The application of a photochromic probe to monitor the self-assembly of thermosensitive block copolymers

Abstract

Analysis of the thermal decolouration kinetics of a spirooxazine dye (SOX) incorporated into various thermally responsive, amphiphilc block copolymers, poly(N-isopropyl acrylamide)-block-poly(Nacryloyl morpholine), was used to probe their self-assembly behaviour in water. The Arrhenius plots of the thermal decolouration kinetics for each of the block copolymers displayed a deviation from linearity and this occurred within a temperature range that correlated with their self-assembly into micelles, as measured by dynamic light scattering (DLS). The block copolymers containing SOX units within the PNIPAM section displayed the most notable deviations. The results were interpreted in terms of a change in the local viscosity and polarity sensed by the photochromic probe and its effect on the transition state of the open form on progression to the closed form. The incorporation of the free dye, SOX-PROP, within micelles assembled from amphiphilc poly(n-butyl acrylate)-block-poly(Nacryloyl morpholine), was also apparent from the measured decolouration kinetics.

Surface‐Adhered Composite Poly(Vinyl Alcohol) Physical Hydrogels: Polymersome‐Aided Delivery of Therapeutic Small Molecules

“…The block copolymer was formed by extension of PChA with NAM. [ 30 ] The two arms were comprised of approximately 21 repeat units of NAM, giving an overall molecular weight of the ABA triblock of 28.4 kDa and a PDI of 1.15.…”

Light and temperature responsive block copolymer assemblies with tunable fluorescence emissions

“…The fluorescence around 523 nm can be recovered to 81.5% of its original value within 6 min after keeping the sample in the dark at 55 C. We consider a higher temperature that does not induce thermal ring opening process for the naphthopyrans (Fig. S5 in the Supporting Information) can promote most of the opened merocyanine forms to revert to their opposite closed forms rapidly [41,42]. It should be noted that the value is higher and the time is shorter than those at 25 C (Fig.…”

Ultrasound-aided dyeing of cotton fabric with spirooxazines and photochromic properties

“…Therefore, novel spirooxazine derivatives need to be developed to improve the photochromic effects of Spirooxazine A. In contrast, Nmethyl-3,3-dimethyl-9'-dichloro-s-triazine group spiro [2H-indole-2'-[3H] naphtho [2,1-b] [1,4]oxazine] (denoted here as Spirooxazine B), a spirooxazine derivative that contains the -Cl group, can be chemically bonded onto textiles, such as cotton, wool, and silk, because the -Cl group can react with -OH in the textile fibers. However, there have been no reports on the synthesis of Spirooxazine B and dyeing of textiles with Spirooxazine B.…”

“…A thin layer of hybrid silica-photochromic dye was coated onto the surface of wool to produce photochromic wool fabrics by using the sol-gel process, and the durability of the photochromic coated layer was improved by introducing epoxy groups into the silica matrix [11]. Currently, N-methyl-3,3-dimethyl-9'-hydroxy- [1,4] oxazine] (denoted here as Spirooxazine A) a spirooxazine, is frequently applied to natural and synthetic fibers, such as wool, cotton, polyester, and nylon, to obtain photochromic properties [22][23][24][25][26][27]. However, no chemical bonds are formed between Spirooxazine A and textile fibers, consequently, Spirooxazine A would be removed after washing.…”

“…The dyes revert back to their original color, either thermally when the light source is removed, or by irradiation with different wavelengths of light. Currently, photochromic dyes are most widely applied in protective ophthalmic lenses, and could be potentially used in security printing, optical memory and switching, solar energy storage, nonlinear optics and biological systems, cosmetics, and electrophoretic displays [3][4][5][6]. There has also been considerable recent interest in the use of photochromic dyes for textiles in view of developing functional or smart products, such as those with the ability to screen UV radiation, used as UV sensors and camouflage, in security printing, for brand protection and authentication, as well as in design applications [7,8].…”