Organoboron-Based Photochromic Copolymers for Erasable Writing and Patterning

We report herein the first examples of organoboron-based photochromic polymers. The synthesis of a series of blue fluorescent random copolymers bearing photochromic boron repeating units, poly[(6-B(ppy)Mes₂)oxyhexyl methacrylate)_m-r-(tert-butyl methacrylate)_n], ppy = 2-phenylpyridyl and Mes = mesityl, via atom transfer free radical polymerization (ATRP) has been accomplished. These new polymers display thermally reversible photochromism, switching color from colorless to deep blue, and fluorescence from bright sky blue to deep blue. By controlling the monomer ratio, the photoisomerization quantum efficiencies of the polymers can be tuned effectively. In addition, the number of boron units in the polymer has been found to have a significant impact on fluorescence quenching efficiency. The new organoboron-based polymers can be used effectively as a switchable/erasable ink on glass or paper substrate or for creating switchable/erasable patterns as neat polymer films.