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Photochromic Materials by Postpolymerisation Surface Modification
摘要： Photochromic materials are available by a postpolymerization surface modi?cation of diverse polymers in a multistep sequential process mediated, ?rst, by carbene insertion chemistry, second, by diazonium coupling with a tethered precursor, and ?nally by coupling to a spiropyran. This three-step sequence is e?cient, and surface loading densities of 1013 molecules cm?2 are typically achievable, leading to materials with observable photochromic and wettability behavior, which operate over multiple cycles without signi?cant photobleaching or loss of e?cacy. Materials suitable for application in this process include both reactive, but also lower surface energy polymers. Although the process is particularly e?cient for high surface area materials, surface modi?cation onto lower surface area substrates, while being intrinsically less e?cient, is nonetheless su?ciently e?ective that changes in macroscopic photochromic properties are readily observable.
关键词： wettability behavior,carbene insertion chemistry,Photochromic materials,postpolymerization surface modi?cation,spiropyran,diazonium coupling
更新于2025-09-10 09:29:36
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Photoactive Functional Soft Materials (Preparation, Properties, and Applications) || Photochemical Chirality Induction and Inversion in Soft Materials
摘要： Chirality or “handedness” is a prerequisite of the biological world, where life exists in a specific chirality. In living organisms, almost all the sugars are exclusively right‐handed (d‐isomer), amino acids are left‐handed (l‐isomer), and DNA coils assemble into right‐handed helices. The reason behind this homochirality is still an unresolved issue. Inspired by the natural homochirality, the scientific community has been interested in exploring the mechanism of transmission of chirality from the molecular level of monomeric units to the macro‐ or supramolecular level, as well as the origin of chirality. The supramolecular chirality in nature from self‐assembled achiral molecules and its specific handedness play a crucial role in the evolution of life and the development of supramolecular materials. While the chirality of molecules is of configurational and conformational origin, supramolecular level chirality arises from the organization of molecules, with formation of a chiral superstructure by means of long‐range positional and orientational orders of molecules.
关键词： Supramolecular,Polymers,Circularly Polarized Light,Photochromic Switches,Helical Structures,Liquid Crystals,Photochemical,Self-Assembly,Soft Materials,Chirality
更新于2025-09-09 09:28:46
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Investigation of Structure and Dynamics in a Photochromic Molecular Crystal by NMR Crystallography
摘要： A photochromic anil, N-(3,5-di-t-butylsalicylidene)-4-amino-pyridine, has been studied by single-crystal X-ray diffraction, multinuclear magic-angle spinning NMR and first-principles density functional theory (DFT) calculations. Interpretation of the solid-state NMR data on the basis of calculated chemical shifts confirms the structure is primarily composed of molecules in the ground-state enol tautomer, while thermally-activated cis-keto and photoisomerised trans-keto states exist as low-level defects with populations that are too low to detect experimentally. Variable temperature 13C NMR data reveals evidence for solid-state dynamics which is found to be associated with fast rotational motion of t-butyl groups and 180° flips of the pyridine ring, contrasting the time-averaged structure obtained by X-ray diffraction. Comparison of calculated chemical shifts for the full crystal structure and an isolated molecule also reveals evidence for an intermolecular hydrogen-bond involving the pyridine ring and an adjacent imine carbon which facilitates the flipping motion. The DFT calculations also reveal that the molecular conformation in the crystal structure is very close to the energetic minimum for an isolated molecule, indicating that the ring dynamics arise as a result of considerable steric freedom of the pyridine ring and which also allows the molecule to adopt a favourable conformation for photochromism.
