Normal- and Reverse-Mode Thermoresponsive Controllability in Optical Attenuation of Polymer Network Liquid Crystals

Area of Science:

• Materials Science
• Polymer Chemistry
• Optics

Background:

• Photopolymerization-induced phase separation (PPIPS) is crucial for creating complex material structures.
• Controlling mesoscale domain structures in liquid crystal (LC) and reactive mesogen (RM) systems remains challenging.

Purpose of the Study:

• To develop a simple nonuniform irradiation method for PPIPS.
• To produce unconventional mesoscale domain structures with controlled LC/RM phase formation and molecular orientation.
• To investigate the formation of thermoresponsive optical-anisotropic structures.

Main Methods:

• A simple nonuniform irradiation technique was employed for photopolymerization-induced phase separation.
• Investigated LC/RM phase formation and molecular ordering based on molar ratio, curing temperature, and irradiation uniformity.
• Fabricated two distinct optical-anisotropic structures using nonuniform irradiation at varying temperatures.

Main Results:

• Successfully produced unconventional mesoscale domain structures of LC and RM phases.
• Demonstrated control over molecular orientation ordering in LC/RM systems via PPIPS.
• Achieved two types of thermoresponsive light attenuation structures (normal- and reverse-mode) through tailored irradiation and curing conditions.
• Identified specific molecular ordering (multiaxial vs. uniaxial) correlating with thermoresponse modes.

Conclusions:

• The developed nonuniform irradiation method offers precise control over mesoscale domain structures and molecular orientation.
• This approach overcomes limitations imposed by inherent material properties.
• The method is promising for creating novel optical and photonic devices, including smart windows and thermometric sheets.