Electrically-conductive, pressure-sensitive adhesive and biomedical electrodes

An electrically-conductive, pressure-sensitive adhesive formed by the free radical copolymerization of an adhesive precursor comprising:

• a carboxylic acid as a water-soluble hydrogen bond donating monomer;
• N-vinyl pyrrolidone as a water-soluble hydrogen bond accepting monomer;
• a free radical initiator;
• and
• a plasticizing, electrically-conductive solution comprised of from about 0 to 98% by weight water-soluble, polar organic compound, from about 2 to 100% by weight water, and from about 0 to 12% by weight soluble salt;
• wherein the ratio of hydrogen bond accepting sites to hydrogen bond donating sites on the monomers is from about 1:3 to about 6:1, the weight ratio of carboxylic acid to N-vinyl pyrrolidone is from about 1:2 to about 3:1, the adhesive precursor contains from about 12% to about 50% by weight total monomers, the acid sites on the hydrogen bond donating monomer are from about 5% to about 80% neutralized, and the composition is substantially homogeneous and pressure-sensitive adhesive.

A process for making an electrically-conductive, pressure-sensitive adhesive comprising:

• (a) providing an adhesive precursor comprising a carboxylic acid as a hydrogen bond donating monomer, N-vinyl pyrrolidone as a hydrogen bond accepting monomer, a free radical initiator, and a plasticizing, electrically-conductive solution comprised of from about 0 to 98% by weight water-soluble organic compound, from about 2 to 100% by weight water, and from about 0 to 12% by weight soluble salt;
• wherein the ratio of hydrogen bond accepting sites to hydrogen bond donating sites on the monomers is from about 1:3 to about 6:1, the weight ratio of carboxylic acid to N-vinyl pyrrolidone is from about 1:2 to about 3:1, the adhesive precursor contains from about 12% to about 50% by weight of total monomers, the hydrogen bond donating sites on the hydrogen bond donating monomer are from about 5% to about 80% neutralized, and the composition is substantially homogeneous and pressure-sensitive adhesive;
• (b) coating the adhesive precursor on a substrate;
• and
• (c) initiating copolymerization of the monomers in the adhesive precursor.

A method of making a biomedical electrode comprising:

• (a) providing a web of conductor;
• (b) covering the conductor with an electrically-conductive, pressure-sensitive adhesive comprised of a conformable, cohesive, adhesive copolymer formed by free radical polymerizing an adhesive precursor comprising a carboxylic acid as a water-soluble hydrogen bond donating monomer, N-vinyl pyrrolidone as a water-soluble hydrogen bond accepting monomer, and a polymerization initiator, wherein the molar ratio of hydrogen bond accepting sites to hydrogen bond donating sites available on the monomers is from about 1:3 to about 6:1 and wherein the weight ratio of carboxylic acid to N-vinyl pyrrolidone is from about 1:2 to about 3:1, and a plasticizing, electrically-conductive solution comprised of from about 0 to 98% by weight water-soluble, polar organic compound, about 2 to 100% by weight water, and about 0 to 12% by weight water-soluble salt;
• wherein the electrically-conductive, pressure-sensitive adhesive contains from about 12% to about 50% by weight non-volatile copolymer matrix, the hydrogen bond donating sites on the copolymer matrix are from about 5% to about 80% neutralized, and the composition is substantially homogeneous and pressure-sensitive adhesive;
• and
• (c) cutting the laminate of steps a and b to form electrodes.