Characterization of polymer micelles by the combination of SAXS and FFF-MALS

Abstract

Poly(ethylene glycol)-block-poly(partially benzyl-esterified aspartic acid), denoted by PEG-P(Asp(Bzl)), is one of the most examined blockcopolymers for drug carriers. However, little is known about its fundamental physical properties. Nine samples of PEG-P(Asp(Bzl)) with different benzylation fraction (7 Bzl) and aspartic chain length (DP Asp) were synthesized and the aggregation number (N agg), the core radius (R c) and other structural parameters were determined with a combination of light scattering and synchrotron X-ray small-angle scattering. The major factor to determine N agg and R c was found to be F Bzl, i.e., the hydrophobic nature of the core, even though F Bzl was changed in a relatively small composition range from 66-89 mol%. The overcrowding nature of the tethered PEG chains on the micelles increased about 1.5-3 times with increasing N agg compared with the unperturbed state in solutions. ©2012, The Society of Polymer Science, Japan.