scholarly journals A Highly Versatile Polymer Network Based on Liquid Crystalline Dendrimers

2021 ◽  
Vol 22 (11) ◽  
pp. 5740
Author(s):  
Ramón Cervera-Procas ◽  
José-Luis Serrano ◽  
Ana Omenat
Keyword(s):  
Smart Materials ◽  
Liquid Crystalline ◽  
Organic Dyes ◽  
Polymer Network ◽  
Viscoelastic Behavior ◽  
Diverse Range ◽  
Polymeric Systems ◽  
System A ◽  
Porous Microstructure ◽  
Solvent Molecules

Highly functional macromolecules with a well-defined architecture are the key to designing efficient and smart materials, and these polymeric systems can be tailored for specific applications in a diverse range of fields. Herein, the formation of a new liquid crystalline polymeric network based on the crosslinking of dendrimeric entities by the CuI-catalyzed variant of the Huisgen 1,3-dipolar cycloaddition of azides and alkynes to afford 1,2,3-triazoles is reported. The polymeric material obtained in this way is easy to process and exhibits a variety of properties, which include mesomorphism, viscoelastic behavior, and thermal contraction. The porous microstructure of the polymer network determines its capability to absorb solvent molecules and to encapsulate small molecules, like organic dyes, which can be released easily afterwards. Moreover, all these properties may be easily tuned by modifying the chemical structure of the constituent dendrimers, which makes this system a very interesting one for a number of applications.

Uv Curable Liquid Crystals and Their Application

1996 ◽  
Vol 425 ◽  
Author(s):  
H. Takatsu ◽  
H. Hasebe
Keyword(s):  
Liquid Crystals ◽  
Light Scattering ◽  
Liquid Crystalline ◽  
Room Temperature ◽  
Polymer Network ◽  
Driving Voltage ◽  
Uv Curable ◽  
Good Thermal Stability ◽  
Photo Polymerization ◽  
Smectic A

AbstractSome classes of liquid crystalline monoacrylates having no methylene spacers in a side chain have been prepared. The liquid crystalline monoacrylates have effects to reduce the driving voltage and the hysteresis for a light scattering display of Polymer Network liquid crystals prepared by photo-polymerization-induced phase separation.By photo-polymerization of a chiral monoacrylate monomer in a nematic liquid crystalline host including a black dichroic dye, a polarizer free reflective Spiral Polymer Aligned Nematic (SPAN) Guest Host (GH) LCD exhibiting a low driving voltage has been fabricated. The effect of the spiral polymers made of some kinds of chiral monoacrylates for a Super Twisted Nematic (STN) LCD using SPAN liquid crystals is discussed.UV-curable liquid crystals showing nematic phases at room temperature have been developed. By in situ photo-polymerization, the UV-curable liquid crystals can be utilized for the retardation film with high quality and good thermal stability. The fabrication of various kinds of retardation film using the UV-curable liquid crystals is discussed.UV-curable liquid crystals having isotropic-nematic-smectic A phase sequence have been developed and the photo-polymerization at the state of their uniaxially oriented smectic A phases at room temperature is discussed. The polymerized film is optically uniaxial and transparent without light scattering.

Use of Self-Induced Zernike Filters Based on Saturation Effect in Gas Flow Schlieren Diagnostics

2014 ◽  
Vol 9 (1) ◽  
pp. 15-28
Author(s):  
Alexey Pavlov ◽  
Aleksandr Pavlov ◽  
Maxim Golubev
Keyword(s):  
Focal Plane ◽  
Quantitative Data ◽  
Gas Flow ◽  
Organic Dyes ◽  
Thin Layers ◽  
Saturable Absorption ◽  
Use Of Self ◽  
Absorption Effect ◽  
System A ◽  
Schlieren System

New self-induced Zernike filters (adaptive visualizing transparencies) based on the saturable absorption effect are suggested. The transparencies are thin layers made of translucent absorbing substance, and are placed in the focal plane of the receiving lens of a schlieren system. A possibility to create the transparencies having low response time (10−4 –10−5 s), which significantly reduces liability of the system to vibrations, is demonstrated. Obtainable images are equal to infinitefringe interference patterns allow getting a quantitative data. Examples of application of the organic dyes transparencies in aerophysic experiments are presented

Coupling of liquid crystalline and polymer network properties in LC-elastomers

1996 ◽  
Vol 21 (4) ◽  
pp. 589-596 ◽  
Author(s):  
M. Brehmer ◽  
R. Zentel ◽  
F. Gießbtelmann ◽  
R. Germer ◽  
P. Zugenmaier
Keyword(s):  
Liquid Crystalline ◽  
Polymer Network ◽  
Network Properties

Continuous Structures With Viscoelastic Supports: Tuning of Material Parameters and Support Location

2015 ◽  
Author(s):  
Kumar Vikram Singh ◽  
Danielle Oliver ◽  
Xiaoxuan Ling
Keyword(s):  
Smart Materials ◽  
Loss Factor ◽  
Eigenvalue Problems ◽  
Equations Of Motion ◽  
Viscoelastic Behavior ◽  
Vibration Response ◽  
Tuning Parameters ◽  
Wide Range ◽  
Analytical Response ◽  
Optimal Material

Polymeric smart materials exhibit viscoelastic behavior and their dynamic characteristics are dependent on both frequency and temperature. This allows the tuning of material properties (stiffness and loss factor) to manipulate the vibration behavior for a wide range of engineering applications. In this research, the effects of viscoelastic supports on the vibration of continuous structures such as axially vibrating rods and transversely vibrating beams are investigated. The governing equations of motion for harmonically excited rods with end supports, and the free vibration of beams with intermediate viscoelastic support are developed. The analytical response equation for a harmonically excited rod with viscoelastic ends is obtained. The resulting frequency response equations are then used to design the modification of the stiffness and loss factor of the viscoelastic materials in order to achieve the desired vibration response of the rod. By solving the resulting transcendental eigenvalue problems, the natural frequencies and damping ratios as a function of viscoelastic support parameters are computed for beams. The performance of structures with viscoelastic support is demonstrated with various numerical examples. The formulation and results can be utilized for estimating the optimal material tuning parameters as well as support locations for controlling and manipulating the vibration response of the structures.

Microstructural characterization and effective viscoelastic behavior of magnetorheological elastomers with varying acetone contents

2016 ◽  
Vol 26 (1) ◽  
pp. 104-118 ◽  
Author(s):  
Robbie Damiani ◽  
LZ Sun
Keyword(s):  
Mechanical Properties ◽  
Smart Materials ◽  
Three Dimensional ◽  
Viscoelastic Behavior ◽  
Microstructural Characterization ◽  
Iron Particle ◽  
Magnetorheological Elastomers ◽  
Micro Particles ◽  
Particle Alignment ◽  
Magnetorheological Effect

Magnetorheological elastomers (MREs), a class of polymer-based composites with dispersed ferromagnetic micro-particles, fall in the class of smart materials, because their macroscopic or effective rheological properties can be continuously, rapidly, and reversibly changed with the application of a magnetic field. Conventional magnetorheological elastomers exhibit poor mechanical properties and magnetorheological effect as a result of their matrix materials and the particle-matrix interfaces. Here, we investigate the effect of acetone contents on the magnetorheological elastomer microstructure at the interfacial regions using the scanning electron microscope and the three-dimensional nano-CT imaging, as well as determining the overall or effective mechanical properties of magnetorheological elastomers. It is shown that acetone increases both the overall storage modulus and loss factor along with the magnetorheological effect due to acetone’s reaction on the interface as well as its effect on iron particle alignment.

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