Ingrid Verbruggen

HRMAS 1H NMR as a tool for the study of supramolecular gels

HRMAS 1H NMR is reported for the first time as a useful technique to gain insight into the dynamic properties of aggregates present in supramolecular gels. The study of several low molecular weight gelators with this technique in toluene and acetonitrile is described.

Guanidine-based polycarbonate hydrogels: from metal-free ring-opening polymerization to reversible self-assembling properties

Bio-inspired stabilization of aliphatic polycarbonate-based hydrogels has been carried out by the metal-free ring-opening co-polymerization (ROP) of 6-membered cyclic carbonates containing, respectively, protected guanidine and carboxylic acid functions. Polyethylene glycol (PEG) bound to methylcarboxy trimethylene carbonate at each extremity was used as the cross-linker, and the copolymerizations were performed in CH2Cl2 for 24 h in the presence of 1,8-diazabicyclo[5.4.0]-undec-7-ene (DBU) and N-(3,5-trifluoromethyl)phenyl-N′-cyclohexylthiourea (TU), the catalyst and co-catalyst, respectively. Well-defined hydrogels of various compositions and presenting a high gel fraction were obtained. HR-MAS NMR has been successfully employed to validate our purification technique as well as to assess the selective de-protection of the guanidine and carboxylic acid functions. Evidence of self-assembling properties has been attested by differential scanning calorimetry (DSC), HR-MAS NMR analysis and swelling test experiments in aqueous buffered solutions at pH 4 and 8.

In situ evaluation of interfacial affinity in CeO2 based hybrid nanoparticles by pulsed field gradient NMR

Complexation affinity of laurate ligands (C(12)H(23)O(2)) grafted onto the surface of cerium(IV) oxide nanoparticles can be probed and quantified in situ, by pulsed field gradient (1)H NMR through the dependence of the diffusion coefficient on the size of a species.