Hierarchical Sol–Gel Transition Induced by Thermosensitive Self-Assembly of an ABC Triblock Polymer in an Ionic Liquid

Abstract

We investigated a hierarchical morphology change and accompanying sol−gel transition using a doubly thermosensitive ABC-triblock copolymer in an ionic liquid (IL). The triblock copolymer contains two different lower critical solution temperature (LCST) thermosensitive polymers, poly(benzyl methacrylate) (PBnMA) and poly(2-phenylethyl methacrylate) (PPhEt-MA), as the end blocks and poly(methyl methacrylate) (PMMA) as the middle block (PBnMA-b-PMMA-b-PPhEtMA: BMP). BMP undergoes a hierarchical phase transition corresponding to the selfassembly of each of the thermosensitive blocks in the IL, and a sol−gel transition was observed in concentrated, above 10 wt %, polymer solutions. The gelation behavior was affected by polymer concentration, and at 20 wt %, the BMP/IL composite showed a phase transition, with increasing temperature, from solution through a jammed micelle suspension to a physically cross-linked gel. Each phase was formed reversibly and rapidly over the corresponding temperature range. The jammed micelle and cross-linked gel states were characterized using viscoelastic measurements and small-angle X-ray scattering (SAXS).

Macroscopic Adhesion of Thermoreversible ABC Triblock Copolymer‐Based Hydrogels Via Boronic Acid–Sugar Complexation

“…This implies that the ABC architecture gave an effective micellar network structure as expected . Dynamic strain sweep measurements also demonstrate that the prepared hydrogels maintained their strain resistance up to about 150% for both ABC‐LBA and ABC‐PBA, suggesting that the block copolymer micelles were not jammed in the solution but formed a robust polymer network (Figure S2, Supporting Information) . The change in the elastic moduli arises from the pulling‐out of the core‐forming blocks from the cross‐linking points.…”

Design and Materialization of Ionic Liquids Based on an Understanding of Their Fundamental Properties

“…11). These findings open up the possibility of stimuli-responsive molecular assemblies, [135][136][137] volume-phase transitions of ion gels, 128 and temperature-induced sol/gel transitions [138][139][140] in ILs. Recently, stimuli-responsiveness has expanded to include photo-stimuli using photochromic compounds, [141][142][143][144][145][146] and photo-healing materials 147,148 have been proposed.…”

Viscoelasticity of a Supramolecular Polymer Network and its Relevance for Enhanced Oil Recovery

“…ΔG,' ΔG", and Δ|η*|increase by more than an order of magnitude relative to the baseline of the HPAM and AP polymers at the same ω = 7.055 rad/s. Furthermore, the low loss factor, tanδ < 1, with G' > G" in the entire range of angular frequency; corresponds to a flow behavior that is characteristic of stable dispersions in the form of network-like structures built up through inter-and intramolecular interactions [3,9,45,[47][48][49][50][51]. Furthermore, the storage modulus, G', kept increasing at high angular frequencies, which "[verifies] the dynamic nature of the bonds within the network" [5].…”