scholarly journals Strain- and field-induced anisotropy in hybrid elastomers with elongated filler nanoparticles

Soft Matter ◽  
2021 ◽  
Author(s):  
Julian Seifert ◽  
Damian Günzing ◽  
Samira Webers ◽  
Martin Dulle ◽  
Margarita Kruteva ◽  
...  

The implementation of anisotropy to functional materials is a key step towards future smart materials. In this work, we evaluate the influence of preorientation and sample architecture on the strain-induced...

2020 ◽  
Vol 05 ◽  
Author(s):  
Silas Santos ◽  
Orlando Rodrigues ◽  
Letícia Campos

Background: Innovation mission in materials science requires new approaches to form functional materials, wherein the concept of its formation begins in nano/micro scale. Rare earth oxides with general form (RE2O3; RE from La to Lu, including Sc and Y) exhibit particular proprieties, being used in a vast field of applications with high technological content since agriculture to astronomy. Despite of their applicability, there is a lack of studies on surface chemistry of rare earth oxides. Zeta potential determination provides key parameters to form smart materials by controlling interparticle forces, as well as their evolution during processing. This paper reports a study on zeta potential with emphasis for rare earth oxide nanoparticles. A brief overview on rare earths, as well as zeta potential, including sample preparation, measurement parameters, and the most common mistakes during this evaluation are reported. Methods: A brief overview on rare earths, including zeta potential, and interparticle forces are presented. A practical study on zeta potential of rare earth oxides - RE2O3 (RE as Y, Dy, Tm, Eu, and Ce) in aqueous media is reported. Moreover, sample preparation, measurement parameters, and common mistakes during this evaluation are discussed. Results: Potential zeta values depend on particle characteristics such as size, shape, density, and surface area. Besides, preparation of samples which involves electrolyte concentration and time for homogenization of suspensions are extremely valuable to get suitable results. Conclusion: Zeta potential evaluation provides key parameters to produce smart materials seeing that interparticle forces can be controlled. Even though zeta potential characterization is mature, investigations on rare earth oxides are very scarce. Therefore, this innovative paper is a valuable contribution on this field.


2015 ◽  
Vol 36 (1) ◽  
pp. 19-30
Author(s):  
Justyna Barska ◽  
Sylwester Kłysz

AbstractThe article presents a wide range of applications of functional materials and a scale of their current industrial production. These are the materials which have specific characteristics, thanks to which they became virtually indispensable in certain constructional solutions. Their basic characteristics, properties, methods of production and use as smart materials were described.


2008 ◽  
Vol 47-50 ◽  
pp. 511-514 ◽  
Author(s):  
Adrian Bejan ◽  
Sylvie Lorente

Here we draw attention to the development of smart materials with embedded vasculatures that provide multiple functionality: volumetric cooling, self-healing, mechanical strength, etc. Vascularization is achieved by using tree-shaped (dendritic) and grid-shaped flow architectures. As length scales become smaller, dendritic vascularization provides dramatically superior volumetric bathing and transport properties than the use of bundles of parallel microchannels. Embedded grids of channels provide substantially better volumetric bathing when the channels have multiple diameters that are selected optimally and put in the right places. Two novel dendritic architectures are proposed: trees matched canopy to canopy, and trees that alternate with upside down trees. Both have optimized length scales and layouts. Flow architectures are derived from principle, in accordance with constructal theory, not by mimicking nature.


Author(s):  
Jinsheng Fan ◽  
David Gonzalez ◽  
Jose Garcia ◽  
Brittany Newell ◽  
Robert A. Nawrocki

Abstract Mechanical flexibility, faster processing, lower fabrication cost and biocompatibility enable poly (vinylidene fluoride) (PVdF) to have a wide range of applications. This work investigated the use of a piezoelectric polymeric material, PVdF, in combination with 3D printing, to explore new strategies for the fabrication of smart materials with embedded functions, namely sensing. The motivation behind this research was to design and fabricate PVdF thin films that will be used to build pressure sensors with applications in active intelligent structures. In this work, 3D printed PVdF thin films with thickness values in the range of 250 to 350 μm were poled under high direct current electrical fields, which were varied from 0.4 to 12 MV/m and temperatures from 80 to 140 °C. Copper electrodes were applied, forming a standard capacitor layered structure, to facilitate poling and to collect piezoelectric output voltage. The poling process enabled the piezoelectric crystalline phase transition of printed PVdF films to transfer from the non-active a α-phase to the piezoelectric active β-phase and rearranged the dipole alignments of the β-phase. The efficiency of poling was evaluated through the piezoelectric constant calculated from measured calibration curves. These calibration curves demonstrated the PVdF sensing device have a positive linear correlation between mechanical input and voltage output. We found that a peak value in piezoelectric constant correlated with poling voltages and temperatures. The highest piezoelectric constant achieved through contact poling was 32.29 pC/N poled at 750 V and 120 °C, and temperature was deemed the most important factors to influence piezoelectric constant. We believe that the present work demonstrates a path towards fully 3D printed smart, functional materials.


Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 630 ◽  
Author(s):  
José María Cuevas ◽  
Rubén Seoane-Rivero ◽  
Rodrigo Navarro ◽  
Ángel Marcos-Fernández

Polyurethanes are of undoubted interest for the scientific community and the industry. Their outstanding versatility from tailor-made structures turns them into major polymers for use in a wide range of different applications. As with other polymers, new, emerging molecules and monomers with specific attributes can provide new functions and capabilities to polyurethanes. Natural and synthetic coumarin and its derivatives are characterised by interesting biological, photophysical and photochemical properties. Then, the polyurethanes can exploit those features of many coumarins which are present in their composition to achieve new functions and performances. This article reviews the developments in the proper use of the special properties of coumarins in polyurethanes to produce functional and smart materials that can be suitable for new specific applications.


