Structural tuning of polycaprolactone based thermadapt shape memory polymer

Shape memory polymers can provide excellent bonding property because of their shape memory effects. This paper proposes an adhesive unit that is capable of repeatable smart adhesion and exhibits reversible adhesion under heating.

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Structural multi-colour invisible inks with submicron 4D printing of shape memory polymers

Nature Communications ◽

10.1038/s41467-020-20300-2 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Wang Zhang ◽

Hao Wang ◽

Hongtao Wang ◽

John You En Chan ◽

Hailong Liu ◽

...

Keyword(s):

Shape Memory ◽

Information Hiding ◽

Shape Memory Polymer ◽

Shape Memory Polymers ◽

Photonic Devices ◽

Temperature Sensitive ◽

4D Printing ◽

Two Photon ◽

Shape Memory Effects ◽

Nanoscale Structure

AbstractFour-dimensional (4D) printing of shape memory polymer (SMP) imparts time responsive properties to 3D structures. Here, we explore 4D printing of a SMP in the submicron length scale, extending its applications to nanophononics. We report a new SMP photoresist based on Vero Clear achieving print features at a resolution of ~300 nm half pitch using two-photon polymerization lithography (TPL). Prints consisting of grids with size-tunable multi-colours enabled the study of shape memory effects to achieve large visual shifts through nanoscale structure deformation. As the nanostructures are flattened, the colours and printed information become invisible. Remarkably, the shape memory effect recovers the original surface morphology of the nanostructures along with its structural colour within seconds of heating above its glass transition temperature. The high-resolution printing and excellent reversibility in both microtopography and optical properties promises a platform for temperature-sensitive labels, information hiding for anti-counterfeiting, and tunable photonic devices.

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Shape Memory Behavior of Carbon Composites With Functional Interlayer

Volume 2: Materials; Joint MSEC-NAMRC-Manufacturing USA ◽

10.1115/msec2018-6449 ◽

2018 ◽

Cited By ~ 1

Author(s):

L. Santo ◽

L. Iorio ◽

G. M. Tedde ◽

F. Quadrini

Keyword(s):

Carbon Fiber ◽

Shape Memory ◽

Polymer Composites ◽

Polymer Matrix ◽

Smart Materials ◽

Shape Memory Polymer ◽

Shape Memory Polymers ◽

Carbon Composites ◽

Three Point Bending ◽

Functional Behavior

Shape Memory Polymer Composites (SMPCs) are smart materials showing the structural properties of long-fiber polymer-matrix together with the functional behavior of shape memory polymers. In this study, SM carbon fiber reinforced (CFR) composites have been produced by using a SM interlayer between two CFR prepregs. Their SM properties have been evaluated in comparison with traditional structural CFR composites without the SM interlayer by using an especially designed test. Active and frozen forces are measured during a thermo-mechanical cycle in the three-point bending configuration. Experimental results show that SMPCs are able to fix a temporary deformed shape by freezing high stresses.

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Shape-Memory Polymeric Artificial Muscles: Mechanisms, Applications and Challenges

Molecules ◽

10.3390/molecules25184246 ◽

2020 ◽

Vol 25 (18) ◽

pp. 4246 ◽

Cited By ~ 1

Author(s):

Yujie Chen ◽

Chi Chen ◽

Hafeez Ur Rehman ◽

Xu Zheng ◽

Hua Li ◽

...

Keyword(s):

Shape Memory ◽

Smart Materials ◽

Recent Progress ◽

Shape Memory Polymer ◽

Shape Memory Polymers ◽

Artificial Muscles ◽

Linkage Design ◽

Wide Range ◽

Liquid Crystal Elastomers ◽

Made In

Shape-memory materials are smart materials that can remember an original shape and return to their unique state from a deformed secondary shape in the presence of an appropriate stimulus. This property allows these materials to be used as shape-memory artificial muscles, which form a subclass of artificial muscles. The shape-memory artificial muscles are fabricated from shape-memory polymers (SMPs) by twist insertion, shape fixation via Tm or Tg, or by liquid crystal elastomers (LCEs). The prepared SMP artificial muscles can be used in a wide range of applications, from biomimetic and soft robotics to actuators, because they can be operated without sophisticated linkage design and can achieve complex final shapes. Recently, significant achievements have been made in fabrication, modelling, and manipulation of SMP-based artificial muscles. This paper presents a review of the recent progress in shape-memory polymer-based artificial muscles. Here we focus on the mechanisms of SMPs, applications of SMPs as artificial muscles, and the challenges they face concerning actuation. While shape-memory behavior has been demonstrated in several stimulated environments, our focus is on thermal-, photo-, and electrical-actuated SMP artificial muscles.

