Patterning Thin Films of Poly(ethylene imine) on a Reactive SAM Using Microcontact Printing

Abstract

This paper describes the patterning of poly(ethylene imine) (PEI) on a surface into structures having submicron edge resolution. This procedure consists of three steps: (1) formation of a reactive self-assembled monolayer (SAM) terminating in interchain carboxylic anhydride groups on gold and silver; (2) patterning of this SAM by microcontact printing (μCP) using a poly(dimethylsiloxane) (PDMS) stamp inked with PEI (this polymer contains primary and secondary amines that are reactive toward the anhydride groups); (3) hydrolysis of the unreacted anhydride groups with base and removal of noncovalently bound PEI. The patterned thin films of PEI are attached covalently to the SAM by amide bonds. The pendant, unreacted primary and secondary amines of the attached PEI can be used as reactive nucleophilic groups in further steps of chemical modification. This type of postmodification has been illustrated by allowing the amine groups of the covalently attached PEI to react with perfluorooctanoyl chloride, palmitoyl chloride, palmitic anhydride, and poly(styrene-alt-maleic anhydride). The PEI films and their derivatives were characterized using atomic force microscopy (AFM), scanning electron microscopy (SEM), polarized infrared external reflectance spectroscopy (PIERS), contact angles of water, and X-ray photoelectron spectroscopy (XPS).

Replacing −CH2CH2– with −CONH– Does Not Significantly Change Rates of Charge Transport through AgTS-SAM//Ga2O3/EGaIn Junctions

“…The most important problem in the design of compounds 1-3 is the long -(CH 2 ) [10][11] chain connecting the thiol and the amide group. This length limits the size of the groups, R, that can be placed on the other side of the amide, since for large R groups, values of J(V) become too small to measure reliably with our electrometer.…”

Patterned Orientations of Liquid Crystals on Affinity Microcontact Printed Proteins

“…Printed Proteins** By Matthew L. Tingey, Edward J. Snodgrass, and Nicholas L. Abbott* In the 11 years since Whitesides and co-workers demonstrated microcontact printing to be a broadly useful method for patterning surfaces with organized monolayers of alkanethiols, [1,2] this method and other closely related ªsoft lithographicº techniques [3] have been extended to the patterning of colloids, [4] metal complexes, [5] polymers, [6,7] proteins, [5,8] and metal ions. [9] In its simplest form, microcontact printing comprises the ªinkingº of the surface of a poly(dimethylsiloxane) (PDMS) stamp with a solution of the species to be patterned, and conformal contact of the inked stamp with a second surface.…”

Exploring the Feasibility of Fabricating Micron-Scale Components Using Microcontact Printing LDRD Final Report

“…In order to get the hydrophilic solution of ligands to wet the surface of the hydrophobic PDMS stamp, they oxidized the stamp by exposing it to plasma in air for one minute. The plasma treatment oxidizes the Si-CH 3 groups and generates Si-OH groups [32].…”

“…Yan et al [32] covalently attached thin films of polyethylene imine to reactive alkanethiolate SAMs on gold and silver using microcontact printing. They exposed a PDMS stamp to oxygen plasma (10-second exposure at 0.2 Torr) to make the surface hydrophilic prior to inking.…”