ISSN:
1573-2711
Keywords:
lateral force microscopy
;
poly(tetrafluoroethylene)
;
frictional anisotropy
;
stick-slip motion
;
molecular imaging
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract Lateral force microscopy (LFM) studies of poly(tetrafluoroethylene) (PTFE) films with molecular resolution are reported. Thin PTFE layers with a high degree of orientation were obtained by pressing and sliding a block of polymer on a clean, heated muscovite mica substrate. LFM nanographs obtained on these films by scanning at directions between ca. 40 and 90° with respect to the film orientation direction, i.e. with respect to the direction of the polymer chains, showed a “stick-slip” type frictional motion of the LFM probe tip at the molecular level. The friction force observed at constant load decreased with decreasing scan angles. Chain-chain packing distances obtained by LFM and contact-mode atomic force microscopy were the same to within the experimental error and had a value of 5.8 Å. Dual-mode contact AFM/LFM imaging was also performed by scanning in the chain direction. Here LFM nanographs showed no distinct “stick-slip” phenomenon. The contact mode AFM images, however, exhibited clear molecular resolution with the expected chain-chain periodicity. The disappearance of the “stick” component in LFM scans performed in the chain direction was attributed to the smooth surface of PTFE on the molecular scale.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00173129
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