title: Chemical patterning of ultrathin polymer films by direct-write multiphoton lithography.
abstract: We applied 2-photon laser ablation to write subdiffraction nanoscale chemical patterns into ultrathin polymer films under ambient conditions. Poly(ethylene glycol) methacrylate brush layers were prepared on quartz substrates via surface-initiated atom-transfer radical polymerization and ablated to expose the underlying substrate using the nonlinear 2-photon absorbance of a frequency-doubled Ti:sapphire femtosecond laser. Single-shot ablation thresholds of polymer films were ~1.5 times smaller than that of a quartz substrate, which allowed patterning of nanoscale features without damage to the underlying substrate. At a 1/e(2) laser spot diameter of 0.86 μm, the features of exposed substrate approached ~80 nm, well below the diffraction limit for 400 nm light. Ablated features were chemically distinct and amenable to chemical modification.
authors: Laser Thermal Laboratory, Department of Mechanical Engineering, University of California, Berkeley, California 94720, USA.
authors: Hojeong
authors: H
authors: Jeon
authors: Ray
authors: R
authors: Schmidt
authors: Jeremy E
authors: JE
authors: Barton
authors: David J
authors: DJ
authors: Hwang
authors: Lara J
authors: LJ
authors: Gamble
authors: David G
authors: DG
authors: Castner
authors: Costas P
authors: CP
authors: Grigoropoulos
authors: Kevin E
authors: KE
authors: Healy
mesh_terms: D018625:Microscopy, Atomic Force; D018613:Microscopy, Confocal; D036103:Nanotechnology; D011092:Polyethylene Glycols / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry
chemical_list: D011092:Polyethylene Glycols; D014025:Titanium