Collect. Czech. Chem. Commun. 1990, 55, 2226-2232

Microenvironment of polymer chains in solution: pKa of indicators bound to the polymer chain

František Mikeš, Jiří Labský, Drahomír Výprachtický and Jiří Chalabala

Institute of Macromolecular Chemistry, Czechoslovak Academy of Sciences, 162 06 Prague 6


Polymers bearing at the end of side chains acidobasic indicator moieties exhibiting a solvatochromic absorption band were prepared by a polymeranalogous reaction of copolymers N-(2-hydroxy propyl) methacrylamide-N-methacryloylated 4-nitrophenyl ester ω-aminoacids with 1-(2-aminoethyl)-4-(4-hydroxystyryl)pyridinium bromide. It was found that pKa of reporters bound at a medium long side chain (six methylene groups) is close to pKa of a low-molecular model compound, while pKa of a reporter bound close to the polymer backbone is approximately by one pKa unit higher. Changes in the pKa value of the reporters are discussed in connection with a change in the polarity of microenvironment of polymer chains.