scholarly journals Architectured Shape-Memory Hydrogels with Switching Segments Based on Oligo(ε-caprolactone)

MRS Advances ◽  
2016 ◽  
Vol 1 (27) ◽  
pp. 2011-2017 ◽  
Author(s):  
Maria Balk ◽  
Marc Behl ◽  
Ulrich Nöchel ◽  
Andreas Lendlein
Keyword(s):  
Shape Memory ◽  
Material Properties ◽  
Biomedical Applications ◽  
Polymer Networks ◽  
Hydrophilic Polymer ◽  
Potential Candidate ◽  
Thermal Crosslinking ◽  
Porous Microstructure ◽  
Image Position ◽  
Form Stability

ABSTRACTShape-memory hydrogels (SMHs) are potential candidate materials for biomedical applications as they can mimic the elastic properties of soft tissue and exhibit shape transformations at body temperature. Here we explored, whether architectured SMHs can be designed by incorporating oligo(ε-caprolactone) (OCL, ${\overline M _n}$ = 4500 g·mol-1, Tm = 54 °C) side chains as switching segment into hydrophilic polymer networks based on N-vinylpyrrolidone as backbone forming component and oligo(ethylene glycol)divinylether (OEGDVE, ${\overline M _n}$ = 250 g·mol-1) as crosslinker. By utilizing NaCl and NaHCO3 as porogene during thermal crosslinking architectured hydrogels having pore diameters between 30 and 500 µm and wall thicknesses ranging from 10 to 190 µm in the swollen state were synthesized. According to the porous microstructure, a macroscopic form stability was obtained when the polymer networks were swollen until equilibrium in water. Material properties were investigated as function of the OCL content, which was varied between 20 and 40 wt%. In compression experiments the architectured hydrogels exhibited strain fixity and strain recovery ratios above 80%. These architectured SMHs might enable biomaterial applications as smart implants with the recovery of bulky structures from compact shapes.

scholarly journals Shape-Memory Polymers for Biomedical Applications

2008 ◽  
Vol 54 ◽  
pp. 96-102 ◽  
Author(s):  
Andreas Lendlein ◽  
Marc Behl
Keyword(s):  
Shape Memory ◽  
Material Properties ◽  
Biomedical Applications ◽  
Traditional Approach ◽  
Shape Change ◽  
Shape Memory Polymers ◽  
Thermally Induced ◽  
Wide Range ◽  
Multifunctional Polymers ◽  
Suitable Process

Most polymers used in clinical applications today are materials that have been developed originally for application areas other than biomedicine. On the other side, different biomedical applications are demanding different combinations of material properties and functionalities. Compared to the intrinsic material properties, a functionality is not given by nature but result from the combination of the polymer architecture and a suitable process. Examples for functionalities that play a prominent role in the development of multifunctional polymers for medical applications are biofunctionality (e.g. cell or tissue specificity), degradability, or shape-memory functionality. In this sense, an important aim for developing multifunctional polymers is tailoring of biomaterials for specific biomedical applications. Here the traditional approach, which is designing a single new homo- or copolymer, reaches its limits. The strategy, that is applied here, is the development of polymer systems whose macroscopic properties can be tailored over a wide range by variation of molecular parameters. The Shape-memory capability of a material is its ability to trigger a predefined shape change by exposure to an external stimulus. A change in shape initiated by heat is called thermally-induced shape-memory effect. Thermally, light-, and magnetically induced shape-memory polymers will be presented, that were developed especially for minimally invasive surgery and other biomedical applications. Furthermore triple-shape polymers will be introduced, that have the capability to perform two subsequent shape changes. Thus enabling more complex movements of a polymeric material.

Modeling the Torsional Behavior of Superelastic Wires

2011 ◽  
Author(s):  
Zohreh Karbaschi ◽  
Mohammad Elahinia
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Material Properties ◽  
Biomedical Applications ◽  
Effect Of Temperature ◽  
Torsional Loading ◽  
Torsional Testing ◽  
Torsional Behavior ◽  
Niti Wires ◽  
Torque Angle

Torsional behavior of shape memory alloys can be employed in different biomedical applications. The goal of this paper is to investigate the behavior of these alloys under torsional loading conditions. To this end a torsional model is developed in MATLAB, in which a uniaxial model is extended to predict the torque-angle behavior of superelastic wires/rods. Tensile and torsional testing are performed on NiTi wires to determine martial properties and to verify this model. The material properties are determined based on ASTM standards. The effect of different parameters such as lengths and radii on the torque-angle behavior are investigated with the model. Moreover, the effect of temperature on the torsional behavior of SMA wires are presented.

