Wavelength‐Selective Photopolymerization of Hybrid Acrylate‐Oxetane Liquid Crystals

Abstract

We report on the wavelength‐selective photopolymerization of a hybrid acrylate‐oxetane cholesteric liquid crystal monomer mixture. By controlling the sequence and rate of the orthogonal free‐radical and cationic photopolymerization reactions, it is possible to control the degree of phase separation in the resulting liquid crystal interpenetrating networks. We show that this can be used to tune the reflective color of the structurally colored coatings produced. Conversely, the structural color can be used to monitor the degree of phase separation. Our new photopolymerization procedure allows for structuring liquid crystal networks in three dimensions, which has great potential for fabricating liquid crystal polymer materials with programmable functional properties.

Modeling the competition between phase separation and polymerization under explicit polydispersity

“…1,2 PIPS has several advantages over traditional phase separation processes, such as the ability to control the morphology of the resulting materials; cylindrical, 3,4 lamellar [5][6][7] and globular structures [8][9][10] can be realized as the evolution of morphology and its final morphology of the system are determined by competition and balance between the polymerization kinetics and the dynamics of phase separation. PIPS occurs in a variety of systems including polymeric blends, solutions, or colloidal suspensions via thermal [11][12][13][14] or photochemical initiation, [15][16][17][18] and is often used in the manufacture of polymer-based materials, such as membranes, [19][20][21] functional coatings, 22,23 and composites(or adhesives). [24][25][26][27] Over the past several decades, PIPS has garnered considerable attention due to its versatile nature in structure and design space.…”

Light Intensity-Selective Photopolymerization and Photoisomerization for Creating Colorful Polymer-Stabilized Cholesteric Liquid Crystal Patterns

“…Structural colors based on periodic organized nanostructures have been widely found in nature, such as beetles and butterflies. , During the last few decades, artificial structurally colored materials have been prepared using colloidal crystals, − block copolymers, − or cholesteric liquid crystals (CLCs). − Polymer-stabilized CLC (PSCLC) films, − a sub-category of CLCs, are usually prepared using reactive mesogens such as acrylates, − vinyl-terminated compounds, − oxetanes, or silsesquioxanes . The structural colors originate from the selective Bragg reflection (λ = nP ; λ is the reflection wavelength; n is the average refractive index, and P is the helical pitch), which are tunable by changing the amount of chiral dopants.…”