Static and dynamic control of phase separation structures in nanoparticles of polymer blends

Abstract

This paper reports static and dynamic control of the phase separation structures of polymer blended nanoparticles. The phase separated nanoparticles were prepared from various combinations of polymers by evaporating good solvents from the polymer blended solutions after adding poor solvents into the solutions. Transmission electron microscope observation of the nanoparticles shows that two types of phase separation structures were formed in them. One is Janus type structure and another is core-shell type structure. When the difference of the Flory-Huggins solubility parameter (d) between two blended polymers is large, one polymer having a higher d value encapsulated another polymer. As a result, a core-shell type structure is formed. On the other hand, when the difference of d value is small, both moieties of polymer are exposed to the poor solvent, and then, a Janus structure is formed. Moreover, when the thermoresponsive polymer was blended with a hydrophobic polymer, a Janus type or core-shell structure was formed by changing the preparation temperature. The core-shell type structure was transformed to a Janus type structure by heating the nanoparticles. This control and transformation of structures of nanoparticles can be applied to nano-sensing devices, switching devices and drug delivery systems.

Hierarchical assembly of CdS nanoparticles in polymer particles with phase separation structures

“…A clear Janus structure is observed. As shown in a previous report, 26 PS and PI have similar solubility parameters; thus, these two polymers simultaneously precipitate as blend particles into the poor solvent. After precipitation, a Janus-type phase separation structure spontaneously forms to minimize the interface between the two phases.…”

“…[20][21][22][23][24][25] Recently, it was reported that the inner structure of polymer blend particles could be controlled by the hydrophobicity of blended polymers. 26 We have also found that block copolymer-stabilized Au nanoparticles can be introduced into polymer blend particles by the self-organized precipitation method. 27,28 In this report, we describe the control of a special arrangement of CdS nanoparticles in submicron-sized polymer particles by using the self-assembly of polymer blends and block copolymers.…”

Creation of Functional and Structured Polymer Particles by Self-Organized Precipitation (SORP)

“…The homopolymers were dissolved in THF, and water was used as a poor solvent. A coreshell phase separation structure was observed in the blend of particles comprising PI and poly(isobutylene) (PIB), 34 which is a more hydrophobic polymer than PI. In this case, PIB formed the core parts, and PI the shell parts.…”

Facile Phase‐Separation Approach to Encapsulate Functionalized Polymers in Core–Shell Nanoparticles

“…Motoyoshi et al [ 36 ] prepared various composite nanoparticles by mixing two polymers in tetrahydrofuran (THF), dropping the solution in water, and then evaporating the THF. The difference between the Flory-Huggins solubility parameter ( δ ) for the two polymers infl uenced the morphologies of nanoparticles.…”