Hydrodynamic modulation of sequence-dependent compaction in active–passive copolymers

Sequence patterning has recently emerged as a route to control the conformations of active-passive copolymers, but most studies have used free-draining models in which the solvent acts only as a local dissipative bath. Here, we ask whether hydrodynamic interactions can alter the nonequilibrium conformation selected by an active-passive sequence. We simulate a self-avoiding polymer with a fixed fraction of active Ornstein-Uhlenbeck monomers arranged in different sequences and compare free-draining dynamics with simulations including Rotne-Prager-Yamakawa hydrodynamic interactions. Increasing sequence blockiness drives a non-monotonic conformational response from expansion to compaction and then re-expansion. Hydrodynamic interactions preserve this qualitative sequence dependence but shift the compact regime, alter the degree of compaction and mechanical size balance, and render center-of-mass transport sequence-dependent. At intermediate blockiness, the compact state is accompanied by a suppressed active contribution to radial swelling and develops an internally segregated structure with a passive-rich core and active peripheral protrusions. At larger blockiness, the polymer re-expands despite this suppression, with the increase in size arising instead from the growing spatial separation between the active and passive blocks. This block separation is reduced by hydrodynamic interactions, thereby modifying the high-blockiness conformations. Formation of the compact state proceeds through rapid global compaction followed by slower radial reorganization, leaving the active segments dynamically constrained in the compact state. These results show that hydrodynamic interactions do more than renormalize relaxation. They reshape the sequence-selected conformational landscape and couple internal organization to long-time transport in active-passive copolymers.