Search Results (5)

Hydrogels are extensively utilized in biomedical fields because of their remarkable properties, including biocompatibility, high water content, flexibility, and elasticity. However, despite substantial progress in hydrogel research, creating a hydrogel adhesive that integrates high stretchability, fatigue resistance, and reversible adhesion continues to pose significant challenges. In this study, we aimed to address these challenges by preparing hydrogels using a combination of acrylic acid, acrylamide, carboxymethylcellulose methacrylate, thiol-functionalized polyhedral oligomeric silsesquioxane, and poly(ethylene glycol) dimethacrylate (PEGDM). By systematically varying the molecular weight of PEG, we were able to precisely adjust the mechanical and adhesive properties of the hydrogels. Our research revealed that a PEG molecular weight of 2000 (resulting in P1 hydrogel) provided a notable adhesive strength of 717.2 kPa on glass surfaces. This performance is particularly impressive given the challenges associated with achieving high adhesive strength while maintaining other desirable hydrogel properties. Beyond its strong adhesive capabilities, the P1 hydrogel also demonstrated exceptional stretchability, support, and fatigue resistance. These characteristics are crucial for applications where the adhesive needs to endure repeated stress and deformation without losing effectiveness. The successful development of P1 hydrogel underscores its potential as a multifunctional adhesive material with a broad range of applications. The ability to tailor the properties of hydrogels through molecular weight adjustments offers a promising approach to creating advanced adhesive solutions that meet the demanding requirements of modern biomedical and industrial applications. Full article

Recent advancements in geospatial technologies have significantly expanded the volume and diversity of geospatial data, unlocking new and innovative applications that require novel Geographic Information Systems (GIS). (Discrete) Global Grid Systems (DGGSs) have emerged as a promising solution to further enhance modern geospatial capabilities. Current DGGSs employ a simple, low-resolution polyhedral approximation of the Earth for efficient operations, but require a projection between the Earth’s surface and the polyhedral faces. Equal-area DGGSs are desirable for their low distortion, but they fall short of this promise due to the inefficiency of equal-area projections. On the other hand, efficiency-first DGGSs need to better address distortion. We introduce a novel mesh-based DGGS (MBD) which generalizes efficient operations over watertight triangular meshes with spherical topology. Unlike traditional approaches that rely on Platonic or Catalan solids, our mesh-based method leverages high-resolution spherical meshes to offer greater flexibility and accuracy. MBD allows high-resolution polyhedra (HRP) to be used as the base polyhedron of a DGGS, significantly reducing distortion. To address the operational challenges, we introduce a new hash encoding method and an efficient barycentric indexing method (BIM). MBD extends Atlas of Connectivity Maps to the BIM to provide efficient spatial and hierarchical traversal. We introduce several new base polyhedra with lower areal and angular distortion, and we experimentally validate their properties and demonstrate their efficiency. Our experimentation shows that we achieve constant-time operations for high-resolution MBD, and we recommend polyhedra to be used as the base polyhedron for low-distortion DGGSs, compact faces, and efficient operations. Full article

Honeycomb films pore-filled with metal (Au, Ag, and Cu) nanoparticles were successfully prepared by combining the breath figure method and an in situ reduction reaction. First, a polyhedral oligomeric silsesquioxane (POSS)-based star-shaped polymer solution containing metal salt was cast under humid conditions for the formation of honeycomb films pore-filled with metal salt through the breath figure method. The morphology of the honeycomb films was mainly affected by the polymer molecular structure and the metal salt. Interestingly, the promoting effect of the metal salt in the breath figure process was also observed. Then, honeycomb films pore-filled with metal nanoparticles were obtained by in situ reduction of the honeycomb films pore-filled with metal salt using NaBH₄. Notably, the metal nanoparticles can be selectively functionalized in the pores or on the surface of the honeycomb films by controlling the concentration of the NaBH₄. Metal-nanoparticle-functionalized honeycomb films can prospectively be used in catalysis, flexible electrodes, surface-enhanced Raman spectroscopy (SERS), and wettability patterned surfaces. Full article

Using organic coatings helps to protect PET (polyethylene terephthalates) surfaces, improve surface hardness, scratch resistance, and solvent resistance, prolong the service life of PET film, and to expand their scope of applications. There were some disadvantages, including poor flexibility and impact resistance in high-hardness coatings; organic coatings should also be modified to improve the toughness. Herein, a UV (ultraviolet curing) curable high-hardness organic coating used in PET surface protection was prepared and modified with inorganic nanoparticles, such as OVPOSS (octavinyl-polyhedral oligomeric silsesquioxane). The effects of the categories of nanoparticles on the coating performance were studied. UV-Vis spectra (ultraviolet visible light spectra), FT-IR (Fourier transform infrared spectrometer), TGA (thermogravimetric analysis), DMA (dynamic-mechanical), SEM (field emission scanning electron microscope), and AFM (atomic force microscope) were used to characterize the properties of the coatings. The results showed that the addition of eight-vinyl POSS to the organic coating significantly increased its glass transition temperature (T_g) from 100 to 120 °C, improved its storage modulus from 167.6 to 258.9 MPa, and raised its impact resistance and flexibility. The SEM and AFM images displayed that the eight-vinyl POSS particles were dispersed homogeneously in the coating, arranged in an ordered network, and had good compatibility with organic components. The film displayed excellent properties, including 4 H of the pencil hardness, 100 g cm of impact resistance, excellent flexibility, and 90% of light transmittance, with the addition of 0.3 wt % OVPOSS. TGA analysis revealed that the coating had good thermal stability, with 5% weight loss temperature up to 335 °C. Full article

We present three types of polyhedral surfaces, which are continuously flexible and have not only an initial pose, where all faces are coplanar, but pass during their self-motion through another pose with coplanar faces (“flat pose”). These surfaces are examples of so-called rigid origami, since we only admit exact flexions, i.e., each face remains rigid during the motion; only the dihedral angles vary. We analyze the geometry behind Miura-ori and address Kokotsakis’ example of a flexible tessellation with the particular case of a cyclic quadrangle. Finally, we recall Bricard’s octahedra of Type 3 and their relation to strophoids. Full article