  We investigate the dynamics of the collapse of a single copolymer chain, when
the solvent quality is suddenly quenched from good to poor. We employ Brownian
dynamics simulations of a bead-spring chain model and incorporate fluctuating
hydrodynamic interactions via the Rotne-Prager-Yamakawa tensor. Various
copolymer architectures are studied within the framework of a two-letter HP
model, where monomers of type H (hydrophobic) attract each other, while all
interactions involving P (polar or hydrophilic) monomers are purely repulsive.
The hydrodynamic interactions are found to assist the collapse. Furthermore,
the chain sequence has a strong influence on the kinetics and on the
compactness and energy of the final state. The dynamics is typically
characterised by initial rapid cluster formation, followed by coalescence and
final rearrangement to form the compact globule. The coalescence stage takes
most of the collapse time, and its duration is particularly sensitive to the
details of the architecture. Long blocks of type P are identified as the main
bottlenecks to find the globular state rapidly.
