Direct Imaging of Polyethylene Films at Single-Chain Resolution with Torsional Tapping Atomic Force Microscopy

Abstract

The physical properties of semicrystalline polymers depend on the organisation of chains within the crystal and amorphous regions, on the interface between the two, and on the location and nature of defects. Here, torsional tapping atomic force microscopy has been used to image crystalline lamellae and the crystal-amorphous-region interface at the single-chain level with resolution down to 3.7 Å. Defects within the crystalline phase, such as buried folds and chain ends, are revealed. Imaging at the chain level also allows direct measurement of crystalline stem lengths, providing a potential route to test theories of crystal thickness selection.

Single electron states in polyethylene

“…This lamella structure is in agreement with the morphology recently observed using torsional-tapping-atomic-force microscopy. 22 A broad melting curve was observed centred around 390 K, in reasonable agreement with the experimental reported melting temperature (398 K) observed in lamellae phases of blends of branched and linear PE.…”

Molecular Conformation at the Crystal–Amorphous Interface in Polyethylene

“…2,9 Samples were prepared from a 1 wt % solution of polyethylene (M w = 84 500 Da, M w /M n = 1.28, PSS) in p-xylene (puriss. p.a.…”

Using the dissipation mode in high resolution atomic force microscopy

“…Figure 1 presents measurement data for cholesterol stearate molecules. In the lateral resolution, the obtained val ues are as good as the best results achieved by ampli tude [2,4] and frequency [3] modulation. However, the dissipation mode has an advantage-it is much easier to tune the optimum scanning parameters in this mode.…”

“…AFM ensures a very high (atomic) resolution when working in vacuum and in liquid [1]. When scanning in air, the lateral resolu tion is worse; the best results were shown in several works [2][3][4] where the molecular resolution was obtained. At the same time, it is in the air medium where the overwhelming majority of AFM measure ments are carried out.…”

“…Molecular resolution in air was demonstrated in [2,4] but it still remains a rather dif ficult problem. The fact is that the Q factor of the can tilever in air is significantly lower than in vacuum, and the surface is covered by a thin layer of adsorbed water.…”