Free standing metal-ion doped thin films
The present disclosure provides a thin film self-assembled from polymer(s), where the thin film includes a metal ion so it can further undergo ion exchange to incorporate an ion or blend of ions. Methods for making these thin films, subsequently top coating them so they can be freed from their original substrate, and methods of using these thin films are also disclosed.
1 . A method for depositing a film on a hydrophobic silicone substrate, the method comprising:
(a) depositing a first deposition solution comprising at least one positively charged polymer, wherein the pH of the solution is at or above the pK a of the at least one positively charged polymer and wherein the first deposition occurs for about 8 seconds to about 30 seconds to form a first layer of said first deposition material;
(b) applying a rinse solution to remove any excess unbound polymer from the first deposition solution, allowing it to reside on the surface for a period of time t rinse of about 8-90 seconds;
(c) removing excess rinse solution using a diffusion barrier removal step whereby a layer of rinse solution of 2-5 microns is left on the positively charged polymer layer;
(d) depositing a second deposition solution comprising at least one negatively charged polymer, wherein the pH of the solution is at or above the pK a of the at least one negatively charged polymer, the second deposition solution contains a counterion for the at least one negatively charged polymer, wherein the counterion is provided by one or more of calcium nitrate, aluminum nitrate, copper chloride, magnesium chloride, manganese chloride, sodium chloride, calcium chloride, potassium chloride, copper sulfate, magnesium sulfate, sodium acetate, calcium acetate, sodium carbonate, potassium carbonate, calcium carbonate, or manganese carbonate, and wherein the second deposition occurs for about 8 seconds to about 30 seconds to form a second layer of said second deposition material;
(e) applying a rinse solution to remove any excess unbound negatively charged polymer from the second deposition solution, allowing it to reside on the surface for a period of time t rinse of about 8-90 seconds;
(f) removing excess rinse solution using a diffusion barrier removal step whereby a layer of rinse solution of 2-5 microns is left on a second layer made from the second deposition material;
(g) exposing the the second layer to a metal ion solution for a period of about 45 seconds to 3 minutes, whereby the counterion is exchanged for a metal ion from the metal ion solution;
(h) applying a first rinse solution to remove any unbound excess metal ions for a period of time t rinse equal to about 45 seconds to about 3 minutes;
(i) applying a reducing solution to the the second layer of the second deposition solution for a period of about 45 sec to 3 minutes;
(j) applying a second rinse solution for a period of time t rinse equal to about 45 seconds to about 3 minutes; and
(k) drying to form a completed film.
2 . The method of claim 1 , wherein the metal ion replacing the counterion is selected from gallium ion, cerium ion, or silver ion.
3 . The method of claim 1 , wherein steps g-j are repeated for up to about five (5) cycles, prior to step (e).
4 . The method of claim 2 , wherein the metal ion solution comprises silver nitrate having a concentration between about 1 mM to about 10 mM.
5 . The method of claim 1 , wherein the reducing solution comprises sodium borohydride having a reductive potential between about −300 mV and about −500 mV.
6 . The method of claim 1 , wherein the completed film comprises dimensions that are at least one foot wide and at least three feet in length.
7 . The method of claim 3 , further comprising depositing a third deposition solution comprising a hydrophilic polymer and substantially drying it to form a layer of the hydrophilic polymer less than 5 mil (125 micron) thick.
8 . The method of claim 7 , wherein the hydrophilic polymer is a generally regarded as safe hydrophilic polymer.
9 . The method of claim 7 , wherein the hydrophilic polymer is a polyvinyl alcohol.
10 . The method of claim 7 , further comprising blending an additive into the solution of hydrophilic polymer so that the additive incorporates into the completed film.
11 . The method of claim 10 , wherein the additive is an antibiotic, a salicylic acid, a hydroquinone, a retinoid, a hyaluronic acid, or a vitamin C.
12 . The method of claim 1 , wherein steps a-f are repeated for up to 50 cycles, prior to step g.
13 . The method of claim 1 , wherein the at least one positively charged polymer achieves its charge from some combination of primary amine, secondary amine, tertiary amines, imine, amido, or amine or is selected from poly(allylamine hydrochloride) (PAH), poly-lysine (PLL), linear or branched poly(ethylene imine) (PEI), poly(histidine), poly(N,N-dimethyl aminoacrylate), poly(N,N,N-trimethylaminoacrylate chloride), poly(methyacrylamidopropyltrimethyl ammonium chloride), and chitosan.
14 . The method of claim 13 , wherein the one positively charged polymer is poly(allylamine hydrochloride) (PAH).
15 . The method of claim 1 , wherein the at least one negatively charged polymer is selected from poly(acrylic acid) (PAA), alginate, hyaluronic acid, heparin, heparin sulfate, chondroitin sulfate, dextran sulfate, poly(methacrylic acid), oxidized cellulose, carboxymethyl cellulose, polyaspartic acid, and polyglutamic acid.
16 . The method of claim 15 , wherein the one negatively charged polymer is poly(acrylic acid) (PAA).
17 . The method of claim 1 , wherein the second deposition solution comprises calcium nitrate.