Difference between revisions of "Assembly of large-area, highly ordered, crack-free inverse opal films"
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infiltration into a preassembled porous structure | infiltration into a preassembled porous structure | ||
| − | [[Image:Hatton2010 2.png|400px|thumb|left|'''Fig. 2''' Highly ordered I-<math>siO_2</math> films formed from PMMA/sol-gel coassembly (Left scale bar is <math>10\mu m </math> and right scale bar is <math>1\mu m </math>)]][[Image:Hatton2010 3.png|500px|thumb|right|'''Fig. 3''' A) | + | [[Image:Hatton2010 2.png|400px|thumb|left|'''Fig. 2''' Highly ordered I-<math>siO_2</math> films formed from PMMA/sol-gel coassembly (Left scale bar is <math>10\mu m </math> and right scale bar is <math>1\mu m </math>)]][[Image:Hatton2010 3.png|500px|thumb|right|'''Fig. 3''' A) The film thickness is directly proportional to the colloidal concentration. The threshold thickness for cracking is indicated. B) A 1.5cm I-<math>siO_2</math> film. C) A cleaved film reveals the growth direction along <110>. Inset: fcc-lattice model]] |
Cracking seems to occur along {111} planes for thin films, which is consistent with conventional evaporative deposited films, whereas thicker films seem to crack along {110} planes. | Cracking seems to occur along {111} planes for thin films, which is consistent with conventional evaporative deposited films, whereas thicker films seem to crack along {110} planes. | ||
| − | [[Image:Hatton2010 4.png|300px|thumb|right|'''Fig. 4''' ]] | + | [[Image:Hatton2010 4.png|300px|thumb|right|'''Fig. 4''' Novel <math>SiO_2</math> inverse opal structures enabled by colloidal coassembly. Schematics (left) vs. SEM images (right). (A) Synthesis of |
| + | multilayered, hierarchical films with different pore sizes by successive layer | ||
| + | deposition prior to template removal. (The top left and bottom left SEM images show the interface | ||
| + | between layers before and after calcination, respectively.) (B) <math>SiO_2</math> structures grown on topologically patterned | ||
| + | substrates (Left), SEM fractured cross section of inverse opals grown in | ||
| + | 4 μm wide, 5 μm deep channels on a Si substrate (Right). (C) Coassembly onto curved surfaces (Left), and SEM images | ||
| + | (Right) of a <math>SiO_2</math> inverse opal film layer (shown magnified, Inset) deposited | ||
| + | onto a sintered, macroporous Ti scaffold structure.]] | ||
Revision as of 02:57, 13 September 2010
Birgit Hausmann
Reference
Keywords
Coassembly, colloidal assembly, crack-free films, inverse opals, nanoporous
Overview
A new synthesis of crack-free inverse opal films over cm length scales is presented. The two step process consists of a) an evaporative deposition of polymeric colloids in a hydrolyzed silicate sol-gel precursor solution and b) a colloidal/matrix coassembly. The preferential grwoth direction is <110>. The synthesis of multilayered hierarchical films are also demonstrated. Furthermore, the inverse opal films were converted to inverse opal films of other materials as porous Si and <math>TiO_2</math> while maintaining their morphology during the gas/solid displacement reaction.
Results and Discussion
Herein we demonstrate the evaporative coassembly of a sacrificial colloidal template with a matrix material in a single step to yield a colloidal composite, thereby avoiding the need for liquid infiltration into a preassembled porous structure
Cracking seems to occur along {111} planes for thin films, which is consistent with conventional evaporative deposited films, whereas thicker films seem to crack along {110} planes.
