Because the adhesives usually consist of the multicomponents containing the polymer, the knowledge such as not only the miscibility between components but also the structure and properties in the adhesion interface is very important. We measured the interfacial thickness and the concentration profile between different polymers by using an ellipsometry and some methods of microscopy, and considered these from the viewpoint of miscibility. And, in order to investigate the initial formation process of the interface, the behavior of interfacial region was measured by a high-speed ellipsometry,whose measuring-time-interval was very short. It was considered that high mobility and entropic elasticity of the interfacial molecules contributed to the formation of the interfacial region on the initial stage. Moreover, the adhesion strength was measured in non-reactive and reactive systems and the relation between interfacial structure and adhesion strength was discussed.
Adhesion between dissimilar materials is one of important issues in materials technologies. The bond formation between dissimilar materials should be effective to achieve the adhesion between the materials. Herein we conduct the direct adhesion of materials using non-covalent bond and covalent bond formation. We observed an external stimuli responsive adhesive system between cyclodextrin host-gels (CD gels) and guest molecules modified glass substrates (guest Sub). Using Suzuki-Miyaura cross-coupling reaction as covalent bond formation reaction, we observed direct adhesion between dissimilar materials (polymeric and inorganic materials). Glass substrate modified with iodoaryl group (I-Sub) selectively adhered to the hydrogel with an phenyl boronic acid (PB gel) using the cross-coupling reaction. The object (adhered PB gel and I-Sub) did not separate because the covalent bonds do not decompose and dissolve upon immersing into organic solvents. Cu-catalyzed azide-alkyne cycloaddition reaction and Sonogashira cross-coupling reaction can be applied to direct adhesion between gels and glass substrates. These results indicate that these reactions can be used for direct adhesion between dissimilar materials.
A method for debonding polyimide film and ultra-thin glass from glass substrate is proposed. The method is based on the surface activated bonding approach extended to a modified bonding process using Si nano-adhesion layer. The surfaces of both polyimide film and the glass substrate are activated by Si nano-adhesion layer deposited in vacuum and bonded in situ at room temperature whereas only the ultra-thin glass surface is treated with Si nano-adhesion layer, and bonded in vacuum to glass substrate after exposure to N2 gas. Even after a thermal treatment such as TFT process over 400 to 500°C, they can be debonded by mechanical peeling at room temperature.
This research demonstrates a newly developed technique to fabricate multilevel interconnections with differential adhesion strengths between metal and silicon-oxide (SiO2) thin films. In the field of micro electromechanical systems (MEMS), the various kinds of metals have been applied as functional materials, i.e. low resistance, high-temperature endurance, catalyst and so on. However, several kinds of metals are not applied on the SiO2 thin film, since an adhesion strength between metal and SiO2 thin films is not enough. Thus, the adhesion strengths (delamination energies) were estimated with a molecular dynamics simulation, and the metals of the lower wiring and the contact area were experimentally determined to easily fabricate the multilevel interconnections. Consequently, the Cr, Ti and Ni thin films can be applied as the adhesion layer on the lower wiring, and the Au and Cu thin films can be applied as the release layer on the contact area.
Hydrogels have attracted much attention for their biocompatibility and tunable properties for use in tissue engineering and regenerative medicine. Cellular adhesion and organization can be controlled by the microstructure of the scaffold. Here, we describe a new cellulose-based bundled hydrogel fiber fabricated by a dynamic microfluidic gelation system that utilizes a phase-separated polymer blend solution and a co-flow microfluidic device. In addition, multi-walled carbon nanotubes were embedded to enhance the mechanical and electrical properties of the gel fibers. Using normal human dermal fibroblasts, we demonstrated the bundled gel fibers facilitate cellular attachment and orientation. These results demonstrate that the bundled gel fiber may be useful in tissue engineering applications as a cell scaffold with tunable properties.
In this Technical Note, we describe the use of adhesives for vacuum seal and sample fixation. Some of epoxy resin with inorganic filler can be used to assemble small vacuum chambers and water/current feedthrough for high vacuum, if enough caution is provided. An alloy sheet made of metal foils and boron oxide glass can be used to fix a sample to a holder.