Polymer, Vol.54, No.3, 1130-1135, 2013
Flocculated carbon nanotube composites for solvent resistant soft templated microfeatures
The swelling of a commercial thiol-ene adhesive and surfactant dispersed single wall carbon nanotubes (swCNTs) nanocomposites is investigated in a variety of organic solvents. These nanocomposites can be used to form well-defined microstructures via soft lithography. swCNTs are flocculated in suspension using a novel surfactant based on poly(fluorooxetane-block-polyethylene oxide-block-fluorooxetane); this procedure yields a loose floc, where the hydrophobic end blocks effectively create inter-tube bridges to provide a swCNT network structure in the thiol-ene prior to curing. Microfeatures (0.5 mu m posts) fabricated in the thiol-ene and its composite using soft templating demonstrate similar fidelity in the pattern transfer. A significant decrease in the swelling by organic solvents occurs upon the incorporation of swCNTs (183%-1.6% for toluene at 1 wt%). Both mechanical reinforcement by the swCNT network and reduced swelling results in stable microfeatures after exposure to toluene for 24 h, while the neat cured thiol-ene microstructure is significantly deformed. These nanocomposites appear promising alternatives to glass for enabling organic syntheses in microfluidic devices due to their structural integrity when exposed to solvents. (C) 2012 Elsevier Ltd. All rights reserved.