SWELLING INDUCED DEFORMATION OF SUPPORTED POLYMER NANOLINES

Vijay R. Tirumala,¹ Christopher Stafford,¹ Rui Huang,² Leonidas Ocola³

¹Polymers Division, National Institute of Standards and Technology, Gaithersburg MD

²Department of Mechanical and Aerospace Engineering, University of Texas, Austin TX

³Center for Nanoscale Materials, Argonne National Laboratory, Argonne IL

Abstract

The swelling behavior of isolated polymer nanolines supported on a rigid substrate is studied to quantitatively establish the parameters governing the mechanical reliability of polymer nanostructures. In the range of 50-250 nm linewidths, we show that the swollen lines undergo Euler buckling with stable higher order modes due to the constraint for expansion at the polymer-substrate interface. The critical wavelength for buckling non-intuitively increases with decreasing line length. The uniaxial swelling strain is thus a function of the initial length and decreases dramatically as the line length approaches twice the buckling wavelength for infinitely long lines. A critical length, larger than the buckling wavelength for infinitely long features, exists below which the lines remain mechanically stable regardless of their crosslink density. For sufficiently long lines of width (50 to 250) nm widths and height-to-width aspect-ratios in the range 0.5-1.7, the scaling relationship for buckling wavelength vs. linewidth suggests that swelling remains reasonably isotropic.

Name: Vijay R. Tirumala

Mentor’s name: Wen-li Wu

Division: Polymers (854)

Laboratory: Materials Science and Engineering

Room and Building: A323, Bldg. 224

Mail Stop: 8541

Telephone: (301) 975 6840

FAX: (301) 975 3928

E-mail: vijay.tirumala@nist.gov

Sigma Xi member: Yes

Category: Materials