scholarly journals Thermally-Induced Shape-Memory Behavior of Degradable Gelatin-Based Networks

2021 ◽  
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 as multifunctional, actively-moving polymers of interest in biomedicine. In loosely crosslinked polymer networks gelatin chains may form triple helices, which can act as temporary netpoints 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 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.

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.

Smart Materials of Cured Epoxy Polymer Modified by 6F-PEEK with Shape Memory Effect

2010 ◽  
Vol 152-153 ◽  
pp. 530-535 ◽  
Author(s):  
Jun Peng Gao ◽  
Chen Qian Zhang ◽  
Xian Cheng He ◽  
Hong Yi Ma ◽  
Xue Feng An ◽  
...  
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Smart Materials ◽  
Shape Recovery ◽  
Epoxy Polymer ◽  
Memory Effects ◽  
Retention Rates ◽  
Thermally Induced ◽  
Shape Memory Effects

We demonstrated a method of fabricating thermosetting epoxy polymer with shape memory effect modified Poly (ether ether ketone) (6F-PEEK) based on the formation of a phase-segregated morphology. The peculiarities of shape memory effects of the epoxy resin modified by 6F-PEEK were investigated. DMA result showed two glass transition temperatures in this blended material. The cured epoxy phase showing high Tg of 223oC acted as hard-segment-forming phase the and was responsible for the permanent shape. The 6F-PEEK can be used as switching phase for a thermally induced shape-memory effect. The transition temperature (Ttran) was 150oC, which was between the Tg of cured epoxy and 6F-PEEK. At the special concentrations of 6F-PEEK, the shape memory effect accompanied by a significant increase in volume was observed. The highest shape memory effect was obtained for the blended material with 25.00 wt% of 6F-PEEK. The shape retention rates and the shape recovery rates were 96-99% and 100%, respectively. The times of shape-recovery were all defined in 2 min. The mechanism of shape memory effects and the mechanical properties of the cured resin were discussed.

scholarly journals Influence of Compression Direction on the Shape-Memory Effect of Micro-Cylinder Arrays Prepared from Semi-Crystalline Polymer Networks

MRS Advances ◽  
2016 ◽  
Vol 1 (27) ◽  
pp. 1985-1993 ◽  
Author(s):  
Yi Jiang ◽  
Liang Fang ◽  
Karl Kratz ◽  
Andreas Lendlein
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Shape Recovery ◽  
Shape Change ◽  
Memory Performance ◽  
Polymer Networks ◽  
Crystalline Polymer ◽  
Complete Recovery ◽  
Compression Direction

ABSTRACTMicrostructured polymeric surfaces capable of a thermally-induced shape-memory effect (SME) can perform on demand changes of surface properties such as wettability or adhesion.In this study, we explored the influence of the applied compression direction during programming, i.e. vertical compression and tilted compression, on the SME of microstructured crosslinked poly[ethylene-co-(vinyl acetate)] (cPEVA) films comprising arrays of micro-cylinders with a height of 10 µm and different diameters of 10 µm, 25 µm, and 50 µm. The shape recovery of the microstructures during heating was visualized online by optical microscopy, while atomic force microscopy (AFM) was utilized to investigate the temperature-induced shape change of single micro-cylinders. Here, the changes in micro-cylinder height and the characteristic angle θ were followed and analyzed for quantification of the shape-memory performance. Both compression modes resulted in almost flat programmed surfaces as indicated by high shape fixity ratios of Rf ≥ 93±1%. A nearly complete recovery of the micro-cylinders was obtained for all investigated cPEVA samples documented by high shape recovery values of Rr ≥ 97±1%, while the obtained shape change of the micro-cylinders during recovery almost reversely recalled the applied deformation during programming. The presented capability of SMP microstructured substrates to memorize the way of deformation during programming could be a new tool for controlling particular shape changes of microstructures during recovery and in such a way the generated local recovery forces can be adjusted.

