0017] FIG. 2. Diagram showing certain polysaccharides: chitin, chitosan, cellulose, alginates, carrageenan.

[0018] Table 1. Table describing the combinations having made it possible to access nanostructured films of chitosan-metal alkoxide type.

[0019] FIG. 3. Diagram showing the alkoxysilanes used.

[0020] Table 2. Table describing the combinations having made it possible to access nanostructured films of chitosan-alkoxysilane type.

[0021] Table 3. Table describing the combinations having made it possible to access nanostructured films of alginate-metal alkoxide type.

[0022] FIG. 4. Schematic diagram of the growth by sol-gel process of a metal alkoxide in a colloidal solution of chitosan.

[0023] FIG. 5. Schematic diagram of the growth by sol-gel process of a metal alkoxide in a colloidal solution of alginate.

[0024] FIG. 6. Scanning electron microscopy and EDX analyses.

[0025] EXAMPLE OF PREPARATION OF NANOSTRUCTURED FILMS

Chitosan-Oxo-Alkoxy-Titanium Oxide

[0026] To an acidified aqueous solution of chitosan (50 mg, 0.29 mmolNH.sub.2) in 4 mL of wateracetic acid 1% (v/v) is added directly drop by drop titanium II diisopropoxy-bis-acetylacetonate (76 mg, 0.21 mmol). The mixture is maintained under stirring for 1 hour at room temperature (25 C.). After, the resulting solution is placed in a petri dish, and exposed to air for 24 hours to enable the evaporation of the solvent. A homogenous film of slightly yellowish white colour and of a mass m=86 mg was able to be obtained.

Chitosan-Silica

[0027] To an acidified aqueous solution of chitosan (50 mg, 0.29 mmolNH.sub.2) in 4 mL of wateracetic acid 1% (v/v) is added directly tetraethoxysilane (60 mg, 0.29 mmol). The mixture is maintained under stirring for 1 hour at room temperature (25 C.). Next, the solution obtained is placed in a petri dish, and exposed to air for 24 hours to enable the evaporation of the solvent. A colourless film, transparent and homogenous, of a mass m=56 mg was able to be obtained.

Chitosan-Oxo-Alkoxy-Vanadium Oxide

[0028] To an acidified aqueous solution of chitosan (100 mg, 0.58 mmolNH.sub.2) in 4 mL of wateracetic acid 1% (v/v) is added oxytriisopropoxy vanadium (V) (103 mg, 0.42 mmol). The mixture is maintained under stirring for 4 days at room temperature (25 C.). After, the resulting solution is placed in a petri dish, and exposed to air for 24 hours to enable the evaporation of the solvent. A homogenous film of yellow colour and of a mass m=98 mg was able to be obtained.

Chitosan-Oxo-Alkoxy-Tin Oxide

[0029] To an acidified aqueous solution of chitosan (50 mg, 0.29 mmolNH.sub.2) in 4 mL of wateracetic acid 1% (v/v) is added tetraisopropoxy tin (IV) (103 mg, 0.29 mmol). The mixture is maintained under stirring for 1 hour at room temperature (25 C.). After, the resulting solution is placed in a petri dish, and exposed to air for 24 hours to enable the evaporation of the solvent. A colourless film, transparent and homogenous, and of a mass m=54 mg was able to be obtained.

Chitosan-Oxo-Alkoxy-Germanium Oxide

[0030] To an acidified aqueous solution of chitosan (100 mg, 0.58 mmolNH.sub.2) in 4 mL of wateracetic acid 1% (v/v) is added tetraethoxy germanium (IV) (147 mg, 0.58 mmol). The mixture is maintained under stirring for 1 hour at room temperature (25 C.). After, the resulting solution is placed in a petri dish, and exposed to air for 24 hours to enable the evaporation of the solvent. A homogenous film of white colour and of a mass m=153 mg was able to be obtained.

Chitosan-Oxo-Alkoxy-Zinc Oxide

[0031] To an acidified aqueous solution of chitosan (50 mg, 0.29 mmolNH.sub.2) in 4 mL of wateracetic acid 1% (v/v) is added zinc acetate (25 mg, 0.145 mmol). The mixture is maintained under stirring for 1 hour at room temperature (25 C.). After, the resulting solution is placed in a petri dish, and exposed to air for 24 hours to enable the evaporation of the solvent. A colourless film, transparent, and of a mass m=68 mg was able to be obtained.

