Abstract
The spatial distribution of bromine-labeled hydrophobic molecules—bromobenzene (BrBz) and 4-bromobenzylalcohol (BrBzOH)—incorporated in polymer micelles of poly(N,N-dimethylaminoethyl methacrylate)-block-poly(methyl methacrylate) (PDMAEMA-b-PMMA) was investigated using anomalous small-angle X-ray scattering (ASAXS) near the Br K-edge. Both BrBz and BrBzOH were miscible with PMMA at all concentrations. ASAXS analyses revealed that BrBzOH was homogeneously dispersed in the hydrophobic PMMA core of the PDMAEMA-b-PMMA micelle, whereas BrBz was excluded from the vicinity of the core–shell interface of the PMMA core. Because of its hydrophobicity, BrBz resisted contact with water penetrating the PMMA core. Inevitably, a BrBz depletion layer formed in the vicinity of the core–shell interface. Conversely, because BrBzOH has an affinity for water due to its hydroxyl group, it can exist even in the vicinity of the core–shell interface of the PMMA core. The results of the present study suggest that the spatial distribution of hydrophobic molecules in polymer micelles can be controlled by tuning the polarity of the encapsulated species.
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Acknowledgements
Generous financial support was provided by MEXT, Japan (Photon and Quantum Basic Research Coordinated Development Program). SAXS measurements were performed under the approval of the SPring-8 Advisory Committee (2012B1528, 2013B1277 and 2014B1419 for IA, 2013B1683 for MK and 2015A1331 for RN).
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Nakanishi, R., Machida, G., Kinoshita, M. et al. Anomalous small-angle X-ray scattering study on the spatial distribution of hydrophobic molecules in polymer micelles. Polym J 48, 801–806 (2016). https://doi.org/10.1038/pj.2016.32
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DOI: https://doi.org/10.1038/pj.2016.32
