We report a first observation of nanoscale surface structures of segregated pinned micelles of grafted Y-shaped molecules and their reversible structural reorganization. We designed a novel type of Y-shaped molecules combining two highly incompatible polymer chains (arms) attached to a single focal point capable of chemical grafting to a functionalized silicon surface. We demonstrated that spatial constraints induced by a chemical junction of two dissimilar (hydrophobic and hydrophilic) polymer arms in such Y-shaped molecules lead to the formation of a novel type of segregated pinned micellar structures in chemically grafted brush layers. We propose a model of segregated pinned micelles and corresponding reverse micelles featuring different segregation states of polystyrene and poly(acrylic acid) arms. These arms are capable of local reversible rearrangements leading to reversible surface structural reorganization in different solvents.