ABSTRACT
Silanized hydroxypropyl methylcellulose based hydrogels were developed for cartilage and intervertebral disc tissue engineering. Herein, study of dynamics of confined water showed two different populations, identified as hydration and bulk-like water. The diffusion coefficient showed that bulk-like water diffuses over distances â¼10 µm without being affected by the hydrogel matrix. Addition of silica nanofibers leads to improved mechanical properties and enhanced diffusion coefficient. Good diffusion within hydrogels is essential for the application.
Subject(s)
Hydrogels/chemistry , Hypromellose Derivatives/chemistry , Thermodynamics , Tissue Engineering , Water/chemistry , Hydrogels/chemical synthesis , Particle Size , Surface PropertiesABSTRACT
Ionogels based on in situ crosslinking of chitosan in the ionic liquid 1-ethyl-3-methylimidazolium acetate (EMIm Ac) are synthesized, and studied from macroscopic properties to preferred interactions at the host matrix/EMIm Ac interface. It is highlighted that the imidazolium cations of the ionic liquid (IL) show preferred interactions with the chitosan host matrix. This exemplifies how the confinement of ILs, through an interface effect, can induce the breakdown of aggregated regions found systematically in bulk ILs and can increase the fragility of ILs. These biopolymer based ionogels could find application as biosensors and in the field of energy.
ABSTRACT
Confining ionic liquids (ILs) with added lithium salt within silica host networks enhances their fragility and improves their conductivity. Overall, conductivity measurements, Raman spectroscopy of the TFSI anion and NMR spectroscopy of the lithium cation show segregative interaction of lithium ions with the SiO2 host matrix. This implies at IL/SiO2 interfaces a breakdown of aggregated regions that are found systematically in bulk ILs. Such destructuration due to the interface effect determines the fragility and thus results locally at the interface in short relaxation times, low viscosity, and good ionic conductivity. The "destructuration" of ion pairs or domains makes ILs within ionogels a competitive alternative to existing solid ionic conductors in all-solid devices, such as lithium batteries and supercapacitors.
ABSTRACT
(1)H MAS NMR and temperature-dependent relaxation time measurements were carried out for the first time on ionic liquids confined in monolithic silica matrices and enabled us to show that the ionic liquids' dynamics experienced only a very small slowing-down. The confinement preserved the ionic liquids' properties and, moreover, allowed liquid-like behaviour at temperatures below the crystallisation temperature of genuine ionic liquids. This study highlights the interest of the ionogel approach to all-solid state devices with genuine IL properties.
