Shape-memory Nanofiber Meshes with Programmable Cell Orientation

This paper reports a rational design of temperature-responsive nanofiber meshes with shape-memory effect. The meshes were fabricated by electrospinning a poly(ε-caprolactone) (PCL)-based polyurethane with different contents of soft and hard segments. The effects of PCL diol/hexamethylene diisocyanate (HDI)/1,4-butanediol (BD) molar ratio in terms of the contents of soft and hard segments on the shape-memory properties were investigated. Although the mechanical property improved with increasing hard segment ratio, optimal shape-memory properties were obtained with a PCL/HDI/BD molar ratio of 1:4:3. At a microscopic level, the original nanofibrous structure was easily deformed into a temporary shape, and recovered its original structure when the sample was reheated. A higher recovery rate (>89%) was achieved even when the mesh was deformed up to 400%. Finally, the nanofiber meshes were used to control the alignment of human mesenchymal stem cells (hMSCs). The hMSCs aligned well along the fiber orientation. The proposed nanofibrous meshes with the shape-memory effect have the potential to serve as in vitro platforms for the investigation of cell functions as well as implantable scaffolds for wound-healing applications.

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Shape-Memory Nanofiber Meshes with Programmable Cell Orientation

Fibers ◽

10.3390/fib7030020 ◽

2019 ◽

Vol 7 (3) ◽

pp. 20 ◽

Cited By ~ 4

Author(s):

Eri Niiyama ◽

Kanta Tanabe ◽

Koichiro Uto ◽

Akihiko Kikuchi ◽

Mitsuhiro Ebara

Keyword(s):

Mechanical Properties ◽

Shape Memory ◽

Rational Design ◽

Control Cell ◽

Hexamethylene Diisocyanate ◽

Molar Ratio ◽

Great Promise ◽

Original Structure ◽

Cell Alignment ◽

Shape Memory Properties

In this work we report the rational design of temperature-responsive nanofiber meshes with shape-memory properties. Meshes were fabricated by electrospinning poly(ε-caprolactone) (PCL)-based polyurethane with varying ratios of soft (PCL diol) and hard [hexamethylene diisocyanate (HDI)/1,4-butanediol (BD)] segments. By altering the PCL diol:HDI:BD molar ratio both shape-memory properties and mechanical properties could be readily turned and modulated. Though mechanical properties improved by increasing the hard to soft segment ratio, optimal shape-memory properties were obtained using a PCL/HDI/BD molar ratio of 1:4:3. Microscopically, the original nanofibrous structure could be deformed into and maintained in a temporary shape and later recover its original structure upon reheating. Even when deformed by 400%, a recovery rate of >89% was observed. Implementation of these shape memory nanofiber meshes as cell culture platforms revealed the unique ability to alter human mesenchymal stem cell alignment and orientation. Due to their biocompatible nature, temperature-responsivity, and ability to control cell alignment, we believe that these meshes may demonstrate great promise as biomedical applications.

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Synthesis and Characterization of IPDI Based Shape Memory Polyurethane

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1010.142 ◽

2020 ◽

Vol 1010 ◽

pp. 142-147

Author(s):

Nur Athirah Rasli @ Rosli ◽

Syazana Ahmad Zubir

Keyword(s):

Shape Memory ◽

Shape Memory Effect ◽

Memory Effect ◽

Soft Segment ◽

Shape Memory Polymer ◽

Palm Kernel ◽

Hexamethylene Diisocyanate ◽

Molar Ratio ◽

Scanning Calorimetry ◽

Chain Flexibility

Various polyurethane-based shape memory polymer was synthesized using polycaprolactone (PCL) as soft segment and, hexamethylene diisocyanate (HMDI) and isophorone diisocyanate (IPDI) as the hard segments. Palm kernel oil-based polyol was used to replace part of the petroleum-based polyol due to the increasing demand on renewable resources as a result of environmental awareness. The synthesis has been carried out using two step polymerization method. The effects of varying the molar ratio of IPDI/HMDI on material properties such as crystallinity, transition temperature, morphology, shape memory effect and tensile strength were investigated by using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), shape memory test and tensile test. A high IPDI content in SMPU results in better shape memory effect, whereas increasing HMDI content leads to a better chain flexibility. In this work, the incorporation of IPDI contributes to the formation of phase separation which enhance the formation of crystalline soft segment structure while the incorporation of HMDI as isocyanate tend to promote phase mixing which enhance the chain flexibility of the SMPU backbone.

