title: Nanometer-scale flow of molten polyethylene from a heated atomic force microscope tip.
abstract: We investigate the nanometer-scale flow of molten polyethylene from a heated atomic force microscope (AFM) cantilever tip during thermal dip-pen nanolithography (tDPN). Polymer nanostructures were written for cantilever tip temperatures and substrate temperatures controlled over the range 100-260 °C and while the tip was either moving with speed 0.5-2.0 µm s(-1) or stationary and heated for 0.1-100 s. We find that polymer flow depends on surface capillary forces and not on shear between tip and substrate. The polymer mass flow rate is sensitive to the temperature-dependent polymer viscosity. The polymer flow is governed by thermal Marangoni forces and non-equilibrium wetting dynamics caused by a solidification front within the feature.
authors.affiliation: Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Felts
authors.forename: Suhas
authors.initials: S
authors.lastname: Somnath
authors.forename: Randy H
authors.initials: RH
authors.lastname: Ewoldt
authors.forename: William P
authors.initials: WP
authors.lastname: King
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D006361:Heating / Q000295:instrumentation*; D055617:Micro-Electrical-Mechanical Systems / Q000295:instrumentation*; D018625:Microscopy, Atomic Force / Q000295:instrumentation*; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D020959:Polyethylene / Q000737:chemistry*; D012996:Solutions; D014159:Transducers; D044366:Transition Temperature
chemical_list: D012996:Solutions; D020959:Polyethylene