Polymer dispersant for cellulose, aqueous dispersion treatment agent containing same, readily dispersible cellulose composition, cellulose dispersion resin composition, and dispersant-containing resin composition for cellulose dispersion

The purposes of the present invention are to provide a high-performance polymer dispersant that can be applied to cellulose that is a hydrophilic substance and to achieve a practical technique for obtaining a cellulose dispersion resin composition that, when the polymer dispersant for cellulose is applied to cellulose and the result is dispersed within a thermoplastic resin, makes it easier to achieve a stable dispersion of cellulose using a method that does not use a large amount of an organic solvent and that is environmentally friendly. This objective is achieved by configuring a polymer dispersant for cellulose that is a polymer compound that has a block copolymer structure that includes a segment (A) that has resin affinity and a segment (B) that has cellulose-adsorbing properties, said polymer dispersant for cellulose being synthesized by reversible chain transfer catalyzed polymerization (RTCP) in which no heavy metals, nitroxide compounds, or sulfur-based compounds are used, an organic iodine compound is used as a starting compound, and a phosphorus compound, a nitrogen compound, an oxygen compound, or a carbon compound is used as a catalyst.