論文 / 著書情報
Article / Book Information
題目(和文)

動的光重合法の開発と二次元分子配向パターン形成

Title(English)

Development of a scanning wave photopolymerization method andinscription of two-dimensional molecular alignment patterns

著者(和文)

久野恭平

Author(English)

Kyohei Hisano

出典(和文)

学位:博士(工学),学位授与機関:東京工業大学,
報告番号:甲第10857号,授与年月日:2018年3月26日,
学位の種別:課程博士,
審査員:宍戸 厚,穐田 宗隆,山元 公寿,西山 伸宏,田巻 孝敬

Citation(English)

Degree:Doctor (Engineering),
Conferring organization: Tokyo Institute of Technology,
Report number:甲第10857号,
Conferred date:2018/3/26,
Degree Type:Course doctor,Examiner:,,,,

学位種別(和文)

博士論文

Category(English)

Doctoral Thesis

種別(和文)

要約

Type(English)

OutlinePowered by T2R2 (Tokyo Institute Research Repository)

The purpose of this study is to develop a new dye-free optical method for
macroscopically, two-dimensionally (2D) aligning LCs in polymeric systems. The
author proposed a concept of scanning wave photopolymerization (SWaP) using
spatiotemporal scanning of light that triggers a mass flow as the polymerization reaction
propagates, generating arbitrary LC alignment coincident with the incident light patterns.
In Chapter 2, a serendipitous discovery for achieving the concept of SWaP wasproposed. A simple photopolymerization through a photomask with non-polarized lightand no alignment layer resulted in generating uniform one-dimensional (1D) due to 1D
molecular diffusion along the normal vector to the edge line of the irradiated region. The
existence of diffusion was evident by analyzing surface structure of the resultant
polymer film. Furthermore, the photopolymerization through a patterned photomask
realized the generation of 2D radial molecular alignment with a resolution of 2 µm.
In Chapter 3, the author explored to generate alignment patterns over large areas.
As a first transition step and for ease of characterization, 1D scanning of slit light during
photopolymerization was investigated. Optical measurements such as polarized optical
microscopy, polarized ultraviolet-visible (UV-vis) spectroscopy, and polarized infrared
spectroscopy revealed that the resultant film had macroscopic, in-plane 1D alignment ofboth LC units and polymer main chains along the light scanning direction. Furthermore,
the author achieved a macroscopic 1D alignment in a wide variety of chemical systems
with various combinations of monomers, crosslinkers and photoinitiators.
In Chapter 4, the author proposed the mechanism that SWaP generated adiffusion-triggered mass flow enabling to align molecules. For proving this, a test
system was designed. In the system, diffusion was caused simply by contacting two
different mixtures injected into a glass cell from separate sides where one included amonomer and a photoinitiator, and the other additionally included a well-definedpolymer. After a certain duration, the cell was normally irradiated with UV light causing
uniform polymerization and fixing any generated alignment. The polymerized film
exhibited 1D molecular alignment around the contacted region. The alignment length
had good agreement with that of theoretically estimated from Fick’s law of diffusion.
This means that the driving force aligning molecules is a diffusion-triggered mass flow.
In Chapter 5, the author developed optical setups using a digital light processor
for achieving SWaP with a mask-free spatiotemporally scanned light, and inscribed
representative 2D alignment patterns over large areas in a single step: radial alignment,
azimuthal alignment, in-plane helical alignment, and spay-bent alignment along the lightscanning direction. Furthermore, optical functionality of the films was evaluated byusing appropriate light sources. The author confirmed that films had the ability to
manifest unique optical functionalities that have never been reported previously.
In this study, the author proposed a simple photopolymerization method, termed
SWaP, enabling one to inscribe arbitrary 2D alignment patterns over large areas without
for any extra steps, with the potential resolution down to light diffraction limit merely
by spatiotemporally scanning the actinic light. It is noteworthy that SWaP can beapplicable in a wide variety of chemical systems because the alignment was triggeredby a simple mass flow arising from molecular diffusion, evident from experimental andtheoretical results. Furthermore, the author achieved to design and develop new photonic
applications with unique optical properties that could not be achieved by using
conventional photoalignment methods. The author believes that SWaP provides a new,general, and powerful pathway as a chemical system platform for the simple creation ofa variety of high-performance LC devices such as photonic materials.