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Chemical Modifications of Porous Shape Memory Polymers for Enhanced X-ray and MRI Visibility

Molecules ◽

10.3390/molecules25204660 ◽

2020 ◽

Vol 25 (20) ◽

pp. 4660

Author(s):

Grace K. Fletcher ◽

Landon D. Nash ◽

Lance M. Graul ◽

Lindy K. Jang ◽

Scott M. Herting ◽

...

Keyword(s):

Shape Memory ◽

Medical Devices ◽

Shape Memory Polymer ◽

Shape Memory Polymers ◽

Tissue Scaffolds ◽

Resonance Imaging ◽

Clinical Imaging ◽

X Ray ◽

Device Development ◽

Magnetic Resonance Imaging Mri

The goal of this work was to develop a shape memory polymer (SMP) foam with visibility under both X-ray and magnetic resonance imaging (MRI) modalities. A porous polymeric material with these properties is desirable in medical device development for applications requiring thermoresponsive tissue scaffolds with clinical imaging capabilities. Dual modality visibility was achieved by chemically incorporating monomers with X-ray visible iodine-motifs and MRI visible monomers with gadolinium content. Physical and thermomechanical characterization showed the effect of increased gadopentetic acid (GPA) on shape memory behavior. Multiple compositions showed brightening effects in pilot, T1-weighted MR imaging. There was a correlation between the polymeric density and X-ray visibility on expanded and compressed SMP foams. Additionally, extractions and indirect cytocompatibility studies were performed to address toxicity concerns of gadolinium-based contrast agents (GBCAs). This material platform has the potential to be used in a variety of medical devices.

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Developing a beam formulation for semi-crystalline two-way shape memory polymers

Journal of Intelligent Material Systems and Structures ◽

10.1177/1045389x20924837 ◽

2020 ◽

Vol 31 (12) ◽

pp. 1465-1476

Author(s):

Mohammad-Ali Maleki-Bigdeli ◽

Majid Baniassadi ◽

Kui Wang ◽

Mostafa Baghani

Keyword(s):

Finite Element ◽

Shape Memory ◽

Shape Memory Polymer ◽

Beam Theory ◽

Shape Memory Polymers ◽

Bernoulli Beam ◽

Von Karman ◽

Von Kármán ◽

Euler Bernoulli Beam ◽

Beam Theories

In this research, the bending of a two-way shape memory polymer beam is examined implementing a one-dimensional phenomenological macroscopic constitutive model into Euler–Bernoulli and von-Karman beam theories. Since bending loading is a fundamental problem in engineering applications, a combination of bending problem and two-way shape memory effect capable of switching between two temporary shapes can be used in different applications, for example, thermally activated sensors and actuators. Shape memory polymers as a branch of soft materials can undergo large deformation. Hence, Euler–Bernoulli beam theory does not apply to the bending of a shape memory polymer beam where moderate rotations may occur. To overcome this limitation, von-Karman beam theory accounting for the mid-plane stretching as well as moderate rotations can be employed. To investigate the difference between the two beam theories, the deflection and rotating angles of a shape memory polymer cantilever beam are analyzed under small and moderate deflections and rotations. A semi-analytical approach is used to inspect Euler–Bernoulli beam theory, while finite-element method is employed to study von-Karman beam theory. In the following, a smart structure is analyzed using a prepared user-defined subroutine, VUMAT, in finite-element package, ABAQUS/EXPLICIT. Utilizing generated user-defined subroutine, smart structures composed of shape memory polymer material can be analyzed under complex loading circumstances through the two-way shape memory effect.

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A comprehensive review on thermomechanical constitutive models for shape memory polymers

Journal of Intelligent Material Systems and Structures ◽

10.1177/1045389x20916795 ◽

2020 ◽

Vol 31 (10) ◽

pp. 1243-1283 ◽

Cited By ~ 4

Author(s):

Ebrahim Yarali ◽

Ali Taheri ◽

Mostafa Baghani

Keyword(s):

Shape Memory ◽

Smart Materials ◽

Constitutive Equations ◽

Constitutive Relations ◽

Shape Memory Polymer ◽

Constitutive Models ◽

Shape Memory Polymers ◽

Typical Application ◽

Comprehensive Review ◽

Thermally Responsive

Shape memory polymers are a class of smart materials, which are capable of fixing their deformed shapes, and can return to their original shape in reaction to external stimulus such as heat. Also due to their exceptional properties, they are mostly used in four-dimensional printing applications. To model and investigate thermomechanical response of shape memory polymers mathematically, several constitutive equations have been developed over the past two decades. The purpose of this research is to provide an up-to-date review on structures, classifications, applications of shape memory polymers, and constitutive equations of thermally responsive shape memory polymers and their composites. First, a comprehensive review on the properties, structure, and classifications of shape memory polymers is conducted. Then, the proposed models in the literature are presented and discussed, which, particularly, are focused on the phase transition and thermo-viscoelastic approaches for conventional, two-way as well as multi-shape memory polymers. Then, a statistical analysis on constitutive relations of thermally activated shape memory polymers is carried out. Finally, we present a summary and give some concluding remarks, which could be helpful in selection of a suitable shape memory polymer constitutive model under a typical application.

