Polymer Morphological Change Induced by Terahertz Irradiation

September 22, 2019

Title

Polymer Morphological Change Induced by Terahertz Irradiation

Author

Hiromichi Hoshina, Hal Suzuki, Chiko Otani, Masaya Nagai, Keigo Kawase, Akinori Irizawa & Goro Isoyama

Year

2016

Journal

Scientific Reports

Abstract

As terahertz (THz) frequencies correspond to those of the intermolecular vibrational modes in a polymer, intense THz wave irradiation affects the macromolecular polymorph, which determines the polymer properties and functions. THz photon energy is quite low compared to the covalent bond energy; therefore, conformational changes can be induced “softly,” without damaging the chemical structures. Here, we irradiate a poly(3-hydroxybutylate) (PHB) / chloroform solution during solvent casting crystallization using a THz wave generated by a free electron laser (FEL). Morphological observation shows the formation of micrometer-sized crystals in response to the THz wave irradiation. Further, a 10−20% increase in crystallinity is observed through analysis of the infrared (IR) absorption spectra. The peak power density of the irradiating THz wave is 40 MW/cm2, which is significantly lower than the typical laser intensities used for material manipulation. We demonstrate for the first time that the THz wave effectively induces the intermolecular rearrangement of polymer macromolecules.

Instrument

IRT-7200

Keywords

FTIR microscopy, Terahertz, polymer, morphology