title: Mechanism for rapid self-assembly of block copolymer nanoparticles.
abstract: Amphiphilic block copolymers in solution spontaneously self-assemble when the solvent quality for one block is selectively decreased. We demonstrate that, for supersaturation ratio changes [d(S)/dt] over 10(5) per second from equilibrium, nanoparticles are obtained with a formation mechanism and size dependent on the jumping rate and magnitude. The threshold rate for homogeneous precipitation is determined by the induction time of a particle, equivalent to the diffusion limited fusion of copolymer chains to form a corona of overlapping soluble brushes. Via determination of the induction time with a novel confined impinging jets mixer and use of a scaling relation, the interfacial free energy of a block copolymer nanoparticle was measured for the first time.
authors.affiliation: Princeton University, Department of Chemical Engineering, Princeton, New Jersey 08544, USA.
authors.forename: Brian K
authors.initials: BK
authors.lastname: Johnson
authors.forename: Robert K
authors.initials: RK
authors.lastname: Prud'homme