Frictional anisotropy and sectorization in poly(4-methyl-1-pentene) lamellar crystals studied by lateral force microscopy

Lateral force microscopy (LFM) measurements are performed on solution-grown lamellar crystals of isotactic poly(4-methyl-1-pentene). Fold-domain boundaries are observed to protrude above the surface of the crystals. Within the fold domains the magnitude of the friction signal at a given load was found to depend on the scan direction. Frictional anisotropy is exhibited and is shown to be independent of topography. The observed friction anisotropy is discussed in terms of the structure of the fold surface and ascribed to the presence of an ordered arrangement of folds.