Photopatterning Freestanding Chiral Nematic Mesoporous Organosilica Films

Abstract

Chiral nematic mesoporous organosilica (CNMO) films are functionalized with a mixture of hydrophobic silanes and spiropyran compounds to create freestanding photochromic films that can be used for reversible photo patterning. The mesoporosity and interconnected pore structure of the films imparted by the cellulose nanocrystal template enables a large crosssection of the material to be functionalized. Thus, the materials show intense absorp tion spectra from the tethered spiropyran and rapid color changes when the porous films are irradiated with UV or white light. The spiropyranbound CNMO films behave as reversible sensors where metal binding to the spi ropyran results in visible color changes detectable by the naked eye. These metals can be removed in the presence of ethanol and white light, regener ating the metalfree film. The proofofconcept demonstrated in this paper may help to develop new photochromic displays, security features, and patterns.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adfm.201703346. Results and DiscussionEt-CNMO films were synthesized according to the literature procedure [27] using 1,2-bis(trimethoxysilyl)ethane as precursor.

Nature‐Inspired Emerging Chiral Liquid Crystal Nanostructures: From Molecular Self‐Assembly to DNA Mesophase and Nanocolloids

“…2020, 32, 1801335 mesoporous organosilica films. [536,537] Compared to pure silica, such mesoporous organosilica films were found to exhibit improved flexibility and mechanical properties. The cholesteric mesoporous silica have been used as hard template to fabricate titania superstructures, where the anatase TiO 2 nanocrystals can be templated into high-surface-area mesoporous films with long-range cholesteric ordering and selective circularly polarized reflections.…”

“…The photonic reflection of such chiral nematic mesoporous silica could be modulated in a wide spectral range through changing the chirality of nanocellulose mesophases in the synthetic processes. Using the similar methodology, they also demonstrated flexible iridescent mesoporous organosilica films with a chiral nematic structure through incorporation of an ethylene bridge into the mesoporous organosilica films . Compared to pure silica, such mesoporous organosilica films were found to exhibit improved flexibility and mechanical properties.…”

Light-Controlled in Vitro Gene Delivery Using Polymer-Tethered Spiropyran as a Photoswitchable Photosensitizer

“…SP in solution, film, or nanostructures undergoes photoisomerization between a colorless ring-closed SP state and colored ring-opened merocyanine (MC) state. ,− In the present study, a trace amount of cationic polymers PSP1 or PSP2 possessing pendant SP moieties were anchored into the shell of bPEI/plasmid DNA (pDNA) complexes to form ternary polyionic nanoassemblies (Figure ). The PS activity of SPs could be turned on in the MC state and turned off in the SP state multiple times by alternating illumination with visible and UV light.…”

Tuning the Properties of Chiral Nematic Mesoporous (Organo)silica Through Thiol‐Ene Click Chemistry

“…Terpstra et al prepared CNMO materials via a post-synthetic modification path. [15] Incorporating a spiropyran compound into a pre-functionalized CNMO film with amine groups yielded CNMOs with photoswitching and tunable photopatterning properties. [15] Click reactions are simple reactions that proceed in high yield; examples include Huisgen 1,3-dipolar cycloaddition; Diels-Alder reaction; and thiol-ene and thiol-yne reactions.…”