Differences in Intermolecular Interactions and Flexibility between Poly(ethylene terephthalate) and Poly(butylene terephthalate) Studied by Far-Infrared/Terahertz and Low-Frequency Raman Spectroscopy

• DOI: 10.1021/acs.macromol.0c02049
• Publication Date: 2021-01-10T18:24:07Z
• Authors: Yumiko Yamamoto; Hiromichi Hoshina; Harumi Sato
• Keywords: 02 engineering and technology; 0210 nano-technology

Herein, differences in the intermolecular interactions and flexibility between poly(ethylene terephthalate) (PET) poly(butylene (PBT) are studied by far-infrared, terahertz (THz), low-frequency Raman spectroscopy quantum chemical calculations (QCCs). Interatomic distance based on reported crystal structures natural bond orbital analysis indicate that PBT exhibits hydrogen bonding a C═O group CH2 adjacent molecular chains, while PET does not have such bonding. The results of infrared measurements also suggest groups involved Both show THz band at around 113 cm–1 111 cm–1. These bands different thermal behaviors PBT. QCCs performed using Cartesian coordinate tensor transfer method these include bending mode, those only small contribution from corresponding mode. behavior vibrational modes can be possibly attributed to difference due number groups. In addition, seem reflect C═O···H–C Therefore, it may concluded causes chains existence or non-existence It is worth noting clearly reveal flexibility. very likely both affect crystallization rate