Chitosan-Oxo-Alkoxy-Iron Oxide

[0032] To an acidified aqueous solution of chitosan (50 mg, 0.29 mmolNH.sub.2) in 4 mL of wateracetic acid 1% (v/v) is added a solution of iron (III) acetylacetonate (50 mg, 0.145 mmol) in 5 mL of wateracetic acid 1% (v/v). The mixture is maintained under stirring for 1 hour at room temperature (25 C.). After, the resulting solution is placed in a petri dish, and exposed to air for 24 hours to enable the evaporation of the solvent. A homogenous film of rusty colour and of a mass m=82 mg was able to be obtained.

Chitosan-Oxo-Alkoxy-Aluminium Oxide

[0033] To an acidified aqueous solution of chitosan (50 mg, 0.29 mmolNH.sub.2) in 4 mL of wateracetic acid 1% (v/v) is added aluminium triisopropoxide (60 mg, 0.29 mmol). The mixture is maintained under stirring for 1.5 h at room temperature (25 C.). After, the resulting solution is placed in a petri dish, and exposed to air for 24 hours to enable the evaporation of the solvent. A colourless film, transparent and homogenous, and of a mass m=56.5 mg was able to be obtained.

Chitosan-Oxo-Alkoxy-Zirconium Oxide

[0034] To an acidified aqueous solution of chitosan (50 mg, 0.29 mmolNH.sub.2) in 4 mL of wateracetic acid 1% (v/v) is added a solution of zirconium tetrabutoxide (137 mg, 0.29 mmol) in 1 mL of ethanol. The mixture is maintained under stirring for 5 hours at room temperature (25 C.). After, the resulting solution is placed in a petri dish, and exposed to air for 24 hours to enable the evaporation of the solvent. A slightly milky film and of a mass m=103 mg was able to be obtained.

Chitosan-Oxo-Alkoxy-Titanium Oxide-Oxo-Alkoxy-Silicon Oxide

[0035] To a mixture of titanium bis (acetylacetonate) diisopropoxide (106 mg, 0.29 mmol) and TEOS (60 mg, 0.29 mmol) in 1 mL of ethanol is added an acidified aqueous solution of chitosan (50 mg, 0.29 mmolNH.sub.2) in 4 mL of wateracetic acid 1% (v/v). The mixture is maintained under stirring for 1 hour at room temperature (25 C.). After, the resulting solution is placed in a petri dish, and exposed to air for 24 hours to enable the evaporation of the solvent. A homogenous film of slightly orangey colour and of a mass m=92.7 mg was able to be obtained.

Chitosan-Oxo-Alkoxy-Zirconium Oxide-Oxo-Alkoxy-Silicon Oxide

[0036] To a mixture of zirconium tetrabutoxide (137 mg, 0.29 mmol) and TEOS (60 mg, 0.29 mmol) in 1 mL of ethanol is added an acidified aqueous solution of chitosan (50 mg, 0.29 mmolNH.sub.2) in 4 mL of wateracetic acid 1% (v/v).The mixture is maintained under stirring for 1.5 h at room temperature (25 C.). After, the resulting solution is placed in a petri dish, and exposed to air for 24 hours to enable the evaporation of the solvent. A homogenous film of milky colour and of a mass m=97.9 mg was able to be obtained.

Chitosan-Oxo-Alkoxy-Titanium Oxide-Oxo-Alkoxy-Silicon Oxide-Oxo-Alkoxy-Vanadium Oxide

[0037] To a mixture of vanadium (III) acetylacetonate (50 mg, 0.145 mmol), titanium diisopropoxy-bis-(acetylacetonate) (53 mg, 0.145 mmol) and TEOS (30 mg, 0.145 mmol) in 1 mL of ethanol is added an acidified aqueous solution of chitosan (50 mg, 0.29 mmolNH.sub.2) in 4 mL of wateracetic acid 1% (v/v). The mixture is maintained under stirring for 2 hours at room temperature (25 C.). After, the resulting solution is placed in a petri dish, and exposed to air for 24 hours to enable the evaporation of the solvent. A homogenous film of green-olive colour and of a mass m=116 mg was able to be obtained.

Chitosan-BaTiO.SUB.3

[0038] To a mixture of barium isopropoxide (74 mg, 0.29 mmol) and titanium diisopropoxy-bis-acetylacetonate (106 mg, 0.29 mmol) in 1 mL of ethanol is added an acidified aqueous solution of chitosan (50 mg, 0.29 mmolNH.sub.2) in 4 mL of wateracetic acid 1% (v/v). The mixture is maintained under stirring for 1 hour at room temperature (25 C.). After, the resulting solution is placed in a petri dish, and exposed to air for 24 hours to enable the evaporation of the solvent. A homogenous film of orange yellow colour and of a mass m=107 mg was able to be obtained.