Use of Low-Temperature Thermal Alkylation to Eliminate Ink Migration in Microcontact Printed Patterns

• Published in: Chemistry : a European journal 2002-12, Vol.8 (23), p.5363-5367
• Main Authors: Brandow, Susan L., Schull, Terence L., Martin, Brett D., Guerin, Daniel C., Dressick, Walter J.
• Format: Article
• Language: English
• Subjects: alkylation; hydrogel; imprinting; metallization; microcontact printing
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/1521-3765(20021202)8:23<5363::AID-CHEM5363>3.0.CO;2-6

We demonstrate aqueous hydrogel‐based microcontact printing of amine ligands into solvent‐templated nanocavities of chloromethylphenyl‐based siloxane or thin polymer films. Migration of pyridine ligands within films following printing, which can compromise pattern fidelity, is eliminated by heat treatment of the substrate. Gentle heating (e.g., 50 °C, 5 min) leads to the efficient alkylation of mobile pyridine adsorbate by the CCl bonds of the film, covalently tethering the adsorbate to the surface as a pyridinium salt. Subsequent binding of a Pd‐based colloid to surface pyridinium (and remaining strongly bound and immobile pyridine ligand) sites permits selective electroless metal deposition and fabrication of patterned metal films. Efficient microcontact printing of pyridine ink from aqueous hydrogel stamps into solvent templated nanocavities in chloromethylphenylsiloxane films, with subsequent selective electroless metal deposition, is described. The formation of pyridinium species in the film by thermal alkylation, as shown here in the N (1s) XPS spectrum, prevents ink migration after printing and preserves pattern fidelity during metallization.