scholarly journals Bio-inspired and computer-supported design of modulated shape changes in polymer materials

2021 ◽  
Author(s):  
Johan Bäckemo ◽  
Yue Liu ◽  
Andreas Lendlein
Keyword(s):  
Shape Memory ◽  
Shape Memory Polymers ◽  
Digital Design ◽  
Polymer Materials ◽  
Digital Manufacturing ◽  
Stable States ◽  
Venus Flytrap ◽  
Poly Ethylene ◽  
Constraint Model ◽  
Shape Changes

Abstract The Venus flytrap is a fascinating plant with a finely tuned mechanical bi-stable system, which can switch between mono- and bi-stability. Here, we combine geometrical design of compliant mechanics and the function of shape-memory polymers to enable switching between bi- and mono-stable states. Digital design and modelling using the Chained Beam Constraint Model forecasted two geometries, which were experimentally realized as structured films of cross-linked poly[ethylene-co-(vinyl acetate)] supported by digital manufacturing. Mechanical evaluation confirmed our predicted features. We demonstrated that a shape-memory effect could switch between bi- and mono-stability for the same construct, effectively imitating the Venus flytrap. Graphic Abstract

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.

Characterizations of Silicon Carbide Whisker-Filled in Benzoxazine-Epoxy Shape Memory Polymers

2015 ◽  
Vol 659 ◽  
pp. 373-377 ◽  
Author(s):  
Chutiwat Likitaporn ◽  
Sarawut Rimdusit
Keyword(s):  
Silicon Carbide ◽  
Shape Memory ◽  
Polymer Composites ◽  
Binary Systems ◽  
Glassy State ◽  
Shape Memory Polymer ◽  
Shape Memory Polymers ◽  
Polymer Materials ◽  
External Stimulation ◽  
Silicon Carbide Whisker

Shape memory polymers (SMPs) are polymer materials that can fix the temporary shape and then recover to their original permanent shape by external stimulation, i.e. applied heat. In this research, shape memory polymer composites (SMPCs) from benzoxazine (BA-a)-epoxy binary systems reinforced with adamantine silicon carbide whisker (SiCw) are investigated. The SiCw contents are controlled to be in range of 0 to 15% by weight. All specimens were fabricated by compression molding technique. The results revealed that the shape memory polymer composites showed higher glassy state storage modulus with increasing amount of the whisker suggesting substantial reinforcement effect of the whisker used. The glass transition temperature (Tg) was also improved from 102°C of the based polymer to the value about 122°C with the addition of about 15% by weight of the silicon carbide whisker. Finally, shape recovery stress systematically increased from the value about 1.5MPa of the unfilled polymer matrix to the value about 3.2MPa with an addition of 15% by weight of the silicon carbide whisker. The positive effect on thermal stability from SiCw addition is expected from the modification and will be reported in this work.

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

A Thermo-Mechanical Constitutive Model of Glassy Shape Memory Polymers

2016 ◽  
Vol 853 ◽  
pp. 96-100 ◽  
Author(s):  
Jian Li ◽  
Shi Yu Dong ◽  
Qian Hua Kan ◽  
Guo Zheng Kang ◽  
Wen Yi Yan
Keyword(s):  
Constitutive Model ◽  
Shape Memory ◽  
Evolution Equations ◽  
Model Simulation ◽  
Shape Memory Polymer ◽  
Three Dimensional ◽  
Shape Memory Polymers ◽  
Nonlinear Evolution Equations ◽  
Polymer Materials ◽  
Extended Model

Glassy shape memory polymer materials are applied successfully in biomedical fields due to their large recovery deformation, excellent biocompatibility and unique biodegradability. To predict the thermo-mechanical behavior of glassy shape memory polymers in biomedical devices accurately, a reasonably three-dimensional thermo-mechanical constitutive model must be established firstly. A one-dimensional linear-elastic constitutive model proposed by Tobushi et. al. (1997) was extended to capture the loading level dependent degradation of shape memory effect by introducing new nonlinear evolution equations with threshold values. Comparisons between experiments and simulations were carried to validate the extended model. Simulation results agree with experiments well, especially for the high loading levels.

Tissue Integration of Two Different Shape-Memory Polymers with Poly(ε-Caprolactone) Switching Segment in Rats

2008 ◽  
Author(s):  
Bernhard Hiebl ◽  
Dorothee Rickert ◽  
Rosemarie Fuhrmann ◽  
Friedrich Jung ◽  
Andres Lendlein ◽  
...  
Keyword(s):  
Shape Memory ◽  
Shape Memory Polymers ◽  
Tissue Integration
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