scholarly journals Water Triggered Shape Memory Materials

2013 ◽  
Vol 3 (1) ◽  
pp. 49-50 ◽  
Author(s):  
Guoguang Niu
Keyword(s):  
Shape Memory ◽  
Shape Recovery ◽  
Shape Memory Polymers ◽  
Electrical Current ◽  
Light Illumination ◽  
Poly Ethylene Glycol ◽  
Thermally Induced ◽  
Permanent Shape ◽  
Poly Ethylene ◽  
Novel Strategy

The term "shape memory effect" refers to the ability of a material to be deformed and fixed into a temporary shape, and to recover its original, permanent shape upon an external stimulus (1). Shape memory polymers have attracted much interest because of their unique properties, and applied tremendously in medical area, such as biodegradable sutures, actuators, catheters and smart stents (2, 3). Shape memory usually is a thermally induced process, although it can be activated by light illumination, electrical current, magnetic, or electromagnetic field (4-6). During the process, the materials are heated directly or indirectly above their glass transition temperature (Tg) or the melting temperature (Tm) in order to recover the original shape. Non-thermally induced shape memory polymers eliminate the temperature constrains and enable the manipulation of the shape recovered under ambient temperature (7, 8). Herein, we report a novel strategy of water induced shape memory, in which the formation and dissolution of poly(ethylene glycol) (PEG) crystal is utilized for the fixation and recovery of temporary deformation of hydrophilic polymer. This water-induced shape recovery is less sensitive to temperature, of which 95% deformation is fixed in circumstance and over 75% recovery is reached even at 0 oC.

scholarly journals A Large-Deformation Theory for Thermally-Actuated Shape-Memory Polymers and its Application

2010 ◽  
Author(s):  
Shawn A. Chester ◽  
Vikas Srivastava ◽  
Claudio V. Di Leo ◽  
Lallit Anand
Keyword(s):  
Glass Transition ◽  
Shape Memory ◽  
Deformation Theory ◽  
Shape Recovery ◽  
Large Deformations ◽  
Shape Memory Polymers ◽  
The Body ◽  
Thermally Induced ◽  
Thermally Actuated ◽  
Common Shape

The most common shape-memory polymers are those in which the shape-recovery is thermally-induced. A body made from such a material may be subjected to large deformations at an elevated temperature above its glass transition temperature &Vthgr;g. Cooling the deformed body to a temperature below &Vthgr;g under active kinematical constraints fixes the deformed shape of the body. The original shape of the body may be recovered if the material is heated back to a temperature above &Vthgr;g without the kinematical constraints. This phenomenon is known as the shape-memory effect. If the shape recovery is partially constrained, the material exerts a recovery force and the phenomenon is known as constrained-recovery.

Body temperature-responsive two-way and moisture-responsive one-way shape memory behaviors of poly(ethylene glycol)-based networks

2017 ◽  
Vol 8 (25) ◽  
pp. 3833-3840 ◽  
Author(s):  
Guang Yang ◽  
Xueyang Liu ◽  
Alfred Iing Yoong Tok ◽  
Vitali Lipik
Keyword(s):  
Free Radical ◽  
Ethylene Glycol ◽  
Shape Memory ◽  
Shape Memory Polymer ◽  
Polymer Networks ◽  
Poly Ethylene Glycol ◽  
Thermally Induced ◽  
Temperature Responsive ◽  
Shape Memory Effects ◽  
Poly Ethylene

In this work, crosslinked shape-memory polymer networks were prepared by thermally induced free-radical polymerizations of methacrylate-terminated poly(ethylene glycol) (PEG) and n-butyl acrylate (BA), which integrate thermal-responsive two-way and moisture-responsive one-way shape memory effects (SME).

