Dynamics and Structural Behavior of Nanocomposite Hydrogel by using Rod-like Particles

Abstract

Dynamics and structural behavior of nanocomposite hydrogel by using rod-like particles been explored. Polymer solutions, polymer gels and nanocomposite gels containing rod-like particles have been probed by using dynamic light scattering, small angle neutron scattering and small angle X-ray scattering. Thermoresponsive polymer, Poly(2-((3-(1-(2-(dimethylamino)ethyl)-1H-1,2,3-triazol-4-yl)propanoyl)oxy)ethyl methacrylate), exhibits temperature dependent clustering. The thermal variation of hydrodynamic radius of clusters has taken into account for the formation of transient network and shrinking behavior of clusters during clustering. The cluster structure was observed as the resultant from hydrophobic attraction allowing the increase in fractal dimensionality. The clustering is influenced by the chain conformation and solution quality (Chapter 2). The structure of poly(ethylene oxide) gel has been investigated. The dried hydrogel film consists of lamellae and amorphous crosslinked chains. The contribution of crystalline to the reinforcement has been revealed by probing the structural behavior under deformation. The lamellae release into the amorphous network when the gel films are swollen. The polymer chains in the confined network exhibit reversible behaviors as the interactive system (Chapter 3). The gelation and dynamics of imogolite-poly(acrylic acid) nanocomposite hydrogel have been investigated. The nanocomposite gels were prepared from the imogolite, rod-like particle, irradiated by γ-ray. The time resolved light scattering was performed at the reaction temperature. The gelation process has been observed as three stages: diffusion of imogolite, clustering with the polymerization, gel threshold and complete gels. The complete gels were investigated by ensemble averaged light scattering. The results showed the collective diffusion of characteristic chain behavior and slow fluctuations via inhomogeneities depending on imogolite concentration (Chapter 4). The static structure of the imogolite-poly(acrylic acid) hydrogel has been observed using small angle neutron scattering and X-ray scattering in terms of the imogolite concentration and magnitude of deformation. X-ray provided imogolite scattering as the contrast matching condition, and neutron allowed the polymer dominant results. The imogolite exists as aggregates with the overlaps of rods. The orientation of the imogolite, the size variation of overlaps and the change of dimensionality of gels were observed, and the results describe the role of imogolite as a reinforcing fillers. The structure of the imogolite bundles responds to the external deformations as the imogolite rods are align and overlapped. (Chapter 5).