NMRP versus Click Chemistry for the Synthesis of Semiconductor Polymers Carrying Pendant Perylene Bisimides

The synthesis of well-defined polymers with pendant perylene bisimide (PBI) groups by a combination of nitroxide-mediated radical polymerization (NMRP) of trimethylsilyl propargyl acrylate followed by copper-catalyzed azide-alkyne cycloaddition (CuAAC, click chemistry) is described. The kinetics of NMRP of trimethylsilyl propargyl acrylate polymerization was monitored by H-1 NMR and size exclusion chromatography (SEC). Almost quantitative conversion in the click reaction with an azide functionalized PBI derivative was proven by Fritz and H-1 NMR analysis. Thus, semiconductor polymers carrying PBI pendant groups with M-n up to 15800 g.mol(-1) and polydispersity indices as good as 1.16 were obtained by this route. These polymers were compared with poly(perylene bisimide acrylate)s, PPerAcr-(CH2)(11), and PPerAcr(CH2)(6), which were synthesized by direct NMRP of PBI acrylates. These samples do not carry any triazol unit and they differ in their spacer length connecting the PBI unit to the main chain. All polymers were comparatively studied by SEC, thermogravimetry, differential scanning calorimetry, polarization microscopy, UV/vis spectroscopy, and photoluminescence measurements. The crystalline structure of the polymers was analyzed by X-ray diffraction. Inductively coupled plasma mass spectrometry analysis confirmed that copper content in the click polymer could be reduced down to 126 ppm (w/w).