Polyacrylamide (PAM) is an essential additive for high temperature and salinity reservoir. In order to achieve well performance at harsh environment

PAM is required to be stable and display high viscosity at high temperature solution. Thermo-stability of PAM was greatly enhanced by copolymerization AM with temperature-stable and salt-tolerant monomers

and lots of efforts were made to summarize the achievements in this area. By contrast

less attention has been paid to the viscosity retention rate of PAM upon elevated temperature. Based on structure and solution property relationship

two aspects of recent developments about improving viscosity retention rate of PAM aqueous solution was reviewed in this article. One is increasing the rigidity of polymer chain by introducing side chain into linear PAM backbone. The other is altering the aggregation structure of PAM in water induced by supermolecular interaction in order to form physical cross-linking network. Some comments were also made on its development trend.