Polyethylene oxide (PEO) end-capped with cholesterol (Chol-PEO-Chol) has been used as linkers in order to form interconnected network (gel) for biomedeical applications. In this presentation, we will demonstrate that Chol-PEO-Chol forms flower-like micelle, which is confirmed by combination of experimental methods and molecular dynamic simulations. The critical micelle concentrations of the polymers increase with the molecular weight of PEO as determined by fluorescence spectroscopy and dynamic light scattering. The overall size and internal structure of such micelles were also determined through dynamic light scattering, small angle neutron and X-ray scattering. The small angle scattering data were simultaneously fitted with a core-two-shell model, revealing a nearly dry cholesterol core, an inner and outer shell of PEO with approximately 50% and 88% of water content, respectively. The dimension and water contents are consistent with the MD simulation outcomes, validating the formation of flower-like micelles. In case of 10k and 20k, coexistence of unimers and flower-like micelles are found presumably due to an increase in the hydrophilicity of the Chol-PEO-Chol. Lastly, aggregation number (N<sub>agg</sub>) of micelles are estimated to be practically invariant with respect to the molecular weight of PEO.

Micellar structure of the hydrophobically modified polyethylene oxide (PEO): A combinational study of scattering and molecular dynamic simulations

ACS Spring 2022

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