Electrostatic manipulation of triblock terpolymer nanofilm compartmentalization has been achieved via visible light-initiated reversible addition-fragmentation chain transfer aqueous dispersion polymerization of diacetone acrylamide monomer using cationic-neutral diblock copolymer macro-chain transfer agent (macro-CTA) at 25 degrees C. This photoinitiated polymerization-induced self-assembly (photo-PISA) evolves into two modes depending on solution pH. At pH 2.5, this macro-CTA dissolves in water with a fully cationic block; electrostatic repulsion leads to conventional aqueous photo-PISA and the formation of monolayer colloidal nanofilms. At pH 7.3, the cationic block transforms to a hydrophobic ionomer block with 10% cationic repeat units, and the copolymer chains self-assemble into weakly cationic micelles, which leads to seeded photo-PISA via self-assembly into discrete nanoclusters within the hydrophobic lamellar framework to form multicompartmentalized monolayer nanofilms. The nanoscale phase-separated 2D-confined nanoclusters and the lamellar structure can be tuned by the ABC/BAC block sequence, the degree of polymerization of the growing block, and the copolymer concentration. This electrostatic manipulation sheds new light on the rational design and preparation of multicompartmentalized block copolymer 2D nanoobjects.