Sandie Piogé

Sol–gel reversible metallo-supramolecular hydrogels based on a thermoresponsive double hydrophilic block copolymer

A well-defined poly(N,N-dimethylacrylamide)-b-poly(N-isopropylacrylamide-co-2-vinyl-4,4-dimethylazlactone) thermoresponsive double hydrophilic block copolymer bearing a terpyridine entity (Tpy-PDMA-b-P(NIPAM-co-VDM)) was synthesized by successive RAFT polymerizations. An amphiphilic macro-chain transfer agent bearing a terpyridine moiety (Tpy-PDMA-CTA) was synthesized and used for the preparation of a double hydrophilic block copolymer (Tpy-PDMA-b-P(NIPAM-co-VDM)) by RAFT dispersion polymerization. The RAFT dispersion polymerization of water-soluble monomers showed good control over the molar mass and dispersity, as characterized by size exclusion chromatography (SEC) and 1H-NMR spectroscopy. Complexation in the presence of metal ions (Fe2+) and self-assembly of the Tpy-PDMA-b-P(NIPAM-co-VDM) copolymer in diluted solution (0.5% w/v) were investigated. The formation of dynamic metallo-supramolecular flower-like micelles was demonstrated by UV-Vis spectrophotometry and dynamic light scattering (DLS). The effect of the addition of Fe2+ ions to a concentrated solution (8% w/v) of the Tpy-PDMA-b-P(NIPAM-co-VDM) copolymer at low temperature was investigated and the thermal profile of the metallic bis-terpyridine complex ([Fe(Tpy-PDMA-b-P(NIPAM-co-VDM))2]2+) has been studied by differential scanning calorimetry (DSC). The influence of temperature on the aqueous solution (8% w/v) of the ([Fe(Tpy-PDMA-b-P(NIPAM-co-VDM))2]2+) metallic complex was investigated by rotational rheometry. The results show that the self-assembly of the thermoresponsive block of the metallic bis-terpyridine complex formed a dynamic hydrogel with a sol–gel thermoreversible transition.

Poly(1,4-butadiene)-graft-poly(L-lactide) via the grafting-from strategy

Poly(1,4-butadiene)-graft-poly(L-lactide) copolymers were efficiently prepared via the grafting-from strategy using a combination of ring-opening metathesis polymerization (ROMP) of a hydroxyl-functionalized cyclobutene monomer and organocatalyzed ring-opening polymerization (ROP) of L-lactide. The copolymers were characterized by NMR, MALDI-TOF, SEC, TGA, and DSC demonstrating that well-defined polyester-grafted poly(1,4-butadiene) were obtained through the reported methodology.

Tuning the Molar Composition of “Charge-Shifting” Cationic Copolymers Based on 2-(N,N-Dimethylamino)Ethyl Acrylate and 2-(tert-Boc-Amino)Ethyl Acrylate

Copolymers of 2-(N,N-dimethylamino)ethyl acrylate (DMAEA) and 2-(tert-Boc-amino)ethyl acrylate (tBocAEA) are synthesized by reversible addition-fragmentation chain transfer polymerization in a controlled manner with defined molar masses and narrow molar masses distributions (Ð ≤ 1.17). Molar compositions of the P(DMAEA-co-tBocAEA) copolymers are assessed by means of 1 H NMR. A complete screening in molar composition is studied from 0% of DMAEA to 100% of DMAEA. Reactivity ratios of both comonomers are determined by the extended Kelen-Tüdos method (r DMAEA = 0.81 and rtBocAEA = 0.99).

The effect of metal ions on the viscoelastic properties of thermosensitive sol-to-gel reversible metallo-supramolecular hydrogels

Smart metallo-supramolecular hydrogels offer attractive possibilities to combine the properties of hydrogels with the self-assembly features offered by metal–ligand coordination. The preparation of metal-bis(terpyridine-poly(N,N-dimethylacrylamide)-b-poly(N-isopropylacrylamide)) ([M(Tpy-PDMA-b-PNIPAM)2]2+) complexes in aqueous media and their use for the elaboration of hydrogels by thermo-induced micellar aggregation is investigated in this study. The rheological behaviour suggested that the metal-bis complexes based on a copolymer having two distinct hydrophilic blocks self-assemble into flower-like micelles. Moreover, the control of the viscoelastic properties of the hydrogels is notably achieved via an appropriate choice of the nature and the molar equivalent composition of metal ions.