APPLICATION OF THE SPECTROSCOPIC RULER TO STUDIES OF THE DIMENSIONS OF FLEXIBLE MACROMOLECULES .2. EXPERIMENTAL STUDIES OF POLY(METHYL METHACRYLATE) CHAINS

Energy-transfer efficiencies between end-labeled poly(methyl methacrylate) (PMMA) samples are determined in different media. With use of the formulas developed previously, they are then used to fit the root-mean-square end-to-end distances of PMMA chains. In nonviscous solvents, the values determined by the “spectroscopic ruler” technique are all considerably shorter than those from viscosity measurement. In a PMMA matrix, the end-to-end distances determined by this technique give a value close to that estimated from viscosity. Significant diffusion of the end groups during the donor excitation lifetime may be partially responsible for the observed discrepancies with static methods. © 1990, American Chemical Society. All rights reserved.