Shape-Memory Properties of Segmented Polymers Containing Aramid Hard Segments and Polycaprolactone Soft Segments

The effect of substrate chemistry on surface phase separation of polyurethane films were investigated by using self-assembled monolayer (SAM) with chemically different modifications, i.e. hydroxy (–OH) and methyl (–CH3) end groups. Results showed that hydrophilic (–OH) and hydrophobic end groups (–CH[Formula: see text] could respectively promote the aggregation of hard and soft segments at polyurethane–substrate interface, which further regulates the phase separation of polyurethane surface that contacts the substrate. The aggregation of hard segments tended to enhance the surface smoothness of polyurethane films, especially on hydrophilic substrates with hydroxy modification. Further analysis of tensile testing revealed that the regulation of surface phase separation had no effect on the shape memory effect of polyurethane films. These findings suggest that the chemical properties of the substrates could regulate the phase separation and may provide some guidance on the design of specific polyurethane with desired morphology and properties.

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Structure and Shape Memory Properties of Polyurethane Copolymers Having Urethane Chains as Soft Segments

Journal of Macromolecular Science Part B ◽

10.1080/00222348.2011.562091 ◽

2011 ◽

Vol 50 (12) ◽

pp. 2290-2306 ◽

Cited By ~ 8

Author(s):

Feng Long Ji ◽

Jin Lian Hu ◽

Wing-Man Winnie Yu ◽

Stephen Sin-Yin Chiu

Keyword(s):

Shape Memory ◽

Soft Segments ◽

Shape Memory Properties

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Synthesis and characterization of two shape-memory polymers containing short aramid hard segments and poly(ε-caprolactone) soft segments

Polymer ◽

10.1016/j.polymer.2006.03.106 ◽

2006 ◽

Vol 47 (12) ◽

pp. 4251-4260 ◽

Cited By ~ 74

Author(s):

Gouher Rabani ◽

Heinrich Luftmann ◽

Arno Kraft

Keyword(s):

Shape Memory ◽

Shape Memory Polymers ◽

Synthesis And Characterization ◽

Soft Segments ◽

Hard Segments

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Understanding the shape memory behavior of thermoplastic polyurethane elastomers with coarse-grained molecular dynamics simulations

MRS Advances ◽

10.1557/adv.2017.11 ◽

2017 ◽

Vol 2 (6) ◽

pp. 375-380 ◽

Cited By ~ 2

Author(s):

Md Salah Uddin ◽

Jaehyung Ju

Keyword(s):

Molecular Dynamics ◽

Shape Memory ◽

Shape Recovery ◽

Thermoplastic Polyurethane ◽

Coarse Grained ◽

Polyurethane Elastomers ◽

Weight Percentage ◽

Shape Memory Behavior ◽

Soft Segments ◽

Hard Segments

ABSTRACTWe perform molecular dynamics (MD) simulations to understand thermally triggered shape memory behavior of a thermoplastic polyurethane (TPU) elastomer with an enhanced coarse-grained (CG) model. Hard and soft phases of shape memory polymers (SMPs) are known as fixed and reversible phase, respectively. Fixity depends on the content of hard segments due to their restricted mobility. On the contrary, recovery depends on the dynamic motion of the soft segments as well the degree of cross-linking, which is also affected by the quantity of hard segment. Several CG models of the TPU are constructed varying the weight percentage of soft segments to observe their effects on shape recovery and fixity. All of the models are equilibrated at 300K (above glass transition, Tg: 200-250 K) and deformed under uniaxial loading with NPT (isothermal-isobaric) ensembles. The deformed state is cooled to 100K (below Tg) and further equilibrated to estimate the shape fixity. Shape recovery is predicted by heating and equilibrating the structures back to 300K. By the end of this study, we may answer how much the shape fixities and recoveries are changed for varying concentration of hard segments from thermomechanical cycles with CGMD simulations.

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Shape-memory Nanofiber Meshes with Programmable Cell Orientation

10.20944/preprints201811.0585.v1 ◽

2018 ◽

Author(s):

Eri Niiyam ◽

Kanta Tanabe ◽

Koichiro Uto ◽

Akihiko Kikuchi ◽

Mitsuhiro Ebara

Keyword(s):

Shape Memory ◽

Shape Memory Effect ◽

Memory Effect ◽

Rational Design ◽

Hexamethylene Diisocyanate ◽

Molar Ratio ◽

Original Structure ◽

Cell Functions ◽

Shape Memory Properties ◽

Hard Segments

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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