Thermoresponsive Polymer Ionic Liquids and Nanostructured Hydrogels Based upon Amphiphilic Polyisobutylene-b-poly(2-ethyl-2-oxazoline) Diblock Copolymers

Benjamin Kerscher, Tobias M. Trötschler, Balázs Pásztói, Saskia Gröer, Ákos Szabó, B. Iván, Rolf Mülhaupt

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5 Citations (Scopus)

Abstract

The precise molecular engineering of amphiphilic diblock copolymers as thermoresponsive polymer ionic liquids (PILs) couples polyisobutylene (PIB) and poly(2-ethyl-2-oxazoline) (PEtOx) blocks via an imidazolium cation. It enables thermal switching of micellar self-assembly and yields nanostructured hydrogels. Just one ionic liquid (IL)-type imidazolium cation is readily incorporated into the backbone of the PIB-IL-PEtOx block copolymers by terminating the cationic 2-ethyl-2-oxazoline (EtOx) ring-opening polymerization by alkylation of an imidazole-terminated PIB. The PEtOx block length varies as a function of the PIB-imidazole/EtOx molar ratio and governs solubility, hydrophilic/hydrophobic balance, and nanophase separation. In spite of the presence of highly hydrophobic PIB segments, PIB-IL-PEtOx are rendered water soluble with increasing PEtOx block length and form spherical and elongated micelles as well as hydrogels exhibiting wormlike nanostructures. Furthermore, the lower critical solution temperature of PEtOx segments is the key to thermoresponsive behavior of both water-soluble copolymers and copolymer hydrogels. Owing to low glass temperature and high stability of PIB, these PIB-PILs represent attractive macromolecular nanosystems enabling thermal switching of solubilization, dispersion, transport, and shuttling of molecules and nanoparticles.

Original languageEnglish
Pages (from-to)3306-3318
Number of pages13
JournalMacromolecules
Volume52
Issue number9
DOIs
Publication statusPublished - May 14 2019

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ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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