Tuning biocompatible block copolymer micelles by varying solvent composition: Core/corona structure and solvent uptake
Block copolymer micelles enable the formation of widely tunable self-assembled structures in liquid phases, with applications ranging from drug delivery to personal care products to nanoreactors. In order to understand fundamental aspects of micelle assembly and dynamics, the structural properties a...
| Main Authors: | , , , , , , , , , , |
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| Format: | Journal article |
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American Chemical Society
2017
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| _version_ | 1826278894350630912 |
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| author | Cooksey, T Singh, A Le, K Wang, S Kelley, E He, L Vajjala Kesava, S Gomez, E Kidd, B Madsen, L Robertson, M |
| author_facet | Cooksey, T Singh, A Le, K Wang, S Kelley, E He, L Vajjala Kesava, S Gomez, E Kidd, B Madsen, L Robertson, M |
| author_sort | Cooksey, T |
| collection | OXFORD |
| description | Block copolymer micelles enable the formation of widely tunable self-assembled structures in liquid phases, with applications ranging from drug delivery to personal care products to nanoreactors. In order to understand fundamental aspects of micelle assembly and dynamics, the structural properties and solvent uptake of biocompatible poly(ethylene oxide-b-ϵ-caprolactone) (PEO-PCL) diblock copolymers in deuterated water (D2O)/tetrahydrofuran (THF-d8) mixtures were investigated with a combination of small-angle neutron scattering, nuclear magnetic resonance, and transmission electron microscopy. PEO-PCL block copolymers, of varying molecular weight yet constant block ratio, formed spherical micelles through a wide range of solvent compositions. Varying the solvent composition from 10 to 60 vol % THF-d8in D2O/THF-d8mixtures was a convenient means of varying the core-corona interfacial tension in the micelle system. An increase in THF-d8content in the bulk solvent increased the solvent uptake within the micelle core, which was comparable for the two series, irrespective of the polymer molecular weight. Whereas the smaller molecular weight micelle series exhibited a decrease in aggregation number with increasing THF-d8content in the bulk solvent, as anticipated due to changes in the core-corona interfacial tension, the aggregation number of the larger molecular weight series was surprisingly invariant with bulk solvent composition. Differences in the dependencies of the micelle size parameters (core radius and overall micelle radius) on the solvent composition originated from the differing trends in aggregation number for the two micelle series. Incorporation of the known unimer content determined from NMR (described in the companion paper), and directly accounting for impacts of solvent swelling of the micelle core on the neutron scattering length density of the core, allowed refinement of and increased confidence in extracted micelle parameters. In summary, the two micelle series showed similar solvent uptake that was independent of the polymer molecular weight yet significantly different dependencies of their aggregation number and size parameters on the solvent composition. |
| first_indexed | 2024-03-06T23:50:45Z |
| format | Journal article |
| id | oxford-uuid:7282b357-f6fb-4ef6-a50e-dd00f6eea94d |
| institution | University of Oxford |
| last_indexed | 2024-03-06T23:50:45Z |
| publishDate | 2017 |
| publisher | American Chemical Society |
| record_format | dspace |
| spelling | oxford-uuid:7282b357-f6fb-4ef6-a50e-dd00f6eea94d2022-03-26T19:50:37ZTuning biocompatible block copolymer micelles by varying solvent composition: Core/corona structure and solvent uptakeJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:7282b357-f6fb-4ef6-a50e-dd00f6eea94dSymplectic Elements at OxfordAmerican Chemical Society2017Cooksey, TSingh, ALe, KWang, SKelley, EHe, LVajjala Kesava, SGomez, EKidd, BMadsen, LRobertson, MBlock copolymer micelles enable the formation of widely tunable self-assembled structures in liquid phases, with applications ranging from drug delivery to personal care products to nanoreactors. In order to understand fundamental aspects of micelle assembly and dynamics, the structural properties and solvent uptake of biocompatible poly(ethylene oxide-b-ϵ-caprolactone) (PEO-PCL) diblock copolymers in deuterated water (D2O)/tetrahydrofuran (THF-d8) mixtures were investigated with a combination of small-angle neutron scattering, nuclear magnetic resonance, and transmission electron microscopy. PEO-PCL block copolymers, of varying molecular weight yet constant block ratio, formed spherical micelles through a wide range of solvent compositions. Varying the solvent composition from 10 to 60 vol % THF-d8in D2O/THF-d8mixtures was a convenient means of varying the core-corona interfacial tension in the micelle system. An increase in THF-d8content in the bulk solvent increased the solvent uptake within the micelle core, which was comparable for the two series, irrespective of the polymer molecular weight. Whereas the smaller molecular weight micelle series exhibited a decrease in aggregation number with increasing THF-d8content in the bulk solvent, as anticipated due to changes in the core-corona interfacial tension, the aggregation number of the larger molecular weight series was surprisingly invariant with bulk solvent composition. Differences in the dependencies of the micelle size parameters (core radius and overall micelle radius) on the solvent composition originated from the differing trends in aggregation number for the two micelle series. Incorporation of the known unimer content determined from NMR (described in the companion paper), and directly accounting for impacts of solvent swelling of the micelle core on the neutron scattering length density of the core, allowed refinement of and increased confidence in extracted micelle parameters. In summary, the two micelle series showed similar solvent uptake that was independent of the polymer molecular weight yet significantly different dependencies of their aggregation number and size parameters on the solvent composition. |
| spellingShingle | Cooksey, T Singh, A Le, K Wang, S Kelley, E He, L Vajjala Kesava, S Gomez, E Kidd, B Madsen, L Robertson, M Tuning biocompatible block copolymer micelles by varying solvent composition: Core/corona structure and solvent uptake |
| title | Tuning biocompatible block copolymer micelles by varying solvent composition: Core/corona structure and solvent uptake |
| title_full | Tuning biocompatible block copolymer micelles by varying solvent composition: Core/corona structure and solvent uptake |
| title_fullStr | Tuning biocompatible block copolymer micelles by varying solvent composition: Core/corona structure and solvent uptake |
| title_full_unstemmed | Tuning biocompatible block copolymer micelles by varying solvent composition: Core/corona structure and solvent uptake |
| title_short | Tuning biocompatible block copolymer micelles by varying solvent composition: Core/corona structure and solvent uptake |
| title_sort | tuning biocompatible block copolymer micelles by varying solvent composition core corona structure and solvent uptake |
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