Direct Observation of Long-Chain Branches in a Low-Density Polyethylene

The properties of a polymer change significantly depending on the structure of the polymer chain, particularly, with branched structures, depending on the number of branches and the length of the branch.* However, the long-chain branch (LCB) structure of polyethylene was unclear, due particularly to the complex polymer structure and the limitations of its analysis methods.

In their study “Direct Observation of Long-Chain Branches in a Low-Density Polyethylene” Ken-ichi Shinohara, Masahiro Yanagisawa and Yuu Makida measured the chain length of LCBs and the distance between branch points of LDPE by atomic force microscopy.*

The article mentions the use of NanoWorld Ultra-Short Cantilevers (USC) for high speed atomic force microscopy ( AFM probe type USC-F1.2-k0.15 ) for the single-molecule imaging by atomic force microscopy .*

Figure 1 from “Direct Observation of Long-Chain Branches in a Low-Density Polyethylene “ by K. Shinohara et al.: Direct measurement of LCB in a tubular LDPE (F200-0 fractionated). (A) AFM image of a single molecule of LDPE on mica in DMTS at 25 °C. X: 279 nm, Y: 209 nm, Z: 18 nm. (B) Length of each chain of LDPE. (C) A wire model of self-shrinking structure of polymer chain of LDPE. Main chain: red wire. LCB: black wire. The model was created to be one tenth of the length of the extended chain based on AFM observation (B), MD simulation (Fig. S1), and the molecular weight determined by SEC-MALLS-Visc experiments (see Fig. 2).
Figure 1 from “Direct Observation of Long-Chain Branches in a Low-Density Polyethylene “ by K. Shinohara et al.: Direct measurement of LCB in a tubular LDPE (F200-0 fractionated). (A) AFM image of a single molecule of LDPE on mica in DMTS at 25 °C. X: 279 nm, Y: 209 nm, Z: 18 nm. (B) Length of each chain of LDPE. (C) A wire model of self-shrinking structure of polymer chain of LDPE. Main chain: red wire. LCB: black wire. The model was created to be one tenth of the length of the extended chain based on AFM observation (B), MD simulation (Fig. S1), and the molecular weight determined by SEC-MALLS-Visc experiments (see Fig. 2).

*Ken-ichi Shinohara, Masahiro Yanagisawa, Yuu Makida
Direct Observation of Long-Chain Branches in a Low-Density Polyethylene
Nature Scientific Reportsvolume 9, Article number: 9791 (2019)
doi: https://doi.org/10.1038/s41598-019-46035-9

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