Shape Memory Effect of Polycrystalline Ni54Mn25Ga17.5Ta0.5 High Temperature Shape Memory Alloy with Wide Hysteresis Loop

2020 ◽  
Vol 837 ◽  
pp. 35-40
Author(s):  
Shun Yao Hui ◽  
Chao Ran Li ◽  
Tong Wang ◽  
Jing Wei Xie ◽  
Gui Fu Dong
Keyword(s):  
Shape Memory ◽  
Hysteresis Loop ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Shape Recovery ◽  
Lath Martensite ◽  
Martensitic Transition ◽  
Compression Tests ◽  
Wide Hysteresis ◽  
Martensite Structure

Effect of Ta-alloying on microstructure, martensitic transformation, mechanical property and shape memory effect of Ni54Mn25Ga17.5Ta0.5 alloy has been systematically investigated. The results show that the substructure of Ni-Mn-Ga alloy significantly changed, which was converted from the plate martensite to the lath martensite. Compression tests show that a compressive strength of 1380 MPa with a fracture strain up to 21.92% can be achieved in the Ni54Mn25Ga17.5Ta0.5 alloy at room temperature. This is no changed martensite structure with non-modulated T martensite. In addition, the martensitic transition temperature obviously decreases from 350 °C to 208 °Cand hysteresis loop increases about 20 °Cwhen Ta substituted of Ni. The shape memory effect increased with the increase of pre-deformation, nevertheless, the shape recovery ratio appeared firstly increases and then decreases. When the pre-deformation is 10%, 15%, 20%, the shape memory effect of the alloy is 5.1%, 6.8% and 10%, respectively.

Relationship between Annealing and Shape Memory Effect of Shape Memory Polyurethane

2014 ◽  
Vol 936 ◽  
pp. 140-144 ◽  
Author(s):  
Jia Ying ◽  
Masaaki Nishikawa ◽  
Masaki Hojo
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Shape Recovery ◽  
Length Change ◽  
Recovery Ratio ◽  
High Entropy ◽  
Change Of State ◽  
Relationship Of ◽  
Shape Memory Polyurethane

The relationship of annealing and shape memory effect of uniaxially oriented shape memory polyurethane was studied; meanwhile a new method of adjusting shape recovery ratio by annealing was proposed for further consideration. Experiments were designed to compare the influence on length change from annealing and shape memory effect with shape memory polyurethane film at 65°C. We found that for shape memory polyurethane which had residual strain from material processing procedure, annealing and shape memory effect have the same effect on its length change if they are both carried out at the same temperature. It is because annealing and shape memory effect have the same mechanism, which is the change of state from low conformational entropy states to the recovery of a stable high entropy state in the polymer. Moreover, it is proved by experiment that shape recovery ratio of shape memory polyurethane can be adjusted by annealing.

Effect of Tin Addition on Phase Constitution and Heat Treatment Behavior in Ti-40Ta-Sn Alloys

2004 ◽  
Vol 449-452 ◽  
pp. 1273-1276 ◽  
Author(s):  
Masahiko Ikeda ◽  
S. Komatsu ◽  
Yuichiro Nakamura ◽  
Y. Kobayashi
Keyword(s):  
Heat Treatment ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Shape Recovery ◽  
Resistivity Ratio ◽  
Phase Constitution ◽  
Recovery Test ◽  
Orthorhombic Martensite ◽  
Solution Treated

Using Ti-40mass%Ta-0, -4, -8 and -12mass%Sn alloys, the effect of Sn addition on phase constitution in the solution treated and quenched state and isochronal heat treatment behavior is studied by electrical resistivity and Vickers hardness measurements and X-ray diffactometry. To confirm shape memory effect of some of these alloys, shape-recovery test was also performed. Orthorhombic martensite, ” was identified in Ti-40Sn-0 to 8Sn alloy quenched from 1173K, while phase was identified in STQed Ti-40Ta-12Sn alloy. On isochronal heat treatment, increases of resistivity at LN and resistivity ratio were observed in only 8Sn alloy, because these increases are due to reverse-transformation of ” to phase. From result of shape recovery test, shape memory effect was observed in Ti-40Ta-4 and 8Sn alloys

