Method of depositing an inorganic film on an organic polymer
Inorganic materials are deposited onto organic polymers using ALD methods. Ultrathin, conformal coatings of the inorganic materials can be made in this manner. The coated organic polymers can be used as barrier materials, as nanocomposites, as catalyst supports, in semiconductor applications, in coating applications as well as in other applications.
1. A method of forming a continuous inorganic alumina film on a polymer substrate material which does not contain functional groups, and mechanically interlocking the polymer substrate material and the alumina film, comprising:
(a) contacting the polymer substrate material which does not contain functional groups with trimethyl aluminum or triethyl aluminium;
(b) at a temperature below the temperature at which the polymer substrate material degrades, melts or softens enough to lose its physical shape, allowing the trimethyl aluminum or triethyl aluminum to diffuse into the polymer chain network of the polymer substrate material, without previously performing a precursor reaction to introduce functional groups onto the surface of the polymer substrate material, wherein the polymer substrate material is selected from low density polyethylene, linear low density polyethylene, substantially linear polyethylene, polypropylene, and polystyrene;
(c) allowing the trimethyl aluminium or triethyl aluminium to be absorbed by the polymer chain network;
(d) at a temperature below the temperature at which the polymer substrate material degrades, melts or softens enough to lose its physical shape, contacting the polymer substrate material surface with a gas-phase wetting reactant which reacts with the trimethyl aluminum or triethyl aluminum absorbed by the polymer chain network in step c, to form discontinuous inorganic deposits of alumina within the polymer chain network; and
(e) repeating a reaction cycle comprising steps (a), (b), (c), and (d) until the mass of the polymer substrate material and alumina film increases linearly, evidencing that the discontinuous inorganic deposits of alumina have grown and interconnected to form a diffusion barrier comprising a continuous inorganic alumina film mechanically interlocked to the organic polymer substrate material, wherein steps (a)-(e) are performed at a temperature below 550K.
2. The method of claim 1 , wherein the polymer substrate material is in the form of a film.
3. The method of claim 1 , wherein the polymer substrate material is in the form of a particulate.
4. The method of claim 3 , wherein the method is conducted by fluidizing a bed of the particulate polymer substrate material.
5. The method of claim 1 , wherein an additional inorganic material is deposited over the continuous inorganic alumina film.
6. The method of claim 1 , wherein the continuous alumina film is ultrathin and conformal.
7. The method of claim 6 , wherein the continuous alumina film has a thickness of from 0.5 nanometer to 200 nanometers.
8. The process of claim 1 , wherein the continuous inorganic alumina film formed in step e forms a diffusion barrier which prevents further penetration of the gas-phase wetting reactant into the polymer substrate material.
9. The process of claim 8 , wherein, after step e, additional inorganic material is deposited onto the diffusion barrier formed by the continuous inorganic alumina film at the surface of the polymer substrate material by conducting a sequence of at least two self-limiting reactions via an atomic layer deposition process and at a temperature below 550K to deposit the inorganic material onto the surface of said polymer substrate material.