TY - JOUR
T1 - ABC block copolymer micelles driving the thermogelation
T2 - Scattering, imaging and spectroscopy
AU - Constantinou, Anna P.
AU - Nele, Valeria
AU - Doutch, James j.
AU - Shmool, Talia a.
AU - Wang, Shaobai
AU - Li, Qian
AU - Hallett, Jason P.
AU - Dreiss, Cécile A.
AU - Stevens, Molly M.
AU - Georgiou, Theoni K.
N1 - Funding Information:
We gratefully acknowledge Dr Saskia Bakker at the University of Warwick Advanced Bioimaging Research Technology Platform (supported by BBSRC ALERT14 award BB/M01228X/1) for performing the cryo-TEM. A.P.C. acknowledges the Engineering and Physical Sciences Research Council (EPSRC) for the Doctoral Prize Fellowship (EP/M506345/1) as well as the EPSRC Impact Acceleration Grant EP/R511547/1, which has been awarded to TKG\u2019s group. V.N. acknowledges the Ermenegildo Zegna Founder\u2019s Scholarship program. V.N. and M.M.S. acknowledge funding from the Rosetrees Trust. The SANS experiments were performed at the ISIS Neutron and Muon Source at the STFC Rutherford Appleton Laboratory, UK, and they were supported by a beamtime allocation from the Science and Technology Facilities Council (1910285). The SANS analysis has been carried out using the SasView software, which was originally developed under the NSF award DMR-0520547. The software contains code the development of which was funded by the European Union\u2019s Horizon 2020 research and innovation programme under the SINE2020 project, grant agreement 654000. Mr Bernard Chan is acknowledged for assisting with part of the analysis during his MEng project.
Funding Information:
Pluronic F127 solutions at 1 and 5 w/w% showed similar CD spectra with the negative bands attributed to the n\u2212\u03C0* and \u03C0\u2212\u03C0* of the asymmetric carbon in its PG unit, forming the central thermoresponsive block [45\u201347]. Notably, the Pluronic F127 samples exhibited minimal changes in MRE with increasing temperature, consistent with the previous results. More specifically, Pluronic F127 solutions at the concentrations studied remain transparent runny solutions upon heating, with the self-assembled structures minimally affected by these temperature and concentration changes, as supported by SANS and TEM analysis.
Publisher Copyright:
© 2024 The Authors
PY - 2024/5/16
Y1 - 2024/5/16
N2 - Thermoresponsive polymers have attracted much scientific attention due to their capacity for temperature-driven hydrogel formation. For biomedical applications, such as drug delivery, this transition should be tuned below body temperature to facilitate controlled and targeted drug release. We have recently developed a thermoresponsive polymer that forms gel at low concentrations (2 w/w%) in aqueous media and offers a cost-effective alternative to thermoresponsive systems currently being applied in clinics. This polymer is an ABC triblock terpolymer, where A, B, and C correspond to oligo(ethylene glycol) methyl ether methacrylate with average Mn 300 g mol−1 (OEGMA300), n-butyl methacrylate (BuMA), and di(ethylene glycol) methyl ether methacrylate (DEGMA). To investigate the self-assembly and the gelation mechanism in diluted solutions, we used small-angle neutron scattering (SANS) on 1 w/w% (below the gelation concentration) and 5 w/w% solutions (above the gelation concentration). As a comparison, we also investigated the solutions of the most studied thermoresponsive polymer, namely, Pluronic F127, an ABA triblock bipolymer made of ethylene glycol (A) and propylene glycol (B) blocks. SANS revealed that the in-house synthesised polymer forms elliptical cylinders, whose length increases significantly with temperature. In contrast, Pluronic F127 solutions form core-shell spherical micelles, which slightly elongate with temperature. Transmission electron microscopy images support the SANS findings, with tubular/worm structures being present. Variable-temperature circular dichroism (CD) and proton nuclear magnetic resonance (1H NMR) spectroscopy experiments reveal insights on the tacticity, structural changes, and molecular origin of the self-assembly.
AB - Thermoresponsive polymers have attracted much scientific attention due to their capacity for temperature-driven hydrogel formation. For biomedical applications, such as drug delivery, this transition should be tuned below body temperature to facilitate controlled and targeted drug release. We have recently developed a thermoresponsive polymer that forms gel at low concentrations (2 w/w%) in aqueous media and offers a cost-effective alternative to thermoresponsive systems currently being applied in clinics. This polymer is an ABC triblock terpolymer, where A, B, and C correspond to oligo(ethylene glycol) methyl ether methacrylate with average Mn 300 g mol−1 (OEGMA300), n-butyl methacrylate (BuMA), and di(ethylene glycol) methyl ether methacrylate (DEGMA). To investigate the self-assembly and the gelation mechanism in diluted solutions, we used small-angle neutron scattering (SANS) on 1 w/w% (below the gelation concentration) and 5 w/w% solutions (above the gelation concentration). As a comparison, we also investigated the solutions of the most studied thermoresponsive polymer, namely, Pluronic F127, an ABA triblock bipolymer made of ethylene glycol (A) and propylene glycol (B) blocks. SANS revealed that the in-house synthesised polymer forms elliptical cylinders, whose length increases significantly with temperature. In contrast, Pluronic F127 solutions form core-shell spherical micelles, which slightly elongate with temperature. Transmission electron microscopy images support the SANS findings, with tubular/worm structures being present. Variable-temperature circular dichroism (CD) and proton nuclear magnetic resonance (1H NMR) spectroscopy experiments reveal insights on the tacticity, structural changes, and molecular origin of the self-assembly.
UR - http://www.scopus.com/inward/record.url?scp=85191583658&partnerID=8YFLogxK
U2 - 10.1016/j.polymer.2024.127075
DO - 10.1016/j.polymer.2024.127075
M3 - Article
SN - 0032-3861
VL - 302
JO - Polymer
JF - Polymer
M1 - 127075
ER -