Cellulose nanocrystals (CNC) reinforced shape memory polyurethane ribbons for future biomedical applications and design

2018 ◽  
Vol 33 (3) ◽  
pp. 377-392 ◽  
Author(s):  
Irina T Garces ◽  
Samira Aslanzadeh ◽  
Yaman Boluk ◽  
Cagri Ayranci
Keyword(s):  
Shape Memory ◽  
Cellulose Nanocrystals ◽  
Biomedical Applications ◽  
Flexural Modulus ◽  
Potential Candidate ◽  
The Past ◽  
Printing Cost ◽  
Surgical Sutures ◽  
Orthodontic Devices ◽  
Shape Memory Polyurethane

Shape memory materials are an innovative type of materials that reversibly store a temporary shape and recover back to the original dimensions with the application of an external mechanism such as heat. Shape memory polymers (SMP), specifically thermoplastic SMP (e.g. shape memory polyurethane (SMPU)) have received much attention during the past decade because of the promising future applications and advantages such as ease of processability for thermoplastic SMP (e.g. by 3-D printing), cost, and biocompatibility. In the biomedical field, applications such as stents, surgical sutures, and orthodontic devices, amongst others have been proposed. The addition of fillers to the material can modify the material to improve their load bearing capabilities. Bio-based fillers such as cellulose nanocrystals (CNC) have been proposed in a variety of reinforcing applications. The present work focuses on the experimental description of the addition of nonmodified CNC to SMPU. The work studied the effect on melt-extruded ribbons, for 0, 0.5, 1, 2, and 4 wt%. An increase of yield point, toughness, flexural modulus, recovery rate, and decrease of total time showed that SMPU/CNC nanocomposites are a potential candidate to use in future biomedical applications.

Optimizing the Thermomechanics of Shape-Memory Polymers for Biomedical Applications

2004 ◽  
Vol 855 ◽  
Author(s):  
Christopher M. Yakacki ◽  
Ken Gall ◽  
Robin Shandas ◽  
Alicia M. Ortega ◽  
Nick Willett ◽  
...  
Keyword(s):  
Shape Memory ◽  
Biomedical Applications ◽  
Shape Recovery ◽  
Polymer Networks ◽  
Shape Memory Polymers ◽  
Strain Recovery ◽  
Stress Recovery ◽  
High Deformation ◽  
Flexural Tests ◽  
Free Strain

ABSTRACTWe examine the shape-memory effect in polymer networks intended for biomedical applications. The polymers were photopolymerized from tert-butyl acrylate (tBA) with polyethyleneglycol dimethacrylate (PEGDMA) acting as a crosslinker. Three-point flexural tests were used to systematically investigate the thermomechanics of shape-storage deformation and shape recovery. The glass transition temperature (Tg) of the polymers varied over a range of 100°C and is dependent on the molecular weight and concentration of the crosslinker. The polymers show 100% strain recovery up to maximum strains of approximately 80% at low and high deformation temperatures (Td). Free strain recovery was determined to depend on the temperature during deformation; lower deformation temperatures (Td < Tg) decreased the temperature required for free strain recovery. Constrained stress recovery shows a complex evolution as a function of temperature and also depends on Td. The thermomechanical results are discussed in light of potential biomedical applications and a prototype stent that can be activated at body temperature is presented.

scholarly journals Laser additive manufacturing of bulk and porous shape-memory NiTi alloys: From processes to potential biomedical applications

MRS Bulletin ◽  
2016 ◽  
Vol 41 (10) ◽  
pp. 765-774 ◽  
Author(s):  
Sasan Dadbakhsh ◽  
Mathew Speirs ◽  
Jan Van Humbeeck ◽  
Jean-Pierre Kruth
Keyword(s):  
Additive Manufacturing ◽  
Shape Memory ◽  
Biomedical Applications ◽  
Laser Additive Manufacturing ◽  
Niti Alloys ◽  
Image Position

