Forming patterns using thiosulfate polymer compositions
View Patent ↗A thiosulfate polymer composition includes an electron-accepting photosensitizer component, either as a separate compound or as an attachment to the thiosulfate polymer. The thiosulfate polymer composition can be applied to various articles and used to form a predetermined polymeric pattern after photothermal reaction to form crosslinked disulfide bonds, removing non-crosslinked polymer, and reaction with a disulfide-reactive material.
1. A method of forming a pattern in a polymeric composition, the method comprising:
providing a polymeric layer comprising a non-crosslinked thiosulfate polymer and an electron-accepting photosensitizer component (PS),
photochemically reacting the non-crosslinked thiosulfate polymer to provide a crosslinked polymer having disulfide groups in a predetermined pattern in the polymeric layer, leaving non-crosslinked thiosulfate polymer in area(s) of the polymeric layer outside of the predetermined pattern,
optionally washing the polymeric layer to remove the non-crosslinked thiosulfate polymer while leaving the crosslinked polymer in the predetermined pattern, and
either:
(i) treating the crosslinked polymer with a disulfide-reactive material, or
(ii) when the polymeric layer further comprises a redox active metal ion, treating the predetermined pattern with a metal ion that is capable of reacting with the redox active metal ion,
wherein the excitation energy, E PS* , of the electron-accepting photosensitizer component (PS) satisfies the following Equation 2:
E PS* ≧E R ox −E PS red Equation 2
in which E R ox represents the oxidation potential of reactant thiosulfate moiety (R) in the non-crosslinked thiosulfate polymer and E PS red represents the reduction potential of the electron-accepting photosensitizer component (PS).
2. The method of claim 1 , comprising treating the crosslinked polymer with a disulfide-reactive metal.
3. The method of claim 2 , wherein the disulfide-reactive metal is a silver, palladium, nickel, gold, or copper metal.
4. The method of claim 1 , wherein photochemically reacting of the non-crosslinked thiosulfate polymer is carried out in predetermined pattern through a mask using actinic radiation.
5. The method of claim 1 , wherein washing the polymeric layer to remove the non-crosslinked thiosulfate polymer is carried out using an aqueous solution.
6. The method of claim 1 , wherein the polymeric layer further comprises an electron-accepting photosensitizer component that is a covalently-connected component of the non-crosslinked thiosulfate polymer.
7. The method of claim 1 , wherein the non-crosslinked thiosulfate polymer is a copolymer comprising, in random order: (a) recurring units comprising thiosulfate groups, and (b) recurring units comprising an electron-accepting photosensitizer component.
8. The method of claim 7 , wherein the copolymer further comprises, in random order, (c) recurring units other than the (a) and (b) recurring units, in an amount of at least 0.1 mol %, based on the total recurring units in the copolymer.
9. The method of claim 8 , wherein the (c) recurring units comprise a pendant charged group.
10. The method of claim 8 , wherein the (c) recurring units comprise a pendant carboxy, carboxylate, phospho, phosphonate, phosphate, sulfo, sulfonate, or sulfite group.
11. The method of claim 1 , wherein the non-crosslinked thiosulfate polymer is a copolymer comprising, in random order: (a) recurring units comprising thiosulfate groups, and (c) recurring units comprising a pendant carboxy, carboxylate, phospho, phosphonate, phosphate, sulfo, sulfonate, or sulfite group, in an amount of at least 0.1 mol % and up to and including 50 mol %, based on the total recurring units in the copolymer.
12. The method of claim 11 , wherein the copolymer further comprises (d) recurring units that have a total neutral charge and are present in an amount of at least 1 mol % based on the total recurring units in the copolymer.
13. The method of claim 12 , wherein the molar ratio of the (a) recurring units to the (d) recurring units in the copolymer is from 1:3 to 3:1.
14. The method of claim 1 , wherein the polymeric layer further comprises an electron-accepting photosensitizer component in an amount of at least 0.1 mol % and up to and including 10 mol %, in relation to the molar amount of thiosulfate groups present in the polymeric layer.
15. The method of claim 1 , wherein the polymeric layer further comprises an electron-accepting photosensitizer component that is a compound separate from the non-crosslinked thio sulfate polymer.
16. The method of claim 1 , wherein the electron-accepting photosensitizer component is an organic photosensitizer N-containing heterocyclic compound, or an inorganic salt or complex.
17. The method of claim 1 , wherein the polymeric layer further comprises a redox active metal ion.
18. The method of claim 1 , wherein the polymeric layer further comprises tetraalkyl ammonium ions.
19. The method of claim 18 , wherein the non-crosslinked thiosulfate polymer is a copolymer comprising, in random order: (a) recurring units comprising thiosulfate groups, (b) recurring units comprising the electron-accepting photosensitizer component, and (c) recurring units comprising pendant charged groups.