Method for synthesizing carbon nanotubes
A method for preparing a precursor solution for synthesis of carbon nanomaterials, where a polar solvent is added to at least one block copolymer and at least one carbohydrate compound, and the precursor solution is processed using a self-assembly process and subsequent heating to form nanoporous carbon films, porous carbon nanotubes, and porous carbon nanoparticles.
1. A method for preparing a precursor solution for synthesis of carbon nanomaterials, comprising the steps of:
adding a polar solvent to at least one block copolymer and at least one carbohydrate compound to form a precursor solution;
applying the precursor solution to a substrate;
evaporating said polar solvent to form an ordered composite film comprising separated block copolymer domains and carbohydrate compound domains; and
heating said film in an inert gas to remove the at least one block copolymer and carbonize the carbohydrate compound, thereby forming a mesoporous carbon film.
2. The method of claim 1 wherein said at least one block copolymer is selected from the group consisting of poly(butadiene-b-acrylic acid), poly(butadiene-ethylene oxide), poly(ethylene oxide-b-propylene oxide), poly(ethylene oxide-b-methacrylic acid), poly(styrene-ethylene oxide), poly(styrene-b-vinyl pyridine), polystyrene-co-poly(4-vinylpyridine) and nonionic surfactants.
3. The method of claim 2 wherein said at least one carbohydrate is selected from the group consisting of turanose, glucose, raffinose, sucrose, pentanose, starch, and cellulose.
4. The method of claim 3 wherein said polar solvent is selected from the group consisting of dimethyl formamide (DMF) solution, tetrahydrogen furan, dioxane, dimethyl sulfoxide, acetonitrile, chloroform, and cyclohexanol.
5. The method of claim 3 wherein the concentration of the at least one carbohydrate compound is between 3-10 wt %.
6. The method of claim 3 wherein the solvent is dimethyl formamide and the at least one block copolymer is polystyrene-co-poly(4-vinylpyridine).
7. The method of claim 1 wherein said substrate is selected from the group consisting of a silicon wafer, a glass slide, and gold electrodes.
8. The method of claim 1 further comprising the step of annealing said film in a solvent vapor at an elevated temperature prior to being heated in an inert gas.
9. The method of claim 8 wherein a temperature greater than 400° C. is attained when said film is heated in an inert gas.
10. The method of claim 9 wherein the concentration of the at least one carbohydrate compound is less than 5 wt %, thereby forming a lamellar mesophase film.
11. The method of claim 9 wherein the concentration of the at least one carbohydrate compound is greater than 7 wt %, thereby forming a one-dimensional hexagonal mesophase film.
12. The method of claim 8 wherein said solvent vapor comprises compound mixtures selected from the group consisting of dimethyl formamide/benzene, dimethyl formamide/tetrahydrogen furan, and dimethyl formamide/dimethyl sulfoxide.