Abstract
Amphiphilic triblock copolymer, poly(p-dioxanone-co-caprolactone)-block-poly(ethylene oxide)-block-poly(p-dioxanone-co-caprolactone) (PPDO-co-PCL-b-PEO-b-PPDO-co-PCL) was synthesized by ring opening polymerization (ROP) of p-dioxanone and ε-caprolactone initiated through the hydroxyl end of poly(ethylene glycol) (PEG) in the presence of stannous 2-ethyl hexanoate [Sn(oct)2] as a catalyst. Polymerization and structural features of the polymers were analyzed by different physicochemical techniques (GPC, 1H NMR, 13C NMR, FT-IR, DSC and TGA). The splitting of 1H NMR resonance at δ 2.3 and δ 4.1 ppm reveals the random copolymerization. Polymeric nanoparticles were prepared in phosphate buffer (pH 7.4) by co-solvent evaporation technique at room temperature (25 °C). Existence of hydrophobic domains as cores of the micelles were characterized by 1H NMR spectroscopy and further confirmed with fluorescence technique using pyrene as a probe. Critical micelle concentration (CMC) of the polymer in phosphate buffer (pH. 7.4) was decreased from 2.3 × 10-3 to 7.6 × 10-4 g/L with the fraction of PCL. Polymeric nanoparticles observed by atomic force microscopy (AFM) were uniform and spherical, with smooth textured of around 50-30 nm diameter. Dynamic light scattering (DLS) and electrophoretic light scattering (ELS) measurements showed a monodisperse size distribution of around 113-90 nm hydrodynamic diameters and negative zeta (ζ) potential (-4 to -14 mV), respectively. The investigations for the polymeric nanoparticles in aqueous medium showed that the composition of the hydrophobic segment of amphiphilic block copolymer makes a significant influence on its physicochemical characteristics.
Original language | English (US) |
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Pages (from-to) | 69-78 |
Number of pages | 10 |
Journal | Colloids and Surfaces A: Physicochemical and Engineering Aspects |
Volume | 292 |
Issue number | 1 |
DOIs | |
State | Published - Jan 5 2007 |
Keywords
- Biomaterials
- Block copolymers
- Micelles
- Nanoparticles
- Self-assembled
ASJC Scopus subject areas
- Colloid and Surface Chemistry
- Physical and Theoretical Chemistry