ABA Type Amphiphiles with Poly(2-benzhydryl-2-oxazine) Moieties : Synthesis, Characterization and Inverse Thermogelation

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Hahn , L , Kessler , L , Polzin , L , Fritze , L , Forster , S , Helten , H & Luxenhofer , R 2021 , ' ABA Type Amphiphiles with Poly(2-benzhydryl-2-oxazine) Moieties : Synthesis, Characterization and Inverse Thermogelation ' , Macromolecular Chemistry and Physics , vol. 222 , no. 17 , 2100114 . https://doi.org/10.1002/macp.202100114

Title: ABA Type Amphiphiles with Poly(2-benzhydryl-2-oxazine) Moieties : Synthesis, Characterization and Inverse Thermogelation
Author: Hahn, Lukas; Kessler, Larissa; Polzin, Lando; Fritze, Lars; Forster, Stefan; Helten, Holger; Luxenhofer, Robert
Contributor: University of Helsinki, Polymers
University of Helsinki, Helsinki Institute of Sustainability Science (HELSUS)
Date: 2021-09
Language: eng
Number of pages: 12
Belongs to series: Macromolecular Chemistry and Physics
ISSN: 1022-1352
URI: http://hdl.handle.net/10138/334334
Abstract: Thermoresponsive polymers are frequently involved in the development of materials for various applications. Here, polymers containing poly(2- benzhydryl-2-oxazine) (pBhOzi) repeating units are described for the first time. The homopolymer pBhOzi and an ABA type amphiphile comprising two flanking hydrophilic A blocks of poly(2-methyl-2-oxazoline) (pMeOx) and the hydrophobic aromatic pBhOzi central B block (pMeOx-b-pBhOzi-b-pMeOx) are synthesized and the latter is shown to exhibit inverse thermogelling properties at concentrations of 20 wt.% in water. This behavior stands in contrast to a homologue ABA amphiphile consisting of a central poly(2-benzhydryl-2-oxazoline) block (pMeOx-b-pBhOx-b-pMeOx). No inverse thermogelling is observed with this polymer even at 25 wt.%. For 25 wt.% pMeOx-b-pBhOzi-b-pMeOx, a surprisingly high storage modulus of approximate to 22 kPa and high values for the yield and flow points of 480 Pa and 1.3 kPa are obtained. Exceeding the yield point, pronounced shear thinning is observed. Interestingly, only little difference between self-assemblies of pMeOx-b-pBhOzi-b-pMeOx and pMeOx-b-pBhOx-b-pMeOx is observed by dynamic light scattering while transmission electron microscopy images suggest that the micelles of pMeOx-b-pBhOzi-b-pMeOx interact through their hydrophilic coronas, which is probably decisive for the gel formation. Overall, this study introduces new building blocks for poly(2-oxazoline) and poly(2-oxazine)-based self-assemblies, but additional studies will be needed to unravel the exact mechanism.
Subject: 116 Chemical sciences
inverse thermogels
physical hydrogels
poly(2-oxazine)
poly(2-oxazoline)
self-assembly
POLY(2-OXAZOLINE)
COPOLYMERS
ORGANIZATION
MORPHOLOGY
HYDROGEL
GRADIENT
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