Conductive compositions and method
View Patent ↗Conductive compositions for use with medical electrodes are provided. The conductive compositions utilize a surfactant capable of both reducing the surface tension of the conductive composition as well as increasing the viscosity of the conductive composition. Methods of preparing these conductive compositions are also provided.
1. A conductive composition comprising:
from about 15 weight % to about 50 weight % of a humectant or a mixture of humectants;
from about 18% to about 45% of a combination of monomers comprising, in polymerized form, from about 1 wt % to about 20 weight % of a first monomer, in which the first monomer comprises a mixture of an organic acid selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, trans-cinnamic acid, crotonic acid, linoleic acid, linolenic acid, maleic acid, sorbic acid, and combinations thereof, one or more salts thereof, and from about 15 weight % to about 45 weight % of a second monomer, in which the second monomer is one or more monomers of the formula CH 2 ═CHC(O)XR, in which X is O or NH and R is an unsubstituted or substituted alkyl group of from about 1 to about 5 carbon atoms;
from about 0.01 weight % to about 0.5 weight % of a surfactant selected from the group consisting of, nonylphenol ethoxylates, derivatives thereof, and combinations thereof, capable of providing the composition with a viscosity of from about 250 cps to about 40,000 cps; and
from about 0.05 weight % to about 7 weight % of a conditioning agent comprising silica.
2. The conductive composition according to claim 1 , further comprising from about 0.1% to about 8% of an electrolyte or a mixture of electrolytes.
3. The conductive composition according to claim 1 , further comprising a neutralizer selected from the group consisting of ammonium hydroxide, sodium hydroxide, potassium hydroxide, lithium hydroxide, and combinations thereof.
4. The conductive composition according to claim 1 , further comprising a cross linking agent selected from the group consisting of bis-acrylamides, methacrylamides, diethylene glycol diacrylate, diethylene glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, ethoxylated trimethylolpropane triacrylate, ethoxylated trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylates, and combinations thereof.
5. The conductive composition according to claim 1 , further comprising a polymerization initiator selected from the group consisting of 2,2-azobisisobutyronitrile, 1hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1 -phenylpropan-1-one, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propan-1 -one, 2,2-dimethoxy-2-phenylacetophenone, benzophenone, and combinations thereof.
6. The conductive composition according to claim 1 , wherein the conductive composition has a pH of from about 2 to about 6.
7. The conductive composition according to claim 1 , wherein the first monomer comprises a mixture of acrylic acid and sodium acrylate, and the second monomer comprises sodium 2-acrylamido-2-methylpropane sulfonate.
8. The conductive composition according to claim 3 , wherein the humectant is selected from the group consisting of glycerol, sorbitol, and mixtures thereof, and the neutralizer comprises sodium hydroxide.
9. The conductive composition according to claim 1 , wherein the nonylphenol ethoxylate is selected from the group consisting of nonoxynol-7 and nonoxynol-9.
10. The conductive composition according to claim 9 , wherein the nonoxynol-7 provides the composition with an effective viscosity of from about 1500 cps to about 4800 cps.
11. The conductive composition according to claim 9 , wherein the nonoxynol-9 provides the composition with an effective viscosity of from about 1200 cps to about 40,000 cps.
12. A biomedical electrode comprising:
a substrate; and
a layer of conductive composition on the substrate, the conductive composition comprising the conductive composition of claim 1 .
13. A method for forming a conductive composition, comprising the steps of:
a) preparing a monomer reaction mixture comprising:
from about 15 weight % to about 50 weight % of a humectant or a mixture of humectants;
from about 18 weight % to about 45 weight % of a combination of monomers comprising from about 1 weight % to about 20 weight % of an organic acid selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, transcinnamic acid, crotonic acid, linoleic acid, linolenic acid, maleic acid, sorbic acid, one or more salts thereof, and combinations thereof, and from about 15 weight % to about 45 weight % of the sodium salt of 2-acrylamido-2-methylpropane sulfonic acid;
from about 0.01 weight % to about 0.5 weight % of a surfactant selected from the group consisting of nonylphenol ethoxylates, derivatives thereof, and combinations thereof;
from about 0.05 weight % to about 7 weight % of a conditioning agent comprising silica; and
(b) polymerizing the monomer or combination of monomers to form a copolymer as the conductive composition having a viscosity of from about 250 cps to about 40,000 cps.
14. The method according to claim 13 , further comprising from about 0.1% to about 8% of an electrolyte or a mixture of electrolytes.
15. The method according to claim 13 , further comprising a neutralizer selected from the group consisting of ammonium hydroxide, sodium hydroxide, potassium hydroxide, lithium hydroxide, and combinations thereof.
16. The method according to claim 13 , further comprising a cross linking agent selected from the group consisting of bis-acrylamides, methacrylamides, diethylene glycol diacrylate, diethylene glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, ethoxylated trimethylolpropane triacrylate, ethoxylated trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylates, and combinations thereof.
17. The method according to claim 13 , further comprising a polymerization initiator selected from the group consisting of 2,2-azobisisobutyronitrile, 1hydroxycyclohexylphenyl ketone; 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2 -hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propan-1-one, 2,2-dimethoxy-2 -phenylacetophenone, benzophenone, and combinations thereof.
18. The method according to claim 13 , wherein the monomer reaction mixture comprises from about 20 weight % to about 30 weight % of the sodium salt of 2-acrylamido-2methylpropane sulfonic acid and about 5 weight % to 10 weight % of the acrylic acid.
19. The method according to claim 15 , wherein the humectant comprises glycerol and the neutralizer comprises sodium hydroxide.
20. The method according to claim 13 , wherein the nonylphenol ethoxylate is selected from the group consisting of nonoxynol-7 and nonoxynol-9, and wherein the conductive composition has a viscosity of from about 500 cps to about 40,000 cps.
21. The method according to claim 13 , wherein the surfactant comprises nonoxynol-9, and the composition has an effective viscosity of from about 1200 cps to about 40,000 cps.
22. A conductive composition comprising:
from about 15 weight % to about 50 weight % of glycerol;
from about 18% to about 45% of a combination of monomers comprising, in polymerized form, from about 1 weight % to about 20 weight % of a first monomer comprising an organic acid selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, trans-cinnamic acid, crotonic acid, linoleic acid, linolenic acid, maleic acid, sorbic acid, one or more salts thereof, and combinations thereof, and from about 15 weight % to about 45 weight % of a second monomer, in which the second monomer is one or more monomers of the formula CH 2 ═CHC(O)XR, in which X is O or NH and R is an unsubstituted or substituted alkyl group of from about 1 to about 5 carbon atoms;
from about 0.01 weight % to about 0.5 weight % of nonoxynol-9; and
from about 0.05 weight % to about 7 weight % of silica,
wherein the combination of nonoxynol-9 and silica provides the composition with a viscosity of from about 1200 cps to about 40,000 cps.