Vesicle-to-spherical micelle-to-tubular nanostructure transition of monomethoxy-poly(ethylene glycol)-poly(trimethylene carbonate) diblock copolymer.
Recently, we reported a temperature-sensitive biodegradable diblock copolymer of monomethoxy-poly(ethylene glycol)-b-poly(trimethylene carbonate) (mPEG-PTMC; Macromolecules 2007, 40, 5519-5525). In this paper, we report the detailed morphological transition of the polymer in water as a function of polymer concentration and temperature, using cryo-transmission electron microscopy (cryo-TEM). At a low polymer concentration (0.05 wt %), the mPEG-PTMC diblock copolymers formed vesicles in water. On the other hand, vesicle-to-micelle transition was observed as the polymer concentration increased. The polymer predominantly formed micelles above 2.0 wt %. In the 2.0 wt % polymer solution, the mPEG-PTMC underwent spherical micelle-to-tubular nanostructure transition as the temperature increased from 10 to 40 degrees C, and the transition accompanied an increase in turbidity of the polymer aqueous solution due to the increase in the apparent size of the polymer aggregates. Here, we report that the morphology of vesicles, spherical micelles, and tubular nanostructures is reversibly controlled by a thermosensitive polymer of mPEG-PTMC and the variation of the morphology can be carefully traced by using cryo-TEM. This paper will not only provide an important method for morphological control of an amphiphilic polymer but also improve our understanding of a temperature-sensitive transition mechanism of the polymer.
Department of Chemistry, Division of Nano Sciences, Ewha Womans University, Daehyun-Dong, Seodaemun-Ku, Seoul, 120-750, Korea.
So Young
SY
Kim
Kyung Eun
KE
Lee
Sung Sik
SS
Han
Byeongmoon
B
Jeong
D020285:Cryoelectron Microscopy; D004146:Dioxanes / Q000737:chemistry*; D008823:Micelles; D046529:Microscopy, Electron, Transmission; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D011092:Polyethylene Glycols / Q000737:chemistry*
D004146:Dioxanes; D008823:Micelles; C515872:monomethoxy poly(ethylene glycol)-block-poly(trimethylene carbonate); D011092:Polyethylene Glycols