Shape Memory Polymers Based on Polyhedral Oligomeric Silsesquioxane Grafted with Poly(ethylene glycol)s

Polymer Korea ◽  
2019 ◽  
Vol 43 (1) ◽  
pp. 106-112
Author(s):  
Haneum Park ◽  
Jiwon Lee ◽  
Jeongwan Chae ◽  
Jeong-Seon Sang ◽  
Kyung Wha Oh ◽  
...  
Keyword(s):  
Ethylene Glycol ◽  
Shape Memory ◽  
Polyhedral Oligomeric Silsesquioxane ◽  
Shape Memory Polymers ◽  
Poly Ethylene Glycol ◽  
Poly Ethylene ◽  
Oligomeric Silsesquioxane

Modeling Circular Shear in Shape Memory Polymers With Triple Shape Effect Subjected to Crystallization Under Constant Shear

2015 ◽  
Author(s):  
Swapnil Moon ◽  
I. Joga Rao ◽  
Fangda Cui
Keyword(s):  
Shape Memory ◽  
Smart Materials ◽  
First Generation ◽  
Shape Change ◽  
Shape Memory Polymers ◽  
Shape Effect ◽  
Crystalline Phases ◽  
Thermally Induced ◽  
Multiple Natural Configurations ◽  
Permanent Shape

The capacity of a material to sense its environment and to change its shape on demand in a predefined way has tremendous technological significance for a wide variety of application areas. Shape memory polymers (SMPs) belong to this category of smart materials as they have the ability to undergo a shape change in a predetermined manner under the influence of an external stimulus. SMPs can recover their permanent shape after undergoing large deformation to a temporary shape on exposure to external triggers such as light, PH values and heat. Thermally induced SMPs are first generation SMPs and have been widely recognized. Crystallizable SMPs are a class of thermally induced SMPs whose temporary shape is due to formation of crystalline phases, and they will revert back to their permanent shape when the crystallization phase is melted through heating. Traditional crystallizable SMPs can only perform dual-shape memory cycles and this limits applications of crystallizable SMPs. Recently SMPs with triple shape effect have been reported that can switch from a second temporary shape to the first temporary shape and from there to the permanent shape under stimulation by heat. Our research focuses on modeling the mechanical behavior of these SMPs with triple-shape effect. The framework used in developing the model is built upon the theory of multiple natural configurations [3]. In order to model the mechanics associated with these polymers different stages of the shape fixation and recovery cycle and different phases of the material during this cycle need to be characterized. This includes developing a model for the amorphous phase and the subsequent semi-crystalline phases with different stress free states and melting of these phases. The model subsequently has been used to simulate results for a typical deformation cycle involving circular shear.

Electro-thermo-mechanical modeling of shape memory polymers filled with nano-carbon powder

2021 ◽  
pp. 1045389X2110643
Author(s):  
Jianping Gu ◽  
Shenglin Zhao ◽  
Hao Duan ◽  
Mengqi Wan ◽  
Huiyu Sun
Keyword(s):  
Shape Memory ◽  
Filler Content ◽  
Shape Memory Polymer ◽  
Shape Memory Polymers ◽  
Electrical Current ◽  
Carbon Powder ◽  
Driving Mechanism ◽  
Recovery Ratio ◽  
Thermally Induced ◽  
Nano Carbon

Generally, adding the electroconductive fillers into the polymer matrix is a popular approach to endow the shape memory polymers (SMPs) with electroconductivity. Therefore, the shape memory effects (SMEs) of thermally induced SMPs can also be triggered by the electrical current. In essence, both the thermally activated and electrically activated SMEs share the same driving mechanism without considering the effect of heat conduction. In the paper, the constitutive model for the thermally induced SMPs filled with nano-carbon powder is briefly introduced. Then, a modified model is developed to characterize the effects of filler, deformation, and moisture on the electrical conductivity for the first time. After developing the correlation of electric field with Joule heat, the simulation is executed to display the free recovery of the shape memory polymer composites (SMPCs) with different filler content. It is found that the recovery ratio decreases with the increase of carbon powders for the SMPCs with filler content above the percolation threshold. Besides, a good recovery ratio can also be achieved through the application of a lower voltage.

