Abstract: A composition of matter including a yield stress fluid including self-assembled copolymers each including at least one first type of polymer covalently bonded to at least one second type of polymer, wherein the first type of polymer (“first block”) is microphase separated from the second type of polymer (“second block”), at least one of the first block or the second block has its glass transition temperature less than or equal to 20° C., and the yield stress fluid has a critical yield stress at room temperature or below room temperature, without addition of a solvent for the first block or the second block. Examples of the self-assembled copolymers include a diblock copolymer or bottlebrush copolymer including the first block covalently bonded to the second block.