Polymer Morphological Change Induced by Terahertz Irradiation.
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/cm(2), 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.
Terahertz Sensing and Imaging Research Team, RIKEN, 519-1399 Aramaki-Aoba, Aoba-ku, Sendai, Miyagi, 980-0845, Japan.
Hiromichi
H
Hoshina
Terahertz Sensing and Imaging Research Team, RIKEN, 519-1399 Aramaki-Aoba, Aoba-ku, Sendai, Miyagi, 980-0845, Japan.
Hal
H
Suzuki
Terahertz Sensing and Imaging Research Team, RIKEN, 519-1399 Aramaki-Aoba, Aoba-ku, Sendai, Miyagi, 980-0845, Japan.
Chiko
C
Otani
Graduate School of Engineer Science, Osaka University, 1-3 Machikaneyama, Toyonaka 560-8531, Japan.
Masaya
M
Nagai
Institute of Scientific and Industrial Research (ISIR), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka, 567-0047, Japan.
Keigo
K
Kawase
Institute of Scientific and Industrial Research (ISIR), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka, 567-0047, Japan.
Akinori
A
Irizawa
Institute of Scientific and Industrial Research (ISIR), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka, 567-0047, Japan.
Goro
G
Isoyama