Polymer dispersity (D) is an important parameter in determining polymer properties. We report a new strategy for D modulation by statistical copolymerizing steric-hindered itaconates with methacrylate and acrylate monomers via organocatalyzed controlled radical polymerization. Due to the disparate monomer reactivity, D values can be tunable in a broad range (1.1-1.6) in a batch system. This strategy has demonstrated the sequential and topological control and D modulations, serving as a model tool for D modulation in any segment of A-B diblock, B-A-B and A-B-A triblock, and 3-arm star A-B diblock copolymers. The unique aspects of this method are that the segment after D modulation can initiate polymerization of various types of monomers (e.g., methacrylate, acrylate) by the labile tertiary carbon-iodide chain-end without any external assistance or special initiator and monomer selection, the metal-free nature and the renewable substitution of petroleum-based methacrylate and acrylate monomers with bio-based itaconates without sacrificing inherent properties. This work broadens the application scope of D modulation to many other emerging technologies, such as antifreezing thermoplastic dielectric elastomers used as film capacitors in the field of energy storage.