Photochromism of spirofluorenylindolizines

Abstract

The decoloration kinetics of three spirofluorenylindolizines have been followed in solution and in polymer matrix. They are the 5′‐methyl‐spiro[9H‐fluorene‐9.1′(1′H)‐indolizine]‐2′‐3′‐bis‐methoxycarbonyl (I), its methacryloyl oxymethyl (II) derivative, and the copolymers of (II) with ethyl acrylate. In solution the reactions follow first‐order kinetics and show pronounced negative solvatochromism. In solid polymer film, the incorporation of the photochrome as side group of polyethylacrylate affects strongly the decoloration below Tg of the film. Above Tg the decoloration was interpreted on the basis of the WLF equation.

Photochromic Polymers

“…16 2-Methacryloyloxymethylpyridine was prepared by the reaction of 2-hydroxymethylpyridine with methacryloyl chloride in benzene in the presence of triethylamine and condensed with the corresponding spirocyclopropenefluorene compound to give a photochromic monomer (11, Figure 3). Fifty milligrams of 11, 950 mg of ethyl methacrylate, and 5 mg of AIBN were dissolved in 5 ml of butanone and polymerized under a nitrogen atmosphere at 65°C.…”

“…16 The monomer (11) was prepared by the condensation of 2-methacryloyloxymethylpyridine and the corresponding spirocyclopropenefluorene compound according to Dürr's procedure. 15 The momoner was copolymerized with ethyl methacrylate to give a polymer containing 1.1 mol% of the photochromic unit with…”

Anionic living polymerization of useful monomers that can provide intermolecular chemical links

“…Such deviation from the first-order plots has been qualitatively discussed on the basis of a distribution of a free volume [49][50][51]. The departures from the first-order kinetics in polymer matrices have been analyzed quantitatively by Saito et al [52] and Tomioka et al…”