The sol–gel method remains an attractive approach for dispersing an inorganic component in a polymer matrix on the mesoscopic scale. However, the interaction of inorganic components with polymer side chains increases uncontrolled crosslinking points and brings about the fatal loss of toughness in polymer materials. In this study, we report the use of tetrabutylphosphonium chloride (TBPC) as an ionic liquid to intercept interaction between polymethylmethacrylate (PMMA) and titania. The addition of TBPC to the PMMA/titania hybrid system is shown to improve transparency, toughness, and shape memory properties (SMPs). A tensile test showed that the hybrid system containing 40 wt% TBPC had a breaking energy (362.1 kJ m⁻³) that was ∼28 times greater than that of the film without ionic liquid (14.1 kJ m⁻³). In addition, the SMPs of the system were; strain (44%), shape fixation ratio (99%), and shape recovery (88%) as a result of the controlled crosslinking points. Interestingly, we coincidentally found that TBPC suppresses the photochromic activity of titania despite UV irradiation (250 W, 2 h), which helps to improve the degradation of titania hybrid film transparency. The use of TBPC in hybrid films is effective for designing materials with multifunctionality, including optical, mechanical, and shape memory properties.

Materials that exhibit the photo-induced magnetic-phase transition of titania are receiving significant attention because they can be easily switched between diamagnetism and paramagnetism by UV irradiation. However, it is difficult to store photo-induced titanium (Ti³⁺) in air because of its easy oxidation upon oxygen exposure. In this study, titania/polycarbonate hybrid films were prepared using linear 1,6-hexanediol (PHMCD), cyclic 1,4-cyclohexanedimethanol (PCHCD), or their copolymerized carbonate oligomers using the sol–gel method. The oxygen permeability of the hybrid film decreased as the ratio of the ring structure increased by a factor of approximately 32 from PHMCD with only the chain structure to PCHCD with only the ring structure. These hybrid films can generate Ti³⁺ under a UV irradiation of 250 W for 2 h, and the difference in oxygen permeability significantly affected the lifetime of the Ti³⁺ by a factor of up to 120. In addition, the tensile tests and IR measurements demonstrated that UV irradiation had little effect on the mechanical intensity and matrix chemical structure. Moreover, the magnetic susceptibility of Ti³⁺ present in PCHCD was confirmed to be 6.2 (10⁻³ emu/g(titania)) under an external magnetic field of 5 T induced using a superconducting quantum interference device.

Metal-carbon composites have recently gained attention as potential hydrogen storage materials. In the present investigation, carbon blacks (CBs) with 0.6 mass %, 4.9 mass %, and 9.3 mass % of Pd were prepared to investigate the cooperative effect together with Pd and CB for hydrogen storage. The hydrogen adsorption isotherms were measured at 77 K, 98 K, 123 K, 148 K, 173 K, 223 K, and 273 K under mild pressures below 1 MPa. The lower temperature gave the higher hydrogen content. Almost all the hydrogen contents of Pd-modified CBs exceeded the sum of the adsorption contents of CB and the occluded amounts of the assumed hydride, PdH_0.6. The highest hydrogen content was recorded for Pd 0.6 mass %-modified CB at 77 K. At temperatures above 77 K, CBs with the higher Pd contents adsorbed more hydrogen than Pd 0.6 mass %-modified CB, and they indicated an increase in the absolute values of adsorption enthalpy with the progress of adsorption. Pd was thought to be at first blocking deep potential sites, with accessibility to hydrogen acceptable sites gradually increasing as adsorption progressed.