Effect of Aging on Mechanical Properties of Ti-Mo-Al Biomedical Shape Memory Alloy

2010 ◽  
Vol 654-656 ◽  
pp. 2150-2153 ◽  
Author(s):  
Hideki Hosoda ◽  
Makoto Taniguchi ◽  
Tomonari Inamura ◽  
Hiroyasu Kanetaka ◽  
Shuichi Miyazaki
Keyword(s):  
Mechanical Properties ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Shape Recovery ◽  
Tensile Tests ◽  
Single Step ◽  
Two Phase ◽  
Solution Treated

Effects of single- and multi-step aging on mechanical properties and shape memory properties of Ti-6Mo-8Al (mol%) biomedical shape memory alloy were studied using tensile tests at room temperature (RT). The solution-treated alloy at RT was two phase of bcc β and martensite α". Tensile tests revealed that the solution-treated alloy exhibited good shape memory effect. As for the single-step aging, (1) pseudoelastic shape recovery by unloading was observed after aging at 623K, (2) the alloy became brittle after aging at 773K due to ω embrittlement, and (3) strength was improved with small shape memory effect by aging at 1023K. On the other hand, after a multistep aging at 773K-1023K-1123K, the alloy was strengthened and showed perfect shape recovery. The improvement must be achieved by the formation of fine and uniform hcp α precipitates.

Study on the Shape Memory Behavior of Poly (L-Lactide)

2005 ◽  
Vol 475-479 ◽  
pp. 2399-2402 ◽  
Author(s):  
Xili Lu ◽  
Wei Cai ◽  
Lian Cheng Zhao
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Amorphous Phase ◽  
Memory Effect ◽  
Crystalline Phase ◽  
Ring Opening ◽  
Shape Recovery ◽  
Ring Opening Polymerization ◽  
Bending Test ◽  
Shape Memory Behavior

Poly(L-lactide) (PLLA) was synthesized by the ring-opening polymerization of L-lactide and the shape memory behavior was studied using DSC and bending test experiments. The results indicate that the specimen shows the shape memory effect (SME), the small crystalline phase of PLLA and the mobility of amorphous phase may be responsible for the SME. The shape recovery of samples decreases and approaches to steady with the testing number increases.

scholarly journals Investigations of Effects of Intermetallic Compound on the Mechanical Properties and Shape Memory Effect of Ti–Au–Ta Biomaterials

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5810
Author(s):  
Wan-Ting Chiu ◽  
Kota Fuchiwaki ◽  
Akira Umise ◽  
Masaki Tahara ◽  
Tomonari Inamura ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Intermetallic Compound ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Shape Recovery ◽  
Population Aging ◽  
Chemical Compositions ◽  
Physical Metallurgy ◽  
World Population

Owing to the world population aging, biomedical materials, such as shape memory alloys (SMAs) have attracted much attention. The biocompatible Ti–Au–Ta SMAs, which also possess high X–ray contrast for the applications like guidewire utilized in surgery, were studied in this work. The alloys were successfully prepared by physical metallurgy techniques and the phase constituents, microstructures, chemical compositions, shape memory effect (SME), and superelasticity (SE) of the Ti–Au–Ta SMAs were also examined. The functionalities, such as SME, were revealed by the introduction of the third element Ta; in addition, obvious improvements of the alloy performances of the ternary Ti–Au–Ta alloys were confirmed while compared with that of the binary Ti–Au alloy. The Ti3Au intermetallic compound was both found crystallographically and metallographically in the Ti–4 at.% Au–30 at.% Ta alloy. The strength of the alloy was promoted by the precipitates of the Ti3Au intermetallic compound. The effects of the Ti3Au precipitates on the mechanical properties, SME, and SE were also investigated in this work. Slight shape recovery was found in the Ti–4 at.% Au–20 at.% Ta alloy during unloading of an externally applied stress.

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