Molecular symmetry change of perfluoro-n-alkanes in 'Phase I' monitored by infrared spectroscopy.

ABSTRACT: Phase diagram of polytetrafluoroethylene (PTFE) comprises four regions. Phases II and IV are characterized by twisted perfluoroalkyl (R_f) chains having different twisting rate of 13/6 and 15/7, respectively, while Phase III is characterized by a planer trans-zigzag molecular skeleton like a normal alkyl chain. These are confirmed by X-ray and electron diffraction and have already been established. Unlike these, Phase I is left an unresolved matter. This phase is complicated indeed and is not symbolized by a single molecular structure. At an ambient pressure, Phase I is the temperature region above 30 ºC (303 K), and the helical molecular structure is supposed to be gradually untwisted with an elevating temperature. This untwisting image is roughly suggested by the diffraction, n

SUBMITTER: Araki T 

PROVIDER: S-EPMC11358247 | biostudies-literature | 2024 Sep

REPOSITORIES: biostudies-literature