Abstract
In this paper, we investigated the effect of annealing on the phase separation structures formed in block copolymer nanoparticles. The nanoparticles with the lamellar structures were prepared by evaporation of tetrahydrofuran (THF) from the THF/water solution of poly(styrene-b-isoprene). Scanning transmission electron microscope (STEM) observation revealed that the consecutive lamellar structure was formed one-directionally in the nanoparticles. When the suspension of lamellar-structured nanoparticles was annealed at 50°C for 10 h, the lamellar phase changed to a disordered structure. This transition was irreversible. This result shows the lamellar structure formed in nanoparticles is less stable than that in the planar film.
