We present an approach which makes it possible to directly determine the bending modulus of single elongated block copolymer micelles. This is done by forming arrays of suspended micelles onto microfabricated substrates and by performing three-point bending flexural tests, using an atomic force microscope, on their suspended portions. By coupling the direct atomic force microscopy measurements with differential scanning calorimetry data, we show that the presence of a crystalline corona strongly increases the modulus of the copolymer elongated micelles. This large increase suggests that crystallites in the corona are larger and more uniformly oriented due to confinement effects. Our findings together with this hypothesis open new interesting avenues for the preparation of core-templated polymer fibres with enhanced mechanical properties.
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http://dx.doi.org/10.1039/c6sm00983b | DOI Listing |
J Dent
January 2025
University of Saskatchewan, College of Dentistry. 107 Wiggins Rd, Saskatoon, SK, Canada. S7N 5E5. Electronic address:
Bulk-fill, monochromatic, and ORMOCER composites were introduced in restorative dentistry with the aim of reducing clinical time and/or alleviating contraction stresses at the interface between the tooth and restoration. While the conversion and immediate properties of these materials are comparable to conventional composites, studies evaluating their long-term properties and the structure of the polymer matrix are lacking. The objective of this study was to evaluate the degree of conversion and, indirectly, the crosslink density of conventional, bulk-fill, monochromatic, and ORMOCER resin composites.
View Article and Find Full Text PDFJ Mech Behav Biomed Mater
January 2025
Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA; Center for Multiscale and Translational Mechanobiology, Boston University, Boston, MA 02215, USA; Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA.
Despite the broad agreement that bone stiffness is heavily dependent on the underlying bone density, there is no consensus on a unified relationship that applies to both cancellous and cortical compartments. Bone from the two compartments is generally assessed separately, and few mechanical test data are available for samples from the transitional regions between them. In this study, we present a data-driven framework integrating experimental testing and numerical modeling of the human lumbar vertebra through an energy balance criterion, to develop a unified density-modulus relationship across the entire vertebral body, without the necessity of differentiation between trabecular and cortical regions.
View Article and Find Full Text PDFBiomech Model Mechanobiol
January 2025
Department of Mechanical and Aerospace Engineering, University of Houston, Houston, TX, 77204, USA.
The Gaussian modulus is a crucial property that influences topological transformations in lipid membranes. However, unlike the bending modulus, estimating the Gaussian modulus has been particularly challenging due to the constraints imposed by the Gauss-Bonnet theorem. Despite this, various theoretical, computational, and experimental approaches have been developed to estimate the Gaussian modulus, though they are often complex, and analytical estimates remain rare.
View Article and Find Full Text PDFLangmuir
January 2025
State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, China.
Palm leaf manuscripts, crafted from specially treated palm leaves, are invaluable historical documents. However, they degrade and tend to become brittle over time. To date, plant essential oils and glycerin are the used materials to improve the flexibility of palm leaf manuscripts, but the effective duration of these materials is short due to their volatility.
View Article and Find Full Text PDFMaterials (Basel)
January 2025
Department of Integrated Design and Tribology Systems, Faculty of Mechanics and Technology, Rzeszów University of Technology, ul. Kwiatkowskiego 4, 37-450 Stalowa Wola, Poland.
In addition to the traditional uses of plywood, such as furniture and construction, it is also widely used in areas that benefit from its special combination of strength and lightness, particularly as a construction material for the production of finishing elements of campervans and yachts. In light of the current need to reduce emissions of climate-damaging gases such as CO, the use of lightweight construction materials is very important. In recent years, hybrid structures made of carbon fibre-reinforced plastics (CFRPs) and metals have attracted much attention in many industries.
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