Abstract

Shape-Memory Hydrogels: Evolution of Structural Principles To Enable Shape Switching of Hydrophilic Polymer Networks

2017 ◽  
Vol 50 (4) ◽  
pp. 723-732 ◽  
Author(s):  
Candy Löwenberg ◽  
Maria Balk ◽  
Christian Wischke ◽  
Marc Behl ◽  
Andreas Lendlein
Keyword(s):  
Shape Memory ◽  
Polymer Networks ◽  
Hydrophilic Polymer ◽  
Structural Principles

scholarly journals Dynamic Semi IPNs with Duple Dynamic Linkers: Self-Healing, Reprocessing, Welding, and Shape Memory Behaviors

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1679
Author(s):  
Yanning Zeng ◽  
Weiming Yang ◽  
Shuxin Liu ◽  
Xiahui Shi ◽  
Aoqian Xi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Shape Memory ◽  
Material Properties ◽  
Dynamic Properties ◽  
Thermoplastic Polyurethane ◽  
Polymer Networks ◽  
Interpenetrating Polymer Networks ◽  
Diels Alder ◽  
Self Healing ◽  
Boronic Ester

Thermoset polymers show favorable material properties, while bringing about environmental pollution due to non-reprocessing and unrecyclable. Diels–Alder (DA) chemistry or reversible exchange boronic ester bonds have been employed to fabricate recycled polymers with covalent adaptable networks (CANs). Herein, a novel type of CANs with multiple dynamic linkers (DA chemistry and boronic ester bonds) was firstly constructed based on a linear copolymer of styrene and furfuryl methacrylate and boronic ester crosslinker. Thermoplastic polyurethane is introduced into the CANs to give a semi Interpenetrating Polymer Networks (semi IPNs) to enhance the properties of the CANs. We describe the synthesis and dynamic properties of semi IPNs. Because of the DA reaction and transesterification of boronic ester bonds, the topologies of semi IPNs can be altered, contributing to the reprocessing, self-healing, welding, and shape memory behaviors of the produced polymer. Through a microinjection technique, the cut samples of the semi IPNs can be reshaped and mechanical properties of the recycled samples can be well-restored after being remolded at 190 °C for 5 min.

scholarly journals Nanoengineering in biomedicine: Current development and future perspectives

2020 ◽  
Vol 9 (1) ◽  
pp. 700-715 ◽  
Author(s):  
Wei Jian ◽  
David Hui ◽  
Denvid Lau
Keyword(s):  
Molecular Dynamics ◽  
Research And Development ◽  
Molecular Dynamics Simulations ◽  
Material Properties ◽  
Biomedical Applications ◽  
Metallic Materials ◽  
Future Perspectives ◽  
Current Development ◽  
Materials Used ◽  
Dynamics Simulations

AbstractRecent advances in biomedicine largely rely on the development in nanoengineering. As the access to unique properties in biomaterials is not readily available from traditional techniques, the nanoengineering becomes an effective approach for research and development, by which the performance as well as the functionalities of biomaterials has been greatly improved and enriched. This review focuses on the main materials used in biomedicine, including metallic materials, polymers, and nanocomposites, as well as the major applications of nanoengineering in developing biomedical treatments and techniques. Research that provides an in-depth understanding of material properties and efficient enhancement of material performance using molecular dynamics simulations from the nanoengineering perspective are discussed. The advanced techniques which facilitate nanoengineering in biomedical applications are also presented to inspire further improvement in the future. Furthermore, the potential challenges of nanoengineering in biomedicine are evaluated by summarizing concerned issues and possible solutions.

The Ti3.6Nb1.0Ta0.2Zr0.2 coating of anodized aluminum by PVD: A potential candidate for short-time biomedical applications

Vacuum ◽  
2021 ◽  
pp. 110450
Author(s):  
M. Zarka ◽  
B. Dikici ◽  
M. Niinomi ◽  
K.V. Ezirmik ◽  
M. Nakai ◽  
...  
Keyword(s):  
Biomedical Applications ◽  
Potential Candidate ◽  
Anodized Aluminum ◽  
Short Time

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.

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