Find in Library

A series of poly(alkyl methacrylate)s and poly(oligo(ethylene glycol) methyl ether methacrylate)s labeled with 1-pyrenebutanol were referred to as the PyC₄-PC_nMA samples with <i>n</i> = 1, 4, 6, 8, 12, and 18 and the PyC₄-PEG_nMA samples with <i>n</i> = 0–5, 9, 16, and 19, respectively. Pyrene excimer formation (PEF) upon the encounter between an excited and a ground-state pyrenyl labels was employed to determine their persistence length (<i>l</i>_p) in <i>o</i>-xylene. The fluorescence decays of the PyC₄-PC_nMA and PyC₄-PEG_nMA samples were acquired and analyzed with the fluorescence blob model to yield the number (<i>N</i>_blob) of structural units in the volume probed by an excited pyrenyl label. <i>N</i>_blob was found to decrease with an increasing number (<i>N</i>_S) of non-hydrogen atoms in the side chain, reaching a plateau for the PyC₄-PEG_nMA samples with a longer side chain (<i>n</i> = 16 and 19). The <i>N</i>_blob values were used to determine <i>l</i>_p. The <i>l</i>_p values for the PyC₄-PC_nMA and PyC₄-PEG_nMA samples increased linearly with increasing <i>N</i>_S² as predicted theoretically, which agreed with the <i>l</i>_p values obtained by viscometry for a series of PC_nMA samples. The good agreement between the <i>l</i>_p values retrieved by PEF and viscometry served to validate the PEF-based methodology for determining <i>l</i>_p for linear polymers.