Formation of mesoglobules from phase separation in dilute polymer solutions: a study in experiment, theory, and applications

The appearance of spherical particles resulting from heating beyond the phase separation temperature in dilute solutions of poly(N-isopropylacrylamide) has been observed by dynamic light scattering (DLS). They have a relatively narrow size distribution. The size of particles increases with increasing concentration of polymer, and decreasing heating speed. Electron microscopy confirms the existence of spherical particles with size and polydispersity in agreement with DLS. We develop a theory based on the Gaussian self-consistent method for study of the equilibrium and kinetics of conformational transitions in homopolymer solutions. The theory leads to a natural interpretation of the mesoglobules as a very long-lived metastable state. Finally, we mention the potential for these mesoglobules to find applications.