Comparison of micelles formed by amphiphilic poly(ethylene glycol)‐b‐poly(trimethylene carbonate) star block copolymers

Abstract

In this article, we describe the synthesis and solution properties of PEG-b-PTMC star block copolymers via ring-opening polymerization (ROP) of trimethylene carbonate (TMC) monomer initiated at the hydroxyl end group of the core PEG using HCl Et 2 O as a monomer activator. The ROP of TMC was performed to synthesize PEG-b-PTMC star block copolymers with one, two, four, and eight arms. The PEG-b-PTMC star block copolymers with same ratio of between hydrophobic PTMC and hydrophilic PEG segments were obtained in quantitative yield and exhibited monomodal GPC curves. The amphiphilic PEG-b-PTMC star block copolymers formed spherical micelles with a core-shell structure in an aqueous phase. The mean hydrodynamic diameters of the micelles increased from 17 to 194 nm with increasing arm number. As arm number increased, the critical micelle concentration (CMC) of the PEG-b-PTMC star block copolymers increased from 3.1 Â 10 À3 to 21.1 Â 10 À3 mg/mL but the partition equilibrium constant, which is an indicator of the hydrophobicity of the micelles of the PEG-b-PTMC star block copolymers in aqueous media, decreased from 4.44 Â 10 4 to 1.34 Â 10 4 .In conclusion, we confirmed that the PEG-b-PTMC star block copolymers form micelles and, hence, may be potential hydrophobic drug delivery vehicles.

Laser ablation in liquids: Applications in the synthesis of nanocrystals

“…As a result, the ablation rate will decrease with the water thickness increasing. Similarly, Kim and Lee [95] revealed that the liquid layer results in the reduction of ablation threshold and the enhancement of ablation yield. These results thus show that the high production can occur by the PLA in the confining liquid for both of thin films deposition and small particles synthesis.…”

“…Clearly, in the PLA in liquids, the plasma with high temperature, high pressure and high density can continuously etch the solid target at the plasma-solid interface to promote the total ablation rate as shown in Fig. 7(a) [92][93][94][95]. Zhu and co-workers reported the laser ablation rate of Si varies with the thickness of the water layer above the Si target when a 248 nm KrF excimer with pulse duration of 23 ns was used to ablate a single Si substrate.…”

Stimuli-Responsive InjectableIn situ-Forming Hydrogels for Regenerative Medicines

“…[275][276][277][278][279] Aqueous solutions of MPEG-PTMC also become in situ-forming hydrogels in response to temperature. The micellar aggregation of MPEG-PTMC has been confirmed with 13 C NMR, transmission electron microscopy, and DLS measurements.…”

Synthesis and characterization of a novel amphiphilic poly (ethylene glycol)–poly (ε-caprolactone) graft copolymers

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] PEO is widely used not only for its hydrophilicity and biocompatibility, but also for some properties of POE present in the materials modified by POE. [6] Among the investigated amphiphilic block copolymers, the biodegradable copolymers are of special interest.…”