GRADIENT GLASS-LIKE CERAMIC STRUCTURES AND BOTTOM-UP FABRICATION METHOD THEREOF
Thin glass-like ceramic films which possess organic or physically functional structures with thicknesses in the 15 to 500 nm range and bottom-up methods for their fabrication are described. SiO 2 -rich structures having gradient properties are formed from a silsesquioxane having an electronegative β substituent and at least one organofunctional silane or at least one metal alkoxide.
1 . A SiO 2 -rich structure having gradient properties, wherein the structure is formed from a silsesquioxane having an electronegative β substituent and at least one organofunctional silane.
2 . The SiO 2 -rich structure according to claim 1 , wherein the structure has gradient hydrophobicity/hydrophilicity properties.
3 . The SiO 2 -rich structure according to claim 1 , wherein the silsesquioxane has a halogen, ether, or carboxylate functional group in the β position.
4 . The SiO 2 -rich structure according to claim 3 , wherein the silsesquioxane is 2-acetoxyethylsilsesquioxane.
5 . The SiO 2 -rich structure according to claim 1 , wherein the at least one organofunctional silane is a dialkyldialkoxysilane or an alkyltrialkoxysilane.
6 . The SiO 2 -rich structure according to claim 5 , wherein the at least one organofunctional silane is a dialkyldimethoxysilane or a dialkyldiethoxysilane.
7 . The SiO 2 -rich structure according to claim 5 , wherein the at least one organofunctional silane is an alkyltrimethoxysilane or an alkyltriethoxysilane.
8 . The SiO 2 -rich structure according to claim 5 , wherein the at least one organofunctional silane is methoxy(polyethyleneoxy)propyltrimethoxysilane or isobutyltriethoxysilane.
9 . The SiO 2 -rich structure according to claim 1 , wherein the structure is formed from 2-acetoxyethylsilsesquioxane, methoxy(polyethyleneoxy)propyltrimethoxysilane, and isobutyltriethoxysilane.
10 . A SiO 2 -rich structure having a gradient concentration of at least one metal oxide selected from the group consisting of oxides of germanium, tantalum, titanium, zirconium and hafnium, wherein the structure is formed from a metal alkoxide having the same metal as the at least one metal oxide and a silsesquioxane having an electronegative β substituent, wherein a plurality of silicon atoms are each bonded to four oxygen atoms and no more than about 50% of the silicon atoms are bonded to carbon atoms.
11 . The SiO 2 -rich structure according to claim 10 , wherein the SiO 2 -rich structure has a gradient refractive index.
12 . The SiO 2 -rich structure according to claim 1 , wherein a plurality of silicon atoms are each bonded to four oxygen atoms and no more than about 50% of the silicon atoms are bonded to carbon atoms.
13 . The SiO 2 -rich structure according to claim 1 , wherein the structure is a ceramic film.
14 . The SiO 2 -rich structure according to claim 13 , wherein the ceramic film has a thickness of about 15 to about 500 nm.
15 . A method for forming a SiO 2 -rich structure having a gradient property, the method comprising preparing a coating composition comprising a silsesquioxane having an electronegative β substituent, at least one organofunctional silane, and optionally a solvent, coating the mixture onto a substrate, and heating and/or UV irradiating the coated substrate.
16 . The method according to claim 15 , wherein the coating composition comprises a volatile polar solvent.
17 . The method according to claim 15 , wherein the coating comprises spin-on deposition, 3-D printing, microcontact printing, or direct writing.
18 . The method according to claim 15 , wherein the heating and/or UV irradiating is performed in an atmosphere containing at least about 0.5% relative humidity.
19 . The method according to claim 15 , wherein the heating is performed at about 150° C. to about 700° C.
20 . The method according to claim 15 , wherein the coating step comprises adjusting relative flow rates of the at least one organofunctional silane.
21 . The method according to claim 15 , wherein the coating composition comprises varying amounts of the at least one organofunctional silane.
22 . A method for forming a SiO 2 -rich structure having a gradient property, the method comprising preparing a coating composition comprising a silsesquioxane having an electronegative β substituent, at least one metal alkoxide, and optionally a solvent, coating the mixture onto a substrate, and heating and/or UV irradiating the coated substrate.
23 . The method according to claim 22 , wherein the metal alkoxide is selected from the group consisting of germanium isopropoxide, tantalum ethoxide, titanium n-butoxide, zirconium n-propoxide, and hafnium n-butoxide.
24 . The method according to claim 22 , wherein the SiO 2 -rich structure has a gradient refractive index.
25 . The method according to claim 22 , wherein the SiO 2 -rich structure has a gradient metal oxide concentration.
26 . The method according to claim 22 , wherein the coating step comprises adjusting relative flow rates of the at least one metal alkoxide.
27 . The method according to claim 22 , wherein the coating composition comprises varying amounts of the at least one metal alkoxide.