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Multi-shape memory effect of polyimides with extremely high strain

RSC Advances ◽

10.1039/c7ra11399d ◽

2017 ◽

Vol 7 (84) ◽

pp. 53492-53496 ◽

Cited By ~ 7

Author(s):

Jianan Yao ◽

Zhao Zhang ◽

Chunbo Wang ◽

Shengqi Ma ◽

Tianqi Li ◽

...

Keyword(s):

Shape Memory ◽

Shape Memory Effect ◽

Memory Effect ◽

High Strain ◽

Synergistic Effects ◽

Shape Memory Properties ◽

Chemical Crosslinks ◽

Physical And Chemical

Polyimides exhibited high strain and multi-shape memory properties with the synergistic effects of physical and chemical crosslinks.

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Effect of Grain Refinement on Shape Memory Properties of Cu-Al-Mn SMAs

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1101.104 ◽

2015 ◽

Vol 1101 ◽

pp. 104-107 ◽

Cited By ~ 1

Author(s):

U.S. Mallik ◽

Vedamanickam Sampath

Keyword(s):

Grain Size ◽

Shape Memory ◽

Shape Memory Effect ◽

Memory Effect ◽

Compositional Analysis ◽

Tensile Tests ◽

Ingot Metallurgy ◽

Grain Refiner ◽

Shape Memory Properties ◽

Microstructural Examination

Cu-12.5 wt.% Al-5 wt.% Mn-(0.05 to 0.2) wt.% B alloys were prepared by ingot metallurgy. The Aluminum and Manganese contents of the alloys were maintained constant, while that of Boron was varied. The alloys were then characterized by subjecting them to compositional analysis, Differential Scanning Caloriemeter and microstructural examination. The shape memory effect and superelasticity of the alloys were determined by bend and tensile tests on the alloy specimens. The investigation reveals that Boron acts as a good grain refiner, resulting in a reduction of about 80% in grain size. The addition of Boron also increases the transformation temperatures by ~ 10oC, while at the same time decreasing the strain recovery by shape memory effect by 4%, and that by superelasticity by ~ 2%.

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The design of triple shape memory polymers with stable yet tunable temporary shapes by introducing photo-responsive units into a crystalline domain

Polymer Chemistry ◽

10.1039/c8py01810c ◽

2019 ◽

Vol 10 (12) ◽

pp. 1537-1543 ◽

Cited By ~ 2

Author(s):

Yongwei Wu ◽

Zhitao Hu ◽

Huahua Huang ◽

Yongming Chen

Keyword(s):

Shape Memory ◽

Shape Memory Effect ◽

Memory Effect ◽

Shape Memory Polymers ◽

Crystalline Domain ◽

Soft Segments ◽

Hard Segments ◽

Physically Crosslinked ◽

Triple Shape Memory

A desirable triple-shape memory effect showing stable yet easily tunable temporary shapes is achieved using a physically crosslinked network with photo-responsive coumarin-containing poly(ε-caprolactone) as soft segments and poly(l-lactide) as hard segments.

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Shape memory effect of poly(L-lactide)- based polyurethanes with different hard segments

Polymer International ◽

10.1002/pi.2204 ◽

2007 ◽

Vol 56 (7) ◽

pp. 840-846 ◽

Cited By ~ 38

Author(s):

Wenshou Wang ◽

Peng Ping ◽

Xuesi Chen ◽

Xiabin Jing

Keyword(s):

Shape Memory ◽

Shape Memory Effect ◽

Memory Effect ◽

Hard Segments

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Tensile Failure of 55-Nitinol Wire

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100113858 ◽

1975 ◽

Vol 33 ◽

pp. 46-47

Author(s):

F. I. Grace

Keyword(s):

Shape Memory ◽

Shape Memory Effect ◽

Memory Effect ◽

Stoichiometric Composition ◽

Tensile Failure ◽

Initial State ◽

Initial Shape ◽

Nitinol Wire ◽

Cscl Type ◽

Shear Transformation

An interest in NiTi alloys with near stoichiometric composition (55 NiTi) has intensified since they were found to exhibit a unique mechanical shape memory effect at the Naval Ordnance Laboratory some twelve years ago (thus refered to as NITINOL alloys). Since then, the microstructural mechanisms associated with the shape memory effect have been investigated and several interesting engineering applications have appeared.The shape memory effect implies that the alloy deformed from an initial shape will spontaneously return to that initial state upon heating. This behavior is reported to be related to a diffusionless shear transformation which takes place between similar but slightly different CsCl type structures.

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