The paper describes the synthesis, properties and applications of magnetic polymer beads. State-of-the-art, future challenges, and promising trends in this field are analyzed. New applications in oil recovery are described

This review surveys the main methods of preparing chitosan and its hydrophobic derivatives and their influence on the microstructure of polymers. The experimental data on the aggregation of these polymers in dilute aqueous solutions are summarized. Basic factors affecting aggregation are analyzed, and its general regularities are revealed. It is shown that, in the case of both chitosan and its hydrophobic derivatives, the formation of aggregates is governed by the competition of attraction of associating groups promoting aggregation and their repulsion arising from the presence of charged units and counterions hindering aggregation. Various aggregate models that were proposed for chitosan derivatives with different main-chain lengths and different contents of associating groups are discussed.