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Thermo-Mechanical Behavior of Epoxy Shape Memory Polymer

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.721.169 ◽

2013 ◽

Vol 721 ◽

pp. 169-172 ◽

Cited By ~ 2

Author(s):

Yu Gu ◽

Shao Xiong Li

Keyword(s):

Mechanical Behavior ◽

Shape Memory ◽

Significant Influence ◽

Smart Materials ◽

Shape Memory Polymer ◽

Shape Memory Polymers ◽

Testing Temperature ◽

Curing Agent ◽

Different Temperatures ◽

Viscoelastic Behaviors

The viscoelastic behaviors of shape memory polymers have a significant influence on the function realization of this kind of smart materials. In this study, stress-strain hysteresis under uniaxial tension of epoxy shape memory polymers with varied curing agent contents and types were tested at different temperatures. The effects of the testing temperature, curing-agent type and content on the viscoelastic behaviors of the materials were discussed.

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A constitutive model for shape memory polymers with application to torsion of prismatic bars

Journal of Intelligent Material Systems and Structures ◽

10.1177/1045389x11431745 ◽

2012 ◽

Vol 23 (2) ◽

pp. 107-116 ◽

Cited By ~ 35

Author(s):

Mostafa Baghani ◽

Reza Naghdabadi ◽

Jamal Arghavani ◽

Saeed Sohrabpour

Keyword(s):

Heat Transfer ◽

Constitutive Model ◽

Shape Memory ◽

Shape Memory Polymer ◽

Shape Memory Polymers ◽

Second Law Of Thermodynamics ◽

Considerable Effect ◽

Heat Transfer Analysis ◽

Internal Variables ◽

Rate Dependent

In this article, satisfying the second law of thermodynamics, we present a 3D constitutive model for shape memory polymers. The model is based on an additive decomposition of the strain into four parts. Also, evolution laws for internal variables during both cooling and heating processes are proposed. Since temperature has considerable effect on the shape memory polymer behavior, for simulation of a shape memory polymer–based structure, it is required to perform a heat-transfer analysis. Commonly, an experimentally observed temperature rate–dependent behavior of shape memory polymers is justified by a rate-dependent glassy temperature, but using the heat-transfer analysis, it is shown that the glassy temperature could be considered as a constant material parameter. To this end, implementing the constitutive model within a nonlinear finite element code, we simulate torsion of a shape memory polymer rectangular bar and a circular tube. Moreover, we compare the predicted results with experimental data recently reported in the literature, which shows a good agreement.

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Application of a Constitutive Modeling for Light Activated Shape Memory Polymer to Circular Shear

Volume 8: Mechanics of Solids, Structures and Fluids ◽

10.1115/imece2012-86892 ◽

2012 ◽

Author(s):

Fangda Cui ◽

I. J. Rao

Keyword(s):

Shape Memory ◽

Constitutive Modeling ◽

Shape Memory Polymer ◽

Shape Memory Polymers ◽

Polymer Chains ◽

Covalent Bonds ◽

The Past ◽

Original Shape ◽

Multiple Natural Configurations ◽

New Type

Shape memory polymers (SMP’s) are polymers that have the ability to retain a temporary shape, which can revert back to the original shape on exposure to specific triggers such as increase in temperature or exposure to light at specific wavelengths. A new type of shape memory polymer, light activated shape memory polymers (LASMP’s) have been developed in the past few years. In these polymers the temporary shapes are fixed by exposure to light at a specific wavelength. Exposure to light at this wavelength causes the photosensitive molecules, which are grafted on to the polymer chains, to form covalent bonds. These covalent bonds are responsible for the temporary shape and act as crosslinks. On exposure to light at a different wavelength these bonds are cleaved and the material can revert back to its original shape. A constitutive model of LASMP’s which based on the notion of multiple natural configurations has been developed (see Sodhi and Rao[1]). In this work we use this model to analyze the mechanical behavior of LASMP’s under a specific boundary value problem, namely, the problem of circular shear. We use this model problem to study the behavior of the LASMP’s when a temporary configuration is formed by exposing the polymer to light. In addition we show that these materials are able to undergo complex cycles of deformation due to the flexibility with which these temporary configurations can be formed and removed by exposure to light.

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