Author(s):  
Inseok Chae ◽  
Amira Meddeb ◽  
Zoubeida Ounaies ◽  
Seong H. Kim

Liquid crystalline (LC) behaviors of cellulose nanocrystal (CNC), derived from wood, cotton or other cellulose-based biopolymers, have been actively investigated due to their unique optical properties and their superb mechanical properties, which open up potential applications in bioelectronics and biomedical engineering. In particular, many attempts have been made to control phase and orientation of LC-CNCs because they are critical factors deciding optical and mechanical properties, and electromechanical performances. Through the applications of mechanical force, electric field and magnetic field, some degree of success has been achieved; however, realizing homogeneous arrangements of CNCs that can be exploited at the macroscale is still elusive, owing to a variety of intermolecular interactions. The characterizations of the LC phase and orientation of CNCs are also challenging due to their complex biological structures. In this report, we introduce approaches to control the phase and orientation of LC-CNCs through the self-assembly, mechanical force and electric field. The liquid crystalline behaviors of CNCs in polar solvents and at the air/water interface are discussed. Translational and rotational behaviors of CNCs under DC electric field are also investigated as a function of their surface charge and dipole moment. In addition, we introduce a nonlinear optical process, namely, sum frequency generation (SFG) spectroscopy, for the structural characterization of LC-CNCs. Using SFG, we can analyze not only crystal phase and structure, but also polar ordering of CNCs which plays a key role in determining their electromechanical performances. Development of cellulose-based smart materials will expand the spectrum of available functional materials that are lightweight, flexible, mechanically tough, and thermally stable at moderately high temperatures (up to 300°C).


2009 ◽  
Vol 6 (4) ◽  
pp. 219-227 ◽  
Author(s):  
T. Grund ◽  
C. Megnin ◽  
J. Barth ◽  
M. Kohl

Polymer based microvalves offer outstanding properties for biomedical and life science applications. They can be produced cost efficiently by batch fabrication methods. Further, by adapting the polymer material, custom-tailored properties of the valve are possible. For mechanically active microvalves, actuation with smart materials like shape memory alloys is highly attractive due to their high work output per volume and favorable scaling behavior. For the integration of such smart materials, fabrication process incompatibilities between the actuator material and the polymer target system need to be avoided. This can be achieved by novel transfer bonding technologies being optimized for batch fabrication. These technologies are demonstrated for polymer microvalves actuated by a shape memory alloy but they can also be applied to other functional materials and structures.


2005 ◽  
Vol 888 ◽  
Author(s):  
K. Jai Ganesh ◽  
Arunya Suresh

ABSTRACTShape Memory Alloys (SMAs) are versatile functional materials with an I.Q of their own. This class of SMART Materials exhibit unique properties like superelasticity and shape memory effect (SME) which have made them suitable for potential applications. Although Ni-Ti SMAs have attracted attention ever since their inception in 1962, Cu based SMAs due to their ease in fabrication, cost effectiveness and high temperature properties are gaining immense popularity. This research aimed at the fabrication of Cu-14 Al-3.5 Ni (wt %) Shape Memory Alloy by a simple cost effective route and its characterization to correlate its structure and properties. The alloy of desired composition was melted in an Electric Resistance Furnace at 1473 K and cast in a metallic mould. Homogenization was carried out at 1123 K for twenty four hours followed by analysis of chemical composition by Optical Emission Spectroscopy. Transformation temperatures of the alloy were determined using Differential Scanning Calorimetry. Heat treatment operations were carried out at 1273 K for one hour followed by quenching in different media. Optical and SEM micrographs were taken at various magnifications and the formation of self accommodating martensite was observed which was further confirmed by X-Ray Diffraction technique. Further improvements in the mechanical properties of the alloy by quaternary additions of Mn and Ti have been cited. Finally, SME was observed in a rolled strip of the alloy, thus concreting the obtained results.


Nanophotonics ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 1139-1160 ◽  
Author(s):  
Hoon Yeub Jeong ◽  
Eunsongyi Lee ◽  
Soo-Chan An ◽  
Yeonsoo Lim ◽  
Young Chul Jun

AbstractThree-dimensional (3D) printing is a new paradigm in customized manufacturing and allows the fabrication of complex optical components and metaphotonic structures that are difficult to realize via traditional methods. Conventional lithography techniques are usually limited to planar patterning, but 3D printing can allow the fabrication and integration of complex shapes or multiple parts along the out-of-plane direction. Additionally, 3D printing can allow printing on curved surfaces. Four-dimensional (4D) printing adds active, responsive functions to 3D-printed structures and provides new avenues for active, reconfigurable optical and microwave structures. This review introduces recent developments in 3D and 4D printing, with emphasis on topics that are interesting for the nanophotonics and metaphotonics communities. In this article, we have first discussed functional materials for 3D and 4D printing. Then, we have presented the various designs and applications of 3D and 4D printing in the optical, terahertz, and microwave domains. 3D printing can be ideal for customized, nonconventional optical components and complex metaphotonic structures. Furthermore, with various printable smart materials, 4D printing might provide a unique platform for active and reconfigurable structures. Therefore, 3D and 4D printing can introduce unprecedented opportunities in optics and metaphotonics and may have applications in freeform optics, integrated optical and optoelectronic devices, displays, optical sensors, antennas, active and tunable photonic devices, and biomedicine. Abundant new opportunities exist for exploration.


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