ABSTRACT
SCNP size (typically from 5 to 20 nm) is between maximum dendrimer size (5 nm) and minimum emulsion size (20 nm). SCNPs are obtained under high dilution conditions to avoid interparticle coupling events during their synthesis. Under such conditions, a signicant reduction in hydrodynamic size is observed upon intrachain cross-linking of the isolated polymer chain (Figure 591b). Consequently, SCNPs are also dened as individual intramolecular collapsed polymer chains.4 Contrary to classical hard nanoparticles such as gold, silver, or silica nanoparticles, SCNPs are also known as soft nanoparticles due to their polymeric character. Several typical characteristics of SCNPs include: (1) ultrasmall size, (2) huge surface-to-volume ratio, (3) resemblance to natural folded biomacromolecules (i.e., proteins),5 and (4) unusual and interesting macroscopic physical properties as a consequence of (1-3).6-12 SCNPs have demonstrated promise for use in enzyme mimetics, diagnostics, controlled release, chemical sensors, catalysis, nanoreactors, nanocomposites, and optics, being a relatively new research eld with signicant research and development activities.
