Mediating Gel Formation from Structurally Controlled Poly(Electrolytes) Through Multiple “Head-to-Body” Electrostatic Interactions

Abstract

Tuning the chain-end functionality of a short-chain cationic homopolymer, owing to the nature of the initiator used in the atom transfer radical polymerization (ATRP) polymerization step, can be used to mediate the formation of a gel of this poly(electrolyte) in water. While a neutral end group gives a solution of low viscosity, a highly homogeneous gel is obtained with a phosphonate anionic moiety, as characterized by rheometry and diffusion nuclear magnetic resonance (NMR). This novel type of supramolecular control over poly(electrolytic) gel formation could find potential use in a variety of applications in the field of electro-active materials.

Ion pairing controls rheological properties of “processionary” polyelectrolyte hydrogels

“…For fluoride counterions as well as PIm + Cl -, the rheological profile is that of pure water which confirms the visual observation. However all other samples behave as shear-thinning yield stress fluids, confirming our previous results with PIm + Br - [24]. As shown in Figure 4, soluble samples are solid-like (G G ) at small strain and flow at large strains (G G ) with a steep decrease of the moduli.…”

“…We have previously demonstrated that, due to the opposite charges of the phosphonate head, head-to-body ionic bonds are possible [24]. On the one hand, if at least two foreign heads attach to the same body, we obtain an effective cross-link point.…”

“…We synthesise the phosphonate terminated polymer hereafter referred to as PBr according to our previously reported methodology [24,26]. We obtain a wellcontrolled linear polymer (M w = 8200 Da from NMR, 5614 Da from GPC with M w /M n = 1.08; see Supplementary Materials and Supplementary Figure S1), with a degree of polymerisation N 0 = 70 (NMR).…”

“…We have recently reported on a highly reversible poly(cation) based hydrogel [24], which formation relies on a new concept of supramolecular electrostatic interaction. Briefly, the atom transfer radical polymerisation (ATRP) is initiated by a phosphonateterminated ATRP initiator, eventually affording an anion-terminated poly(cationic) polymer.…”

Interactions of a biocompatible water-soluble anthracenyl polymer derivative with double-stranded DNA

“…This result could be expected with regard to the neutral nature of the polymer chain, which limits the interaction with anionic phosphate substituents; conversely, this suggests that substituting the pendant neutral group on the polymer side chain by cationic moieties could be a relevant strategy in order to enhance binding affinities of fluorescent probes for DNA. 91…”