Chapter 22
Cooperative Molecular Alignment
Process Enabled by Scanning Wave
Photopolymerization
Atsushi Shishido, Yoshiaki Kobayashi, Norihisa Akamatsu, Kyohei Hisano,
and Miho Aizawa
Abstract Arbitrary and precise control of two-dimensional (2D) molecular alignment patterns over large areas play an important role for developing highly functionalized soft materials and devices. Here we demonstrate a dye-free system for 2D
alignment patterning, termed “scanning wave photopolymerization (SWaP)”. SWaP
utilizes a spatial light-triggered mass flow induced by scanning light to propagate the
wavefront to direct molecular order. Macroscopic, arbitrary 2D alignment patterns
are generated in a wide variety of optically transparent polymer films from various
polymerizable mesogens with sufficiently high birefringence (>0.1) by single-step
photopolymerization, without alignment layers or polarized light sources. SWaP
successfully inscribed a set of 500 × 300 arrays of a radial alignment pattern with a
size of 27.4 μm × 27.4 μm, in which each individual pattern is smaller by a factor
of 10
4 than that achievable by conventional photoalignment methods.
Keywords Molecular alignment · Scanning wave photopolymerization · Liquid
crystal · Unpolarized light · Photoalignment
22.1 Introduction
Macroscopic alignment control of liquid crystal (LC) films is key to developing nextgeneration highly functionalized photonic, electronic, mechanical and biomedical
organic devices [1–5]. Current methods achieve the large-area alignment of LCs
which compose self-assembled hierarchical parallel or perpendicular ordering over
various length scales from nanometer to micrometer [6–9]. Such methods use uniform
external fields such as elongation, surface rubbing treatment, and electromagnetic
or light fields [10–12]. Among these methods, elongation is the most simple and
A. Shishido (B) · Y. Kobayashi · N. Akamatsu · K. Hisano · M. Aizawa
Laboratory for Chemistry and Life Science, Institute of Innovative Research,
Tokyo Institute of Technology, Midori-ku, Yokohama 226-8503, Japan
e-mail: ashishid@res.titech.ac.jp
A. Shishido · Y. Kobayashi · N. Akamatsu
Department of Chemical Science and Engineering, School of Materials and Chemical
Technology, Tokyo Institute of Technology, Midori-ku, Yokohama 226-8503, Japan
© Springer Nature Singapore Pte Ltd. 2020
H. Miyasaka et al. (eds.), Photosynergetic Responses in Molecules
and Molecular Aggregates, https://doi.org/10.1007/978-981-15-5451-3_22
375
Cooperative Molecular Alignment
Process Enabled by Scanning Wave
Photopolymerization
Atsushi Shishido, Yoshiaki Kobayashi, Norihisa Akamatsu, Kyohei Hisano,
and Miho Aizawa
Abstract Arbitrary and precise control of two-dimensional (2D) molecular alignment patterns over large areas play an important role for developing highly functionalized soft materials and devices. Here we demonstrate a dye-free system for 2D
alignment patterning, termed “scanning wave photopolymerization (SWaP)”. SWaP
utilizes a spatial light-triggered mass flow induced by scanning light to propagate the
wavefront to direct molecular order. Macroscopic, arbitrary 2D alignment patterns
are generated in a wide variety of optically transparent polymer films from various
polymerizable mesogens with sufficiently high birefringence (>0.1) by single-step
photopolymerization, without alignment layers or polarized light sources. SWaP
successfully inscribed a set of 500 × 300 arrays of a radial alignment pattern with a
size of 27.4 μm × 27.4 μm, in which each individual pattern is smaller by a factor
of 10
4 than that achievable by conventional photoalignment methods.
Keywords Molecular alignment · Scanning wave photopolymerization · Liquid
crystal · Unpolarized light · Photoalignment
22.1 Introduction
Macroscopic alignment control of liquid crystal (LC) films is key to developing nextgeneration highly functionalized photonic, electronic, mechanical and biomedical
organic devices [1–5]. Current methods achieve the large-area alignment of LCs
which compose self-assembled hierarchical parallel or perpendicular ordering over
various length scales from nanometer to micrometer [6–9]. Such methods use uniform
external fields such as elongation, surface rubbing treatment, and electromagnetic
or light fields [10–12]. Among these methods, elongation is the most simple and
A. Shishido (B) · Y. Kobayashi · N. Akamatsu · K. Hisano · M. Aizawa
Laboratory for Chemistry and Life Science, Institute of Innovative Research,
Tokyo Institute of Technology, Midori-ku, Yokohama 226-8503, Japan
e-mail: ashishid@res.titech.ac.jp
A. Shishido · Y. Kobayashi · N. Akamatsu
Department of Chemical Science and Engineering, School of Materials and Chemical
Technology, Tokyo Institute of Technology, Midori-ku, Yokohama 226-8503, Japan
© Springer Nature Singapore Pte Ltd. 2020
H. Miyasaka et al. (eds.), Photosynergetic Responses in Molecules
and Molecular Aggregates, https://doi.org/10.1007/978-981-15-5451-3_22
375