scholarly journals Thermally-Induced Shape-Memory Behavior of Degradable Gelatin-Based Networks

2021 ◽  
Vol 22 (11) ◽  
pp. 5892
Author(s):  
Axel T. Neffe ◽  
Candy Löwenberg ◽  
Konstanze K. Julich-Gruner ◽  
Marc Behl ◽  
Andreas Lendlein
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Shape Recovery ◽  
Polymer Networks ◽  
Water Soluble ◽  
Compression Tests ◽  
Thermally Induced ◽  
Thermomechanical Process ◽  
Triple Helices

Shape-memory hydrogels (SMH) are multifunctional, actively-moving polymers of interest in biomedicine. In loosely crosslinked polymer networks, gelatin chains may form triple helices, which can act as temporary net points in SMH, depending on the presence of salts. Here, we show programming and initiation of the shape-memory effect of such networks based on a thermomechanical process compatible with the physiological environment. The SMH were synthesized by reaction of glycidylmethacrylated gelatin with oligo(ethylene glycol) (OEG) α,ω-dithiols of varying crosslinker length and amount. Triple helicalization of gelatin chains is shown directly by wide-angle X-ray scattering and indirectly via the mechanical behavior at different temperatures. The ability to form triple helices increased with the molar mass of the crosslinker. Hydrogels had storage moduli of 0.27–23 kPa and Young’s moduli of 215–360 kPa at 4 °C. The hydrogels were hydrolytically degradable, with full degradation to water-soluble products within one week at 37 °C and pH = 7.4. A thermally-induced shape-memory effect is demonstrated in bending as well as in compression tests, in which shape recovery with excellent shape-recovery rates Rr close to 100% were observed. In the future, the material presented here could be applied, e.g., as self-anchoring devices mechanically resembling the extracellular matrix.

scholarly journals Bio-Based Epoxy Shape-Memory Thermosets from Triglycidyl Phloroglucinol

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 542 ◽  
Author(s):  
David Santiago ◽  
Dailyn Guzmán ◽  
Francesc Ferrando ◽  
Àngels Serra ◽  
Silvia De la Flor
Keyword(s):  
Shape Memory ◽  
Shape Recovery ◽  
Memory Performance ◽  
Crosslinking Agent ◽  
Shape Memory Polymers ◽  
Crosslinking Density ◽  
Mechanical Analysis ◽  
Diglycidyl Ether ◽  
Partial Substitution ◽  
Scanning Calorimetry

A series of bio-based epoxy shape-memory thermosetting polymers were synthesized starting from a triglycidyl phloroglucinol (3EPOPh) and trimethylolpropane triglycidyl ether (TPTE) as epoxy monomers and a polyetheramine (JEF) as crosslinking agent. The evolution of the curing process was studied by differential scanning calorimetry (DSC) and the materials obtained were characterized by means of DSC, thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), stress-strain tests, and microindentation. Shape-memory properties were evaluated under free and totally constrained conditions. All results were compared with an industrial epoxy thermoset prepared from standard diglycidyl ether of Bisphenol A (DGEBA). Results revealed that materials prepared from 3EPOPh were more reactive and showed a tighter network with higher crosslinking density and glass transition temperatures than the prepared from DGEBA. The partial substitution of 3EPOPh by TPTE as epoxy comonomer caused an increase in the molecular mobility of the materials but without worsening the thermal stability. The shape-memory polymers (SMPs) prepared from 3EPOPh showed good mechanical properties as well as an excellent shape-memory performance. They showed almost complete shape-recovery and shape-fixation, fast shape-recovery rates, and recovery stress up to 7 MPa. The results obtained in this study allow us to conclude that the triglycidyl phloroglucinol derivative of eugenol is a safe and environmentally friendly alternative to DGEBA for preparing thermosetting shape-memory polymers.

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