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Fluorescence and aggregation behavior of a polyimide in solutions
Author(s) -
Luo Haobin,
Dong Lisong,
Tang Hao,
Teng Fengen,
Feng Zhiliu
Publication year - 1999
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/(sici)1521-3935(19990301)200:3<629::aid-macp629>3.0.co;2-p
Subject(s) - intermolecular force , intramolecular force , chemistry , polyimide , dimethylacetamide , excited state , fluorescence , photochemistry , acceptor , molecule , chloroform , absorption (acoustics) , solvent , analytical chemistry (journal) , materials science , organic chemistry , physics , layer (electronics) , quantum mechanics , nuclear physics , composite material , condensed matter physics
The UV‐visible absorption and fluorescence spectra of a soluble polyimide, YS‐30, in several organic solvents were measured over a wide range of concentration. The experimental results show that there exist both intramolecular and intermolecular electron donor acceptor interactions for YS‐30 molecules. The fluorescence behavior of YS‐30 in N , N ‐dimethylacetamide and in chloroform solutions is similar in general, except that its ground‐state intermolecular charge transfer emission is more obvious in N , N ‐dimethylacetamide solution. This difference is attributed to the greater extent of disruption of the chain packing by solvent or/and the more efficient radiationless energy dissipation process from the excited state complexes to chloroform. The intensity ratio of intermolecular charge transfer emission to intramolecular charge transfer emission is used to characterize the state of aggregation of YS‐30 molecules in solutions. The plot of this ratio versus concentration indicates the existence of two critical concentrations. It is also found from the same plot that the decrease of coil size is very pronounced during the initial stage of shrinkage.