Method of producing nano-scaled inorganic platelets
View Patent ↗The present invention provides a method of exfoliating a layered material (e.g., transition metal dichalcogenide) to produce nano-scaled platelets having a thickness smaller than 100 nm, typically smaller than 10 nm. The method comprises (a) dispersing particles of a non-graphite laminar compound in a liquid medium containing therein a surfactant or dispersing agent to obtain a stable suspension or slurry; and (b) exposing the suspension or slurry to ultrasonic waves at an energy level for a sufficient length of time to produce separated nano-scaled platelets. The nano-scaled platelets are candidate reinforcement fillers for polymer nanocomposites.
1. A method of exfoliating a layered material to produce separated nano-scaled platelets having a thickness smaller than 100 nm, said method comprising:
a) dispersing particles of a layered material in a liquid medium containing therein a surfactant or dispersing agent to produce a suspension or slurry, wherein said layered material is selected from a transition metal dichalcogenide, MoS 2 , TaS 2 , WS 2 , MoSe 2 , TaSe 2 , WSe 2 , or a combination thereof and said layered material has never been subjected to intercalation; and
b) exposing said suspension or slurry to ultrasonication at an energy level for a sufficient length of time to produce said separated nano-scaled platelets.
2. The method of claim 1 wherein said ultrasonication step is conducted at a temperature lower than 100° C.
3. The method of claim 1 wherein said energy level is greater than 80 watts.
4. The method of claim 1 wherein said ultrasonication step is followed by a mechanical shearing treatment selected from air milling, ball milling, rotating blade shearing, or a combination thereof.
5. The method of claim 1 wherein said liquid medium comprises water, organic solvent, alcohol, a monomer, an oligomer, or a resin.
6. The method of claim 1 wherein said platelets comprise single-layer or double-layer platelets.
7. The method of claim 1 wherein said surfactant or dispersing agent is selected from the group consisting of anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, silicone surfactants, fluoro-surfactants, polymeric surfactants, sodium hexametaphosphate, sodium lignosulphonate, poly (sodium 4-styrene sulfonate), sodium dodecylsulfate, sodium sulfate, sodium phosphate, sodium sulfonate, and combinations thereof.