Multicompartment Micelles from Polyester-Containing ABC Miktoarm Star Terpolymers
Naohiko Saito
Chun Liu
Timothy P. Lodge
Marc A. Hillmyer
10.1021/ma801001s.s001
https://acs.figshare.com/articles/journal_contribution/Multicompartment_Micelles_from_Polyester_Containing_ABC_Miktoarm_Star_Terpolymers/2897539
Well-defined μ-[poly(ethylethylene)][poly(ethylene oxide)][poly(γ-methyl-ε-caprolactone)] (μ-EOC) miktoarm star terpolymers were prepared by a combination of two successive living anionic polymerizations and one controlled ring-opening polymerization (ROP). A mid-hydroxyl-functionalized poly(ethylethylene)-<i>block</i>-poly(ethylene oxide) (PEE−PEO) diblock copolymer served as a macroinitiator for the aluminum-mediated ROP of γ-methyl-ε-caprolactone (MCL), leading to a family of μ-EOC triblock copolymers having monomodal molecular weight distributions and controlled PMCL weight fractions. Micelle structures formed in water from μ-EOC containing various lengths of PMCL were examined by cryogenic transmission electron microscopy (cryo-TEM) and dynamic light scattering. Increasing the fraction of hydrophobic PMCL resulted in a transition from spherical to wormlike to approximately spherical micelles. Although the multicompartment cores of the μ-EOC micelles could not be directly resolved by cryo-TEM, small-angle X-ray scattering analysis of a representative PEE−PMCL diblock copolymer showed clear microphase separation, strongly suggesting the existence of multicompartment cores in the μ-EOC micelles. We speculate that the transition of μ-EOC micelles from worms to spheres can be attributed to the connection of the three immiscible blocks at one junction and documented micellar transitions in analogous PMCL−PEO diblock micelles.
2008-11-25 00:00:00
EOC
cryogenic transmission electron microscopy
miktoarm star terpolymers
ROP
micelle
transition
multicompartment cores
PEE
ABC
PMCL weight fractions
diblock