Rewritable Color Patterns with Photochromic Diarylethene-Embedded Electrospun Fibers

Abstract

Photochromic materials have attracted much attention due to their potential for rewritable papers, memory devices, switching and sensor devices.1-19 Photochoromic materials undergo a reversible photo-induced change of a molecule between two distinct isomeric forms whose adsorption wavelengths are different.20-23 These photo-induced reactions involve ring-opening (spiropyrans), cis-trans isomerization (azobenzene), phenyl migration (phenoxyquinones), and ring-closure (bisthienylethene). In general, the photo-generated isomers return to the initials upon visible light irradiation. Among the photochromic compounds, diarylethene derivatives are one of the most appealing materials because of their remarkably high photo-reactivity, photofatigue resistance, short response time as well as absence of thermal isomeriazation and large change in their optical and electronic properties upon irradiation with UV and visible light. 24-26As shown in Scheme 1, diarylethenes can undergo reversible photocyclization between open-ring and closed-ring isomers under irradiation with UV and visible light, respectively. Photochromic studies of diarylethenes in organic solvents, 27 aqueous solutions, 28,29 polymer matrices 30,31 and metal-organic frameworks 33,34 have been conducted. However, there are very few studies about electrospun fibers containing diarylethene molecules. 35In this study, we fabricated diarylethene-embedded electrospun polymer fibers and demonstrated that micro-patterned images can be generated on the electrospun fiber mats through the selective transformation of the diarylethene molecules using photomasked UV irradiation. The patterns can be erased and rewritten without losing the integrity of the images. We also found that the patterned images last for over 30 days in the dark condition. ExperimentalMaterials and Instruments. The photochromic diarylethene 1,2-bis(2,3-dimethyl-5-phenyl-3-thienyl)-3,3,4,4,5,5-hexafluoro-1-cyclopentene was purchased from TCI. Polystyrene (PS) (Mw = 280,000 gmol) and polyacrylic acid (PAA) (Mw = 450,000 gmol −1 ) were purchased from Aldrich. SEM images of the diarylethene-embedded fibers were obtained by using a JEOL (JSM-6330F) FE-SEM instrument. The UV-irradiated diarylethene-containing fibers were coated with Pt for 15 s. SEM images were obtained at an accelerating voltage of 15 kV. Optical images were observed with an Olympus microscope (IX71).Preparation of Diarylethene-Embedded Electrospun PS Fibers. A typical procedure for fabrication of the diarylethene-encapsulated electrospun polymer fiber is as follows. A chloroform and N,N-diformamide solution (95:5 by volume, 3 mL, containing diarylethene (15 mg) and PS (1092.9 mg, Mw = 280,000 gmol −1 ), was pumped through a 25 G metal syringe needle at a constant rate of 0.8 mL/h by using a syringe pump (KD Scientific model 200 series). Application of a high voltage (11 kV) to the metal syringe needle allowed generation of microfibers, which were collected on the surface of a grounded aluminium plate (the working distance between the ti...

Fatigue‐Resistant Crosslinked Azopolymers with Inhibited H‐Aggregation for Efficient Photopatterning

“…The high fatigue resistance of the film is considered to be attributed to the photoswitching mechanism and structure of the polymers. The previously used photo‐rewritable media, mainly contained spiropyrans, oxazines, [26] and diarylethenes [50] . The color change was considered to be associated with bond cleavage (ring‐opening) and bond formation (ring‐closing) with significant differences in their electronic states between open and closed forms.…”

“…The previously used photo-rewritable media, mainly contained spiropyrans, oxazines, [26] and diarylethenes. [50] The color change was considered to be associated with bond cleavage (ring-opening) and bond formation (ring-closing) with significant differences in their electronic states between open and closed forms. For some of these molecules, the fatigue resistance was not high due to the inevitable side-reaction taking place in the photoisomerization process.…”

Photochromic Nanofibers

“…Lee and Kim [42] have prepared the diarylethene-loaded polystyrene (PS) and polyacrylic acid (PAA) fibers by electrospinning method, and then they have studied on the image recording properties of the electrospun photochromic fibers. The diameter of the diarylethene-doped PAA fibers has been smaller than the diameter of the diarylethene-doped PS fibers, thereby increasing the resolution of patterned color images which were created on the electrospun mat upon photomasked UV irradiation.…”

Using Azo-Compounds to Endow Biobased Thermosetting Coatings with Potential Application for Reversible Information Storage

“…Many delivery media are discarded after one-time reading, resulting in a severe waste of resources and environmental pollution. New technologies of erasable ink − and rewritable media , have been developed to reduce paper and electronic wastes. Azobenzene and its derivatives have reversible cis–trans photoisomerization abilities.…”