Accession Number : ADA193334

Title :   Energy Migration, Motion and Order in Synthetic Polymers.

Descriptive Note : Periodic rept. no. 2, Jun-Dec 87,

Corporate Author : ROYAL INSTITUTION OF GREAT BRITAIN LONDON (ENGLAND)

Personal Author(s) : Phillips, David

PDF Url : ADA193334

Report Date : Dec 1987

Pagination or Media Count : 13

Abstract : The initial phase of this work has been concerned exclusively with the luminescence of poly(diacetylenes), so-called one-dimensional polymers. The chemical structures of some commonly met conjugated polymers are given in Table 1. Of these, PDA's are virtually unique in that they are obtainable as single crystals, and have been selected for study here. The materials studied are the BCMU family, of structure indicated in Table 2. In discussing the chromism of Poly Diacetylenes PDA's it is important first to note there are fewer fluorescing forms than absorbing ones. This is because the R form consists of lone sections of continuously conjugated backbone - be it LCS, wormlike or rigid rods (Figure 4). These forms, as in 'infinitely' conjugated crystals, have a very efficient non-radiative pathway which reduces the quantum yield on transition from Y to R forms. In 4BCMU the red-shifted forms do fluoresce although the quantum yield decreases with decreasing Xc. The presence of an isosbestic point is an important feature of PDA chromism which indicates a phase transition of the polymer without formation of stable, optically detectable, intermediates.

Descriptors :   *ACETYLENES, *POLYMERS, CRYSTALS, EFFICIENCY, ENERGY, LUMINESCENCE, MIGRATION, ONE DIMENSIONAL, PHASE TRANSFORMATIONS, QUANTUM THEORY, SINGLE CRYSTALS, TRANSITIONS, YIELD

Subject Categories : Organic Chemistry
      Polymer Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE