Polyurethane composite foams were prepared by adding three different types of silica materials as a filler to improve the mechanical and thermal insulation properties. The first type of filler consists of silica aerogels with high-volume pores, with the expectation of improving the thermal insulation of PU foams because silica aerogel itself has superior thermal insulation properties. Silica nanoparticle is used for the second type that has a size very similar to the pore size of silica aerogels for comparison. The last type to produce polyurethane composite foam uses a sol–gel reaction to produce polysiloxane that reacts with polyols during the urethane reaction and forming process. In particular, in the case of silica aerogels and nanoparticles, their surfaces are modified with APTES and then polymeric methylene diphenylene diisocyanate (PMDI) to increase the interaction between the polymer matrix and inorganic fillers. The polyurethane foam structure was successfully produced in all cases of composite foams. As expected, the mechanical properties and the thermal insulation effect were enhanced by the addition of silica fillers, but found to be closely related to the cell structure of polyurethane foams. The addition of small amounts of inorganic fillers improves the mechanical and thermal properties, but the higher the amount of filler, the worse they are due to the agglomeration of fillers on the cell walls. The dispersion of added inorganic fillers within the foam cells should be controlled effectively. Surface-modified silica fillers exhibit better enhancement of mechanical and thermal insulation properties.

The surface nanotopography of polymer scaffolds is one of the most critical factors affecting cell phenotype and function in tissue engineering applications. We hypothesized that controlling the surface structure of polymer matrices on the nanometer size scale could be critical in the regulation of preosteoblast phenotypes. Nano-structured polymer surfaces on the sub-100 nanometer scale were produced via the self-assembly of polystyrene-b-poly(ethylene oxide)/dodecylbenzenesulfonic acid complex systems, and their structures were controlled by varying the composition and molecular weight of the copolymers and/or the surfactant concentration. Changes in PS domain sizes under 100 nm, which was considered the cell adhesion domain, strongly influenced the adhesion and proliferation of pre-osteoblasts cultured on the nano-patterned surfaces. The growth rate of the cells decreased as the PS domain size increased when the center-to-center distance between the domains was kept constant. In addition, osteoblastic differentiation was enhanced when cells were cultured on the surface containing larger adhesion domains. This approach to controlling the nano-structure of polymer surfaces may be useful in the design and tailoring of polymer scaffolds in tissue engineering applications.

In recent years, natural disasters have been increasing worldwide due to rapid climate change, and the damage to ground structures is increasing due to the destruction of the ground. Damage to the ground structure can be reduced or eliminated by using LCP woven geotextiles as ground reinforcement. Therefore, in this study, the tensile properties, reduction factor affecting long-term performance, creep behavior, and fatigue properties of LCP woven geotextile were tested and analyzed. As a result, in the case of tensile properties, the maximum tensile strength of the LCP woven geotextile was 192.94 kN/m² in the MD direction, and it was generally constructed so that the load was transmitted. The total reduction factor is 1.86, which could be applied within 53.8% of the design strength when applied to the field. In addition, it was considered that the effect of the reduction factor for creep deformation on the long-term performance was dominant. Through the analysis of the creep behavior and fatigue characteristics, considering that the creep limit strain was 10%, if an earthquake occurred after 50 years of construction, it can be predicted that up to 90% of UTS would exhibit seismic performance. When LCP woven geotextile was applied as reinforcement, if the cyclic load due to fatigue failure was less than 478,000 times per year, it was considered that there was little possibility of the collapse of the ground structure.