Emily M Weiss, 4640 Locke St UNIT 621, Haverhill, MA 01830

2010023, Sep 16, 2010

Oct 18, 2007

12/311811

Michal Lahav - Rehovot, IL
Adam Winkleman - Brookline MA, US
Max Narovlyansky - Cambridge MA, US
Emily A. Weiss - Cambridge MA, US
Leonard N.J. Rodriguez - Cambridge MA, US
George M. Whitesides - Newton MA, US

President and Fellows of Harvard College - Cambridge MA

B01J 41/12
B32B 3/00
B05D 3/06
G03F 7/20

428156, 521 30, 427595, 430322

In one aspect, methods of patterning of thin films of an ionotropic polymer (e.g., poly(acrylic acid)) are provided. These processes can create micron or sub-micron-scale patterns of ionotropic polymers such as cation crosslinked poly(acrylic acid) (CCL-PAA). In one embodiment, patterning may be performed within microfluidic channels by flowing a solution of crosslinking agent (e.g., metal cations such as Ag, Ca, Pd, Al, La, and Ti) that can crosslink a portion of an ionotropic polymer in contact with the solution. In another embodiment, methods of patterning ionotropic polymers involve photolithography. Upon patterning a positive photoresist (e.g., diazonaphthoquinone-novolac resin) on a film of CCL-PAA, the exposed regions of CCL-PAA can be etched by an aqueous solution. Advantageously, the patterned, crosslinked polymer may also serve as both a reactant and a matrix for subsequent chemistry. For example, in some embodiments, the initial crosslinking cation can be exchanged for a second cation that could not be patterned photolithographically. Patterned films of CCL-PAA can also be used to host and template the reduction of metallic cations to metallic nanoparticles, and to fabricate porous, low-k dielectric substrates.