Abstract
Amphiphilic diblock copolymers were synthesized based on poly(2-ethyl-2-oxazoline) (PEtOz) as a hydrophilic block and aliphatic polyesters such as poly(L-lactide) (PLA) or poly(ε-caprolactone) (PCL) as a hydrophobic block. Their micellar characteristics in an aqueous phase were investigated by using dynamic light scattering and fluorescence techniques. The block copolymers formed micelles in the aqueous phase with critical micelle concentrations (cmcs) in the range of 1.0-8.1 mg/L. The cmc values become lower upon increasing the length of the hydrophobic block. The mean diameter of the micelles were in the range of 108-192 nm, with a narrow distribution. In general, the micelle size increased as the hydrophobic PLA or PCL block became larger. The partition equilibrium constants, Kv, of pyrene in the micellar solutions of the block copolymers were from 1.79 × 105 to 5.88 × 105. For each block copolymer system of PEtOz-PLA or PEtOz-PCL, the Kv value increased as the length of the hydrophobic block increased. The steady-state fluorescence anisotropy values (r) of 1,6-diphenyl-1,3,5-hexatriene (DPH) were 0.265-0.284 in PEtOz-PLA solution and 0.189-0.196 in PEtOz-PCL solution. The anisotropy values of PEtOz-PLAs were higher than those of PEtOz-PCLs. The anisotropy values were independent of the length of the hydrophobic block when the chemical structures of the hydrophobic blocks were identical. The micelles underwent hydrogen bonding at pH <3.5 with poly(acrylic acid), which produced polymer complex precipitates that could be reversibly dispersed as micelles at pH >3.8.
| Original language | English |
|---|---|
| Pages (from-to) | 1847-1852 |
| Number of pages | 6 |
| Journal | Macromolecules |
| Volume | 32 |
| Issue number | 6 |
| DOIs | |
| Publication status | Published - 1999 Mar 23 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Materials Chemistry
Cite this
Synthesis and micellar characterization of amphiphilic diblock copolymers based on poly(2-ethyl-2-oxazoline) and aliphatic polyesters. / Lee, Sang Cheon; Chang, Youngkyu; Yoon, Jin San; Kim, Chulhee; Kwon, Ick Chan; Kim, Yong Hee; Jeong, Seo Young.
In: Macromolecules, Vol. 32, No. 6, 23.03.1999, p. 1847-1852.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Synthesis and micellar characterization of amphiphilic diblock copolymers based on poly(2-ethyl-2-oxazoline) and aliphatic polyesters
AU - Lee, Sang Cheon
AU - Chang, Youngkyu
AU - Yoon, Jin San
AU - Kim, Chulhee
AU - Kwon, Ick Chan
AU - Kim, Yong Hee
AU - Jeong, Seo Young
PY - 1999/3/23
Y1 - 1999/3/23
N2 - Amphiphilic diblock copolymers were synthesized based on poly(2-ethyl-2-oxazoline) (PEtOz) as a hydrophilic block and aliphatic polyesters such as poly(L-lactide) (PLA) or poly(ε-caprolactone) (PCL) as a hydrophobic block. Their micellar characteristics in an aqueous phase were investigated by using dynamic light scattering and fluorescence techniques. The block copolymers formed micelles in the aqueous phase with critical micelle concentrations (cmcs) in the range of 1.0-8.1 mg/L. The cmc values become lower upon increasing the length of the hydrophobic block. The mean diameter of the micelles were in the range of 108-192 nm, with a narrow distribution. In general, the micelle size increased as the hydrophobic PLA or PCL block became larger. The partition equilibrium constants, Kv, of pyrene in the micellar solutions of the block copolymers were from 1.79 × 105 to 5.88 × 105. For each block copolymer system of PEtOz-PLA or PEtOz-PCL, the Kv value increased as the length of the hydrophobic block increased. The steady-state fluorescence anisotropy values (r) of 1,6-diphenyl-1,3,5-hexatriene (DPH) were 0.265-0.284 in PEtOz-PLA solution and 0.189-0.196 in PEtOz-PCL solution. The anisotropy values of PEtOz-PLAs were higher than those of PEtOz-PCLs. The anisotropy values were independent of the length of the hydrophobic block when the chemical structures of the hydrophobic blocks were identical. The micelles underwent hydrogen bonding at pH <3.5 with poly(acrylic acid), which produced polymer complex precipitates that could be reversibly dispersed as micelles at pH >3.8.
AB - Amphiphilic diblock copolymers were synthesized based on poly(2-ethyl-2-oxazoline) (PEtOz) as a hydrophilic block and aliphatic polyesters such as poly(L-lactide) (PLA) or poly(ε-caprolactone) (PCL) as a hydrophobic block. Their micellar characteristics in an aqueous phase were investigated by using dynamic light scattering and fluorescence techniques. The block copolymers formed micelles in the aqueous phase with critical micelle concentrations (cmcs) in the range of 1.0-8.1 mg/L. The cmc values become lower upon increasing the length of the hydrophobic block. The mean diameter of the micelles were in the range of 108-192 nm, with a narrow distribution. In general, the micelle size increased as the hydrophobic PLA or PCL block became larger. The partition equilibrium constants, Kv, of pyrene in the micellar solutions of the block copolymers were from 1.79 × 105 to 5.88 × 105. For each block copolymer system of PEtOz-PLA or PEtOz-PCL, the Kv value increased as the length of the hydrophobic block increased. The steady-state fluorescence anisotropy values (r) of 1,6-diphenyl-1,3,5-hexatriene (DPH) were 0.265-0.284 in PEtOz-PLA solution and 0.189-0.196 in PEtOz-PCL solution. The anisotropy values of PEtOz-PLAs were higher than those of PEtOz-PCLs. The anisotropy values were independent of the length of the hydrophobic block when the chemical structures of the hydrophobic blocks were identical. The micelles underwent hydrogen bonding at pH <3.5 with poly(acrylic acid), which produced polymer complex precipitates that could be reversibly dispersed as micelles at pH >3.8.
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U2 - 10.1021/ma981664k
DO - 10.1021/ma981664k
M3 - Article
AN - SCOPUS:0032650468
VL - 32
SP - 1847
EP - 1852
JO - Macromolecules
JF - Macromolecules
SN - 0024-9297
IS - 6
ER -