Synthesis and application of pH-responsive branched copolymer nanoparticles (PRBNs): a comparison with pH-responsive shell cross-linked micelles

pH-responsive polymers are both a fascinating and fundamentally important class of polymer. The ability to change their aqueous solution properties and behavior in response to simple external stimuli—that is, the addition of acid or base—places them uniquely as: (i) ‘building blocks’ for the fabrication of higher-order materials via self-assembly, (ii) controllable encapsulation and release devices and, (iii) useful synthetic mimics of highly complex natural biological systems. The fabrication of pH-responsive branched copolymer nanoparticles (PRBNs) which are capable of reversibly forming distinct ‘core–shell’ morphologies is an emerging class of material. In this highlight, we discuss key advances in the synthesis, characterization and application of branched pH-responsive copolymer nanoparticles and place these developments in the context of seemingly similar structures—most notably shell cross-linked micelles. We also speculate as to the scope, and limitations, of these branched materials in various commercial and fundamental applications