BODIPY-Conjugated Thermo-Sensitive Fluorescent Polymers Based On 2-(2-methoxyethoxy)ethyl methacrylate

A methacrylic monomer containing the dye 4,4-difluoro-4-bora-3a,4a-diaza-<i>s</i>-indacene (BODIPYMA) was synthesized to provide fluorescence properties to three different thermo-sensitive families of polymers based on 2-(2-methoxyethoxy)ethyl methacrylate (MEO<sub>2</sub>MA). Initially, linear random terpolymers of MEO<sub>2</sub>MA, oligo(ethylene glycol) methyl ether methacrylate (OEG<sub>8−9</sub>MA) with <i>M</i><sub>n</sub> = 475 g mol<sup>−1</sup>, and a very low proportion of BODIPYMA were synthesized by atom transfer radical polymerization (ATRP). These terpolymers showed lower critical solution temperature (LCST), which values were easily tuned by changing the monomeric composition, and fluorescence, which intensity increases significantly after this thermal transition. Second, a family of diblock copolymers was formed by the ATRP of MEO<sub>2</sub>MA and a very short block of BODIPYMA. They also behave as a fluorescent thermometer in water but, in this case, the fluorescence quantum yield decreased due to the intermolecular π−π stacking of BODIPY dyes. In addition, a MEO<sub>2</sub>MA−BODIPYMA based hydrogel was prepared to show that the optical and fluorescence properties also exhibit a sudden and reversible change at the volume transition temperature (VTT) of the hydrogel.