Research Field 4

Roos, A.H.. et. al. Soft Matter, 2021, 17, 7032-7037, https://doi.org/10.1039/D1SM00582K

We characterize temperature-dependent macroscopic and nanoscopic phase transitions and nanoscopic pre-transitions of water-soluble single chain nanoparticles (SCNPs). We analyze the temperature-dependent phase transitions of spin-labeled SCNPs by rigorous spectral simulations of series of multicomponent EPR-spectra that derive from the nanoinhomogeneities 1) that are due to the single-chain compartmentation in SCNPs and 2) the transformation upon temperature change due to the LCST behavior. Especially for one SCNP, we find an interesting behavior that we ascribe to properties of the nanosized inner core with continuous effects before and jump-like changes after the macroscopic thermal collapse, indicating highly efficient desolvation and compaction upon increase in temperature and aggregation of individual nanoparticles above the collapse temperature. Published with a permission of the Soft Matter 2021.

Chen, S., et al. Macromolecules 2018,51 (21), 8620-8628, DOI: https://doi.org/10.1021/acs.macromol.8b01624.

Polymeric ionic liquids (POILs) are important materials in the field of ionic liquid gating. Reversible addition–fragmentation chain-transfer polymerization (RAFT) technique is applied to prepare three imidazolium-based acrylates with different counterions. Polymerization rate increase in the order of BF₄^Θ < PF₆^Θ < N(Tf)₂^Θ. Copolymerization with a semifluorinated monomer 2,2,2-trifluoroethyl acrylate (TFEA) was successful. The morphology and size of such semifluorinated POILs reveals the aggregated nanoparticles from P(APMIN(Tf)₂–co-TFEA) due to the mesoscale organization of the ionic “multiplets”. Reproduced with permission. Copyright 2018©, American Chemical Society.

Chen, S., et al. Journal of Materials Chemistry C 2018,6 (30), 8242-8250, DOI: http://dx.doi.org/10.1039/C8TC01936C.

In this study, we investigate POILs as a gating material within a field-effect transistor, additionally describing their glassy dynamics and charge transport properties. The gating effects of these POILs are studied in detail, showing for the first time a reversible phase transition between thin films formed from the brownmillertite phase SrCoO_2.5 and the perovskite phase SrCoO₃ by use of such POILs. This is especially pronounced for POIL 1: P(APMIN(Tf)2) homopolymer displaying gate voltages (VG) of 3–4 V and a gating time of ∼4 h. Reproduced by permission of The Royal Society of Chemistry.

Osim, W., et al. Chemical Communications  2013,49 (81), 9311-9313, DOI: http://dx.doi.org/10.1039/C3CC45305G.

Highly dispersible MoS₂ nanoparticles have been prepared via surface-modification using a novel tetraethylene glycol-based ionic liquid containing a chelating moiety attached to the cation. The choice of the respective ligand enables the generation of highly dispersible MoS₂ nanoparticles with either polar, hydrophobic or “amphiphilic” surfaces, forming highly stable dispersions or microemulsions. Reproduced by permission of The Royal Society of Chemistry.

Stojanovic, A., et al. Journal of Materials Chemistry A 2013,1 (39), 12159-12169, DOI: http://dx.doi.org/10.1039/C3TA12646C.

A series of novel poly(isobutylene)-based stable ionic liquids (PIB-ILs) with strongly temperature dependent nano- and mesostructures is reported. Modifying both the anchored cation and anion as well as the molecular weight of the attached polymer chain, the nanostructure and the viscoelastic behavior of PIB-ILs can be engineered. All investigated PIB-ILs exhibited a defined nano- and mesoscale ordering at room temperature, whereas the nature of the anchored cation showed a strong impact on the temperature-dependence of the mesoscale-structure as well as on the flow behavior of PIB-ILs. Reproduced by permission of The Royal Society of Chemistry.

Zare, P., et al. Macromolecules2012,45 (4), 2074-2084, DOI: http://dx.doi.org/10.1021/ma202736g.

The IL polymers (poly(isobutylene)s) 3a?3c (PIB-ILs) were prepared by a combination of living carbocationic polymerization (LCCP) and subsequent “click” chemistry for attachment of methylimidazolium (3a), pyrrolidinium (3b), and triethylammonium cations (3c). All three investigated PIB-ILs exhibited pronounced nanostructural organization at room temperature depending strongly on the nature of the anchored cation. Reproduced with permission. Copyright 2012©, American Chemical Society.

Appiah, C., et al. Macromolecular Rapid Communications2016,37 (14), 1175-1180, DOI: http://dx.doi.org/10.1002/marc.201600020.

The formation and design of a hierarchically nanostructured poly(isobutylene)-based ionic liquid (PIB-ILs) is reported, displaying assembly into classical multiplets and an additional ordering of the aromatic counteranions. The morphology of PIB-ILs as well as its temperature-dependent behavior displays two different transition temperatures: one originating from ordering of micelles within a cylinder, and the second from cylinder–cylinder arrangement. Reproduced by permission. Copyright © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.