Abstract
| - A novel approach is presented for manipulating the size and chemistry of nanoscopic featuresusing a combination of contact molding and living free radical polymerization. In this approach a highlycross-linked photopolymer, based on a methacrylate/acrylate mixture, was patterned into submicrometer-sized features on a silicon wafer using a contact-molding technique. A critical component of the monomermixture was the incorporation of an initiator containing monomer into the network structure, which providessites for functional group amplification. Features ranging in size from 5 μm to <60 nm were accuratelyreplicated by this process and living free radical polymerizations, both atom transfer radical and nitroxide-mediated polymerization (NMP), could be conducted from these initiating sites to yield polymer brusheswhich represent a grafted layer of linear chains attached to the original network polymer. Grafts consistingof polystyrene, poly(methyl methacrylate), and poly(2-hydroxyethyl)methacrylate were grown with controlledthicknesses ranging from 10 to 143 nm and graft molecular weights of between 18 000 to 290 000 amu.As a result of this secondary graft process, feature sizes could be tuned from the original 100 nm down to20 nm, and the surface chemistry varied from hydrophilic to hydrophobic starting from the same initialmaster pattern. The thin films and patterned features were characterized by contact angle, ellipsometry,optical, and atomic force microscopies.
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