Looped structure of flowerlike micelles revealed by (1)H NMR relaxometry and light scattering
| Autor: | de Graaf, A.J., Boere, K.W.M., Kemmink, J., Fokkink, R.G., van Nostrum, C.F., Rijkers, D.T.S., van de Gucht, J., Wienk, H.L.J., Baldus, M., Mastrobattista, E., Vermonden, T., Hennink, W.E., Advanced drug delivery systems/drug targeting, Biofysisch, Medicinal Chemistry and Chemical Biology, NMR Spectroscopy, Pharmaceutics, SYNTHESE, Sub Drug targeting, Dep Farmaceutische wetenschappen, Sub Medicinal Chemistry & Chemical biol., Sub NMR Spectroscopy, Faculteit Betawetenschappen |
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| Přispěvatelé: | Advanced drug delivery systems/drug targeting, Biofysisch, Medicinal Chemistry and Chemical Biology, NMR Spectroscopy, Pharmaceutics, SYNTHESE, Sub Drug targeting, Dep Farmaceutische wetenschappen, Sub Medicinal Chemistry & Chemical biol., Sub NMR Spectroscopy, Faculteit Betawetenschappen |
| Jazyk: | angličtina |
| Rok vydání: | 2011 |
| Předmět: |
aqueous-solution
triblock copolymer Materials science Magnetic Resonance Spectroscopy Light Laboratorium voor Fysische chemie en Kolloïdkunde nmr relaxation Biomedische technologie en medicijnen Micelle Farmacie/Biofarmaceutische wetenschappen (FARM) chemistry.chemical_compound Dynamic light scattering Amphiphile Polymer chemistry Electrochemistry Copolymer Medical technology Scattering Radiation General Materials Science aggregation behavior block-copolymer micelles Physical Chemistry and Colloid Science Spectroscopy Micelles VLAG Pharmacology Aggregation number poly(ethylene glycol) Atom-transfer radical-polymerization micellization Organic Chemistry Farmacie(FARM) Surfaces and Interfaces Nuclear magnetic resonance spectroscopy Condensed Matter Physics Organische Chemie drug-delivery Crystallography chemistry nanoparticles oxide) Ethylene glycol |
| Zdroj: | Langmuir 27 (2011) 16 Langmuir, 27(16), 9843-9848 Langmuir, 27(16), 9843. American Chemical Society : Division of Carbohydrate Chemistry |
| ISSN: | 0743-7463 |
| Popis: | We present experimental proof that so-called "flowerlike micelles" exist and that they have some distinctly different properties compared to their "starlike" counterparts. Amphiphilic AB diblock and BAB triblock copolymers consisting of poly(ethylene glycol) (PEG) as hydrophilic A block and thermosensitive poly(N-isopropylacrylamide) (pNIPAm) B block(s) were synthesized via atom transfer radical polymerization (ATRP). In aqueous solutions, both block copolymer types form micelles above the cloud point of pNIPAm. Static and dynamic light scattering measurements in combination with NMR relaxation experiments proved the existence of flowerlike micelles based on pNIPAm(16kDa)-PEG(4kDa)-pNIPAm(16kDa) which had a smaller radius and lower mass and aggregation number than starlike micelles based on mPEG(2kDa)-pNIPAm(16kDa). Furthermore, the PEG surface density was much lower for the flowerlike micelles, which we attribute to the looped configuration of the hydrophilic PEG block. (1)H NMR relaxation measurements showed biphasic T(2) relaxation for PEG, indicating rigid PEG segments close to the micelle core and more flexible distal segments. Even the flexible distal segments were shown to have a lower mobility in the flowerlike micelles compared to the starlike micelles, indicating strain due to loop formation. Taken together, it is demonstrated that self-assemblies of BAB triblock copolymers have their hydrophilic block in a looped conformation and thus indeed adopt a flowerlike conformation. |
| Databáze: | OpenAIRE |
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