A lactam-functionalized polymer is disclosed. The dihydroxy lactam based polymer includes polyesters, polycarbonates, polyethers, poly (ester ethers), poly (ester amides), poly imides, polyamides, poly acrylates and poly (ester imides), and polyurethanes. The applications of the dihydroxy lactam based polymers are also disclosed.

A spraying agent that includes a resin emulsion, and is used for at least one of agglomeration of soil, immobilization of seeds or plants, and immobilization of a chemical agent, in which the resin emulsion includes a biodegradable resin containing an ester skeleton and having a minimum film-forming temperature of 30 C. or lower. Further, a resin sheet that is formed of a resin composition containing the above-described resin emulsion.