Evaluation of internal network structure of transparent shape memory gels and application of T-SMG to develop gel devices

Abstract

Gels, soft and wet materials, have unique properties such as biocompatibility, low friction, and material permeability which are hardly found in hard and dry materials. In recent years, gels are expected to industrial applications, because the various high-strength gels, functional gels, and 3D gel printer that enabled free form fabrication of gels have been developed. Our research group succeeded in developing transparent gels with shape memory properties (T-SMG). In this study, we aimed at free form fabrication of T-SMG with to apply T-SMG’s new medical materials, optical devices, and robot joints and so on. We also examined the internal network structure of T-SMG, since it is very important to know the internal network structure of the gels in order to improve the gels. We study the internal network structure of T-SMG through the dynamic light scattering, uniaxial tensile test, and swelling test. As a result, we found that T-SMG is a unique material that changes the internal structure considerably depending on the presence or absence of crystal components. The state of chemical components changes physical properties such as mechanical properties and swelling behavior, without changing the synthesis ratio. In addition, even though the crystals were melted, it showed a higher Young ‘s modulus than the amorphous gels, it was suggested that the crystal components contributes to the Young’ s modulus even though it melted. We tried free form fabrication of T-SMG using 3D printing system. As T-SMG become cloudy at the time of printing, the modeling accuracy become worse. However, by mixing UV absorbers, it was possible to improve the accuracy and suppression of clouding of gels. We successfully made the fine and complicated shaping of T-SMG which was difficult in the past processes. Based on this technology, we hope that T-SMG will be applied in various fields.