Segregation Kinetics of Biphasic Polymer Brushes Grafted from Spherical Substrates: Insights from Simulation

Polymer brushes grafted onto curved substrates represent a minimal model system for understanding how confinement and geometry regulate phase separation. While equilibrium morphologies of such systems have been widely explored, their nonequilibrium coarsening dynamics remain largely unresolved. We study the self-assembly kinetics of symmetric, chemically incompatible, A- and B-type, biphasic polymer brushes randomly grafted from spherical substrates using coarse-grained dissipative particle dynamics simulations. By systematically varying chain length, grafting density, and solvent quality across solvophilic to solvophobic conditions, we demonstrate controlled tuning of cluster connectivity, interfacial sharpness, and surface microsegregation patterns. We quantify the morphological evolution by the time-dependent growth of a characteristic domain length. We show that spherical confinement strongly influences domain coarsening, slowing the power-law growth at early times. At later times, a gradual crossover to a pronounced reduction in the growth rate is demonstrated. Our results identify solvent selectivity, chain length, and grafting density as decisive parameters governing kinetic arrest and domain stabilization in binary polymer brushes. The results provide mechanistic insight into microphase separation on modified surfaces and offer design principles for patchy colloids, biointerfacial architectures, and stimuli-responsive polymer coatings.