The formation of micelle self-assembled from hydrophobically end-capped poly(ethylene oxide) (PEO) and its application for drug delivery have been investigated. As an important ABA-type associative triblock copolymer, a series of hydrophobically end-capped poly(ethylene oxide) [H(CH 2 ) n O(CH 2 CH 2 O) m (CH 2 ) n H], consisting of PEO (B) as hydrophilic segment and alkyl groups as hydrophobic block, are synthesized successfully according to 1 H NMR, Fourier transform infrared (FTIR), and differential scanning calorimetry (DSC) measurements. The triblock polymer is easy to form aggregates (micelles) under the appropriate conditions. The morphologies of micelles are found to be spherical confirmed by atomic force microscopy (AFM) measurement. Then, the polymeric micelles self-assembled from the triblock copolymer are used as a nanocarrier to solubilize poorly water-soluble drug spironolactone (a typical hydrophobicity drug). In vitro release behavior of spironolactone from triblock copolymer micelle is investigated carefully. It indicates interestingly that the drug can be released from triblock copolymer micelle stably and the release rate can be modulated by the variation of copolymer composition.
The breath figure method has emerged as a new self-assembly technique to fabricate ordered porous materials, which show potential applications in many fields, such as size-selective separation membranes. However, it is challenging to customize the structures, especially to precisely tune the pore size in a wide range. Moreover, the relationship between polymer structure and film morphologies is still unknown. In this paper, we report a facile, effective, and controllable way to manipulate the evolution of morphologies of honeycomb films, which is based on the blends of an amphiphilic block copolymer and polystyrenes with hydrophobic end groups. A series of atom transfer radical polymerization (ATRP) initiators with alkyl or fluorinated groups were synthesized for polystyrenes with hydrophobic end groups. Polymerization kinetics confirmed the viability of these ATRP initiators. Surface segregation behaviors of the hydrophobic end groups were demonstrated by measuring the surface chemical composition and surface free energies. We found that the polystyrenes with hydrophobic end groups form ordered films only at high polymer concentration (40–60 mg mL−1); moreover, the use of blends of two types of polystyrenes, one of which has a hydrophobic end group whereas the other has a hydrophilic block, can greatly increase the regularity of the honeycomb films and provide the possibility to fine-tune the pore diameter. Moreover, the evolution of surface morphologies of the films can be ideally correlated with the surface free energies of the end-functionalized polymers.
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