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Effect of Hydrophobicity of PEO–PPO–PEO Block Copolymers on Micellization and Solubilization of a Model Drug Nimesulide
Author(s) -
Parmar Arpan,
Yerramilli Usha,
Bahadur Pratap
Publication year - 2012
Publication title -
journal of surfactants and detergents
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.349
H-Index - 48
eISSN - 1558-9293
pISSN - 1097-3958
DOI - 10.1007/s11743-011-1308-x
Subject(s) - chemistry , micelle , ethylene oxide , solubility , propylene oxide , copolymer , differential scanning calorimetry , nimesulide , solubilization , micellar solutions , polymer chemistry , organic chemistry , aqueous solution , polymer , thermodynamics , biochemistry , physics
The present work explored the molecular implications governing the solubilization of a model drug nimesulide (NIM) in micelles of ethylene oxide‐propylene oxide (EO–PO) triblock copolymers. The aggregation behavior and solubilization studies on four copolymers each with the same mol mass of central PPO block equal to 2,250 and varying % PEO was examined by means of UV–VIS. Moreover, high‐sensitivity differential scanning calorimetry, and Fourier transform infrared spectrometry measurements were used to evaluate the critical micellization temperature. The solubilization at different temperatures (30, 37, 45 °C), pH (2 to 10) and in the presence of added sodium chloride (0–2 M) was monitored and the partition coefficient ( P ) and the free energy of solubilization (Δ G s o ) were calculated. The site of solubilization of NIM in micelles was also probed. The NIM solubility decreased with increases in the PEO molecular weight; the drug resides in the micelle core.