Tuning the color switching of naphthopyrans via the control of polymeric architectures

Abstract

A range of polymerisable photochromic naphthopyrans were prepared via the synthesis of an acrylate moiety on either the naphthalene ring (R) and/or the di-aryl (Ar) rings on the 3-position of the naphthopyran. The monomers obtained (NA) were copolymerised with methyl methacrylate (MMA) and methyl acrylate (MA) by the RAFT (reversible addition fragmentation chain transfer) process in order to control the structure of the polymeric chains and accurately control the number of photochromic molecules per chain. Films were prepared with the synthesized photochromic polymers and their photochromic properties were assessed. We found that the fading rate of the photochromic dye was slower in a matrix of PMMA (higher T g ) than in a matrix of PMA (lower T g ). By producing block copolymers of PMMA-b-poly(MA-co-NA), the fading rate was increased, and the production of PS-b-poly(MA-co-NA) further enhanced the speed of switching, as phase separation occurred between the poly(MA-co-NA) block and the PS block. This study presents an example of tuning the photochromic properties of a dye via variation of the architecture of its polymeric support.

The use of poly(alkylene oxide)s to achieve fast and controlled photochromic switching in rigid matrices

“…Despite this, the application of biexponential kinetics in this work provided correlation coefficients greater than 0.99 in all analyses, which is in part a result of the greater solution‐like character of decoloration attained upon conjugation of the photochrome with soft oligomers (as the results that follow will show). In addition, this is the most common model used for photochromic analysis in solid media and allows comparison to other literature reported values 24–26. Spectrokinetic data for all compounds tested is presented in Table 2, which also includes values of t 1/2 and t 3/4 , defined as the time taken for the initial absorbance ( A 0 ) to be reduced by half and three quarters, respectively, during decoloration in the dark.…”

Highly efficient light-induced reversible micellization of amphiphilic polymer based on photochromism of naphthopyran in aqueous solution

“…They display the ability of reversible color changes and undergo highly efficient photoreversible isomerization which results in the merocyanine (MC) moiety with significant difference in the polarity and the spatial structure of molecule when exposed to UV irradiation [10]. In addition, naphthopyrans have the advantages in commercial application in optical memories, optical and electrical switching, and light-actuated nanovalves due to their special optical properties such as the breadth of color generated, absence of background color, fine control over fading kinetics and good resistance to photochemical fatigue [11]. For these properties, the naphthopyrans were used as the hydrophobic and the light-responsive block for the preparation of amphiphilic polymeric micelles in this work.…”

Light and temperature responsive block copolymer assemblies with tunable fluorescence emissions

“…Naphthopyrans, a type of important photochromic compounds [17], present two major colored merocyanine forms (transoid-cis, TC, and transoid-trans, TT) upon continuous UV light irradiation, whereas they convert to the closed form in the dark or under visible light. Moreover, naphthopyrans possess some advantages for their applications in optical switches, optical memories and ophthalmic lenses because of their special properties, such as fine control over fading kinetics and good thermal reversibility [18].…”