Method of preparing an insoluble polymer film on a substrate from a soluble polymer containing labile solubilizing groups
The present invention relates to a method for preparing polymeric films, preferably electroactive films, with enhanced physical properties by the steps of applying to a substrate a solution of a polymer containing pendant labile solubilizing groups, then removing the solvent and a sufficient concentration of the labile solubilizing groups render the polymer less soluble in the solvent than before the labile groups were removed. It is believed that the removal of pendant soluble groups a) permits optimization of the semiconducting backbone for charge transport performance, b) allows direct control of microstructure in the final film, and c) renders the final film more robust during subsequent process steps needed to construct multilayer devices.
1. A method comprising the steps of
a) applying to a substrate a solution of a solvent and a polymer containing labile solubilizing groups;
b) removing the solvent from the solution to form a soluble polymer film; and
c) removing a sufficient amount of the labile solubilizing groups from the soluble polymer film or converting a sufficient amount of the labile solubilizing group to less soluble groups, to form a film on the substrate that is less soluble in the solvent than before the removal or conversion of the labile solubilizing groups,
wherein the polymer contains structural units selected from the group consisting of fluorene-2,7-diyls and triarylamine-diyls and the labile solubilizing groups contain a) a C 4 -C 30 hydrocarbyl or b) a C 3 -C 30 hydrocarbyl containing one or more heteroatoms of S, N, Si, P, or O, or c) an aralkyl group and optionally one or more heteroatoms of S, N, Si, P, or O.
2. The method of claim 1 wherein the polymer is an electroactive polymer.
3. The method of claim 1 wherein the labile groups are removed thermally, chemically, or optically, or combinations thereof.
4. The method of claim 2 wherein the polymer additionally contains structural units selected from the group consisting of 1,4-phenylenes, 1,3-phenylenes, 1,2-phenylenes, 4,4′-biphenylenes, naphthalene-1,4-diyls, naphthalene-2,6-diyls, furan-2,5-diyls, thiophene-2,5-diyls, 2,2′-bithiophene-5,5′-diyls, anthracenes-9,10-diyls, 2,1,3-benzothiadiazoles-4,7-diyls, N-substituted carbazole-3,6-diyls, N-substituted carbazole-2,7-diyls, dibenzosilole-3,6-diyls, dibenzosilole-2,7-diyls, N-substituted-phenothiazine-3,7-diyls, N-substituted-phenoxazines-3,7-diyls, dibenzothiophene-3,7-diyls, dibenzothiophene-2,8-diyls, dibenzofurane-3,7-diyls, dibenzofurane-2,8-diyls, indenofluorene-diyls, N,N,N′,N′-tetraaryl- 1,4-di-aminobenzene-diyls, N,N,N′,N′-tetraarylbenzidine-diyls, and arylsilane-diyls.
5. The method of claim 4 wherein the polymer contains structural units of a substituted fluorene-2,7-diyl as illustrated:
wherein R is a) a C 4 -C 30 hydrocarbyl or b) a C 3 -C 30 hydrocarbyl containing one or more heteroatoms of S, N, Si, P, or O, or c) an aralkyl group and optionally one or more heteroatoms of S, N, Si, P, or O; and R′ is a) H or b) a C 4 -C 30 hydrocarbyl or c) a C 3 -C 30 hydrocarbyl containing one or more heteroatoms of S, N, Si, P, or O, or d) an aralkyl group and optionally one or more heteroatoms of S, N, Si, P, or O.
6. The method of claim 5 , wherein R and R′ are each:
wherein R″ is independently H or C 1 -C 10 alkyl; and X is S or O.
7. The method of claim 6 wherein each R″ is methyl and wherein X is O.
8. The method of claim 1 wherein the polymer further contains structural units of a thiophene-2,5-diyl.
9. The method of claim 8 wherein the polymer contains structural units of a 3-C 4-20 -alkylthiophene-2,5-diyl.
10. The method of claim 5 wherein the polymer contains structural units of a triarylamine-4,4′-diyl containing labile ester groups, as illustrated:
where each R″ and each R′″ is independently alkyl or H.
11. The method of claim 10 where each R″ is methyl and each R′″ is H.
12. The method of claim 1 wherein the substrate is selected from the group consisting of paper, metals, plastics, ceramics, and semiconductors.
13. The method of claim 1 wherein the substrate is a component of an electronic device.
14. A method comprising the steps of:
a) applying to a substrate a solution of a solvent and a polymer containing labile solubilizing groups;
b) removing the solvent from the solution to form a soluble polymer film; and
c) removing a sufficient amount of the labile solubilizing groups from the soluble polymer film or converting a sufficient amount of the labile solubilizing groups to less soluble groups, to form a film on the substrate that is less soluble in the solvent than before the removal or conversion of the labile solubilizing groups,
wherein the polymer contains structural units selected from the group consisting of fluorene-2,7-diyls and triarylamine-diyls.
15. The method of claim 1 , wherein the fluorene-2,7-diyls are 9,9-disubstituted fluorenes-2,7-diyls.
16. The method of claim 1 , wherein the triarylamine-diyls are triphenylamine-4,4′-diyls, diphenyl-p-tolylamine-4,4′-diyls, or N,N-diphenylaniline-3,5-diyls.