Biodegradable graft copolymers derived from a carbohydrate, including nitrogen- containing carbohydrates and modified carbohydrates, and at least one α,β-unsaturated carboxylic acid derivative having superabsorbent properties are disclosed in addition to the substantially adiabatic polymerization process by which the graft copolymers are made. The methods disclosed can be carried out in a variety of currently available stirred and/or continuous commercial reactors. Polymerizations carried out with starch have surprisingly produced substantially quantitative yields of graft copolymer free of residual monomer produced as a moist copolymer. Product work-up typically involves an optional neutralization and drying.