THERMAL-ISOMERIZATION OF AZOCHROMOPHORIC LABELS IN THE BACKBONE OF POLYAMIC ACIDS

Semiquantitative data describing the motion of the chains of polyamic acids in solution were obtained from the kinetics of the thermal cis t o trans isomerization of photoisomerized 4,4'-diaminoazobenzene labels incorporated into their main polymer chains. Labelled polyamic acids differing in chemical composition, based on pyromellitic dianhydride a nd 4,4'-diaminodiphenylmethane or 1,n-bis(4-aminophenoxy)alkanes were analyzed by using UV/VIS spectroscopy. The kinetic parameters calculat ed are discussed in relation to the structure of the explored polyamic acids and the conditions of the investigation.