关键词： NMR crystallography,photochromic,anil,solid-state NMR,DFT calculations,molecular dynamics
更新于2025-09-09 09:28:46
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Comparison of Intraocular Straylight in Patients with Clear and Photochromic Intraocular Lenses
摘要： Purpose: To compare visual acuity and intraocular straylight after implantation of clear and photochromic intraocular lenses (IOLs) in a mesopic lighting condition. Methods: Clear IOLs were implanted in 95 eyes of 72 patients (clear IOL group), and photochromic IOLs were implanted in 22 eyes of 16 patients (photochromic IOL group). Best-corrected visual acuity (BCVA) was measured indoors before surgery and 1 month after surgery. Straylight values were measured indoors before surgery and 1 and 2 months after surgery using the C-quant straylight meter (Oculus GmbH, Wetzlar, Germany). Results: There were no significant differences between the 2 groups in BCVA at 1 month postoperatively (p = 0.587). Mean straylight values of clear and photochromic IOL groups were 2.76 ± 1.89 log (s) and 2.88 ± 2.04 log (s) preoperatively, 1.39 ± 0.84 log (s) and 1.32 ± 0.26 log (s) at 1 month postoperatively, and 1.43 ± 0.92 log (s) and 1.45 ± 0.50 log (s) at 2 months postoperatively. There were no significant differences between the 2 groups in indoor straylight values (p = 0.778, 0.709, 0.929, before surgery, 1 and 2 months after surgery respectively). Repeated-measure analysis of straylight values also showed no significant difference between the 2 groups (p > 0.05). Conclusions: There were no significant differences in BCVA and straylight values between clear and photochromic IOL groups under a mesopic light condition. Therefore, photochromic IOL could be suitable choice for cataract patients who spend significant time under mesopic conditions.
关键词： C-quant,Photochromic intraocular lens,Blue light,Straylight,Mesopic
更新于2025-09-09 09:28:46
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Reversible Photodoping of TiO <sub/>2</sub> Nanoparticles for Photochromic Applications
摘要： Observations on the strong photochromic effect of crystalline TiO2 quantum dots (mean size ≈ 4 nm) are presented. The synthesized quantum dots consist of irregularly shaped anatase TiO2 nanoparticles (NPs) and are dispersed in butanol (8% by mass). Obtained NPs exhibit a dramatic photoresponse to UV light, enabling effective transmittance modulation in a broad wavelength range extending from the visible to near-infrared region, and even the thermal black body radiation regime beyond 10 μm. The exceptional photoresponse is attributed to hole-scavenging by butanol, TiO2 self-reduction, injection of electrons to the conduction band, and consequent localized surface plasmon resonances in NPs. The observed optical effect is reversible, and the initial high transmittance state can be restored simply by exposing the NPs to air. The applied NP synthesis route is economic and can be easily scaled for applications such as smart window technologies.
关键词： UV light,TiO2 nanoparticles,localized surface plasmon resonances,transmittance modulation,photochromic
更新于2025-09-04 15:30:14
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Color Build-Up and UV-protection Performance of Encapsulated Photochromic Dye-Treated Cotton Fabrics
摘要： A spirooxazine-based photochromic dye was encapsulated by an oil-in-water emulsion, solvent evaporation method. The encapsulated dye was applied to cotton fabric by a pad-cure process with different binder types. Ultraviolet (UV) protection was increased with application of the encapsulated photochromic dye. The type of binder used affected the photochromic color build-up during UV irradiation and could modify the UV protection imparted by the encapsulated photochromic dyes on textiles.
关键词： UV Protection,Binders,Photochromic Dyes,Encapsulation,Color
更新于2025-09-04 15:30:14
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Flexible photochromic cellulose triacetate based bionanocomposites modified with sol-gel synthesized V2O5 nanoparticles
摘要： Transparent and flexible bionanocomposites with photochromic properties based on cellulose triacetate (CTA) and sol-gel synthesized V2O5 nanoparticles were prepared. Poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (EPE) triblock copolymer was added to achieve nanostructured materials and simultaneously control the dispersion of synthesized V2O5 nanoparticles. Investigated bionanocomposites were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), atomic force microscopy (AFM), tensile tests, and UV-Vis spectroscopy. FTIR results confirmed the presence of hydrogen bonds in the bionanocomposites. The miscibility between components improved with the increase of sol-gel content resulting in a decrease of the Tg and Tm of CTA phase as indicated by DSC results. Addition of EPE triblock copolymer enhanced the photochromic properties of bionanocomposites reducing the time of recovery to the initial state after 5 min of UV light irradiation. The biocompatibility of pure CTA and EPE/CTA blends as well as the photochromic properties provided by synthesized V2O5 nanoparticles make their transparent and flexible bionanocomposites ideal for possible future applications.
关键词： vanadium oxide,cellulose triacetate,photochromic properties,bionanocomposites,sol-gel
更新于2025-09-04 15:30:14