Synthesis, characterization and surfactant properties of cholic acid containing linear and star polymers

Surface-active linear and star-shaped miktoarm polymers containing cholic acid as a bile acid derivative are prepared by esterification of poly(ethylene glycol methyl ether) and subsequent ring-opening polymerization of epsilon caprolactone, respectively. The chemical structures, molecular characteristics and thermal properties of obtained polymers are clearly confirmed by FT-IR, 1H-NMR, GPC, DSC and TGA analysis. The presence of characteristic bands of cholic acid, ether and ester groups in FT-IR and 1H-NMR spectroscopies is proof of the successful synthesis of linear and star-shaped polymers. The melting point of star-shaped polymer is slightly lower than the linear polymer. Additionally, their surface activity properties have been investigated by AFM, SEM and contact angle studies and it is found that they can be self-assembled into micelles. Furthermore, the size of the micelles and contact angle properties has been changed with the addition of both hydrophilic (poly(ethylene glycol)) and hydrophobic (poly(epsilon caprolactone)) blocks on the cholic acid head. It is also clearly seen the effect of hydrophobic poly(epsilon caprolactone) functions increased contact angle and surface tension values after the formation of star-shaped polymer.