Polyacrylamide Containing Weak Temperature Labile Azo Links in the Polymer Backbone

Degradable polyacrylamide (PAAm) was prepared by incorporating temperature-sensitive azo groups into the polymer backbone. Ceric ions (Ce(IV)) and 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)-propionamidel were used as a redox couple to initiate the polymerization of acrylamide. The presence of azo groups in the backbone of the synthesized polyacrylamide was confirmed by (HNMR)-H-1 spectra, DSC, and by the fact that the polymerization of acrylonitrile could be initiated using the synthesized polyacrylamide with built-in azo groups as a macroinitiator. Drag reduction properties of the synthesized polyacrylamide with incorporated azo groups were quantified. It was found that polyacrylamide with azo links in the polymer backbone is as good a drag reducing agent as pure polyacrylamide. However, PAAm with azo links in the backbone degrades into smaller molecular weight fragments and, therefore, loses its drag reduction properties once subjected to elevated temperature, which for some applications is seen as an advantage. The degradation behavior of the PAAm with temperature-sensitive azo groups was characterized using GPC.