Solution properties of self-assembling azo aromatic polymers

• Main Author: Norman, Lana Laurette
• Format: Others
• Language: en
• Published: McGill University 2003
• Subjects: Chemistry - Organic
• Online Access: http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=19563

Amphiphilic copolymers of hydrophobic Disperse Red 1 acrylate (DR1A) and hydrophilic acrylic acid (AA) were dissolved in THF and a H2O/THF co-solvent series. The thermal cis-trans isomerization behavior of the azo groups was measured by means of flash photolysis to investigate self-assembled structure in solution. The rate constants observed for the azo-containing polymers permit an estimation of how the thermal isomerization is influenced by both polymer and solution properties. In pure THF the relaxation can be analyzed by a monoexponential decay. In aqueous-organic solutions all poly(DRlA-co-AA) samples show a slow isomerization process due to inhibited mobility of the azo groups, preceded by a faster isomerization process for unaggregated azo groups. In such cases, the relaxation of the cz's-isomer was fit to a biexponential function which clearly demonstrates two distinct local chromophore environments. The spectroscopic results of this study suggest that weakly aggregated states of the amphiphilic polymers in an aqueous-organic solution can be readily studied through isomerization spectroscopy to estimate the fractions of aggregated groups involved and their local environment.