Physical and thermo-mechanical properties of shape memory polyurethane containing reversible chemical cross-links

Mehrbakhsh, Elaheh; Rezaei, Mehran; Babaie, Amin; Mohammadi, Amir; Sofla, Reza Lotfi Mayan

doi:10.1016/j.jmbbm.2021.104336

Cited by 18 publications

(14 citation statements)

References 61 publications

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“…In other samples, it was found that after incubation in a buffer solution some of the hydrogen bonds between the ester and urethane groups had dissociated and the bands corresponding to the C=O free groups became more clearly visible (Figure 5). The presence in this region of the spectrum of bands corresponding to the vibrations of free C=O groups and bounded by hydrogen bonds was indicated by other authors [40,41].…”

Section: Chemical Structuresupporting

confidence: 65%

Degradability of Polyurethanes and Their Blends with Polylactide, Chitosan and Starch

et al. 2021

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One of the methods of making traditional polymers more environmentally friendly is to modify them with natural materials or their biodegradable, synthetic equivalents. It was assumed that blends with polylactide (PLA), polysaccharides: chitosan (Ch) and starch (St) of branched polyurethane (PUR) based on synthetic poly([R,S]-3-hydroxybutyrate) (R,S-PHB) would degrade faster in the processes of hydrolysis and oxidation than pure PUR. For the sake of simplicity in the publication, all three modifiers: commercial PLA, Ch created by chemical modification of chitin and St are called bioadditives. The samples were incubated in a hydrolytic and oxidizing environment for 36 weeks and 11 weeks, respectively. The degradation process was assessed by observation of the chemical structure as well as the change in the mass of the samples, their molecular weight, surface morphology and thermal properties. It was found that the PUR samples with the highest amount of R,S-PHB and the lowest amount of polycaprolactone triol (PCLtriol) were degraded the most. Moreover, blending with St had the greatest impact on the susceptibility to degradation of PUR. However, the rate of weight loss of the samples was low, and after 36 weeks of incubation in the hydrolytic solution, it did not exceed 7% by weight. The weight loss of Ch and PLA blends was even smaller. However, a significant reduction in molecular weight, changes in morphology and changes in thermal properties indicated that the degradation of the samples should occur quickly after this time. Therefore, when using these polyurethanes and their blends, it should be taken into account that they should decompose slowly in their initial life. In summary, this process can be modified by changing the amount of R,S-PHB, the degree of cross-linking, and the type and amount of second blend component added (bioadditives).

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Section: Chemical Structuresupporting

confidence: 65%

Degradability of Polyurethanes and Their Blends with Polylactide, Chitosan and Starch

et al. 2021

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“…Crystallization of PCL chains is highly limited in PU structure due to the restrictions applied by the anchoring of hard segments and also mixing of the hard segments in the soft phases. [34] Therefore, degree of crystallinity of PCL chains is reduced from 68% to 40% in the PU structure. However, addition of the neat MNPs increased this value about 5% because of its higher DPS than PU.…”

Section: Chemical Characteristicsmentioning

confidence: 99%

“…Crystallization ability of the PCL soft segments in the PU and its nanocomposites cause these samples to show shape memory behavior. [34] Therefore, their shape memory behavior was studied using typical stress-strain curves at room temperature and 50 °C to evaluate their shape memory properties, including shape fixity and shape recovery ratios. According to Figure 7, it is deduced that the shape memory potential of samples is higher when they are initially stretched at 50 °C.…”

Section: Shape Memory Behaviormentioning

confidence: 99%

“…At this circumstance, recrystallization of the PCL crystals during cooling step alongside the applied stress direction leads them to preserve higher content of the temporary shape. [13,34] However, lack of orientation of preformed crystals alongside the stress direction for the samples stretched at room temperature have prevented them to fix all the applied temporary shape. [34] However, the shape fixity ratios of samples, initially deformed at room temperature, depict a decreasing trend with their degrees of crystallinity, which is because of the fact that the presence of crystals restricts PU chains to retain their highest entropy level and as consequently fix their temporary shapes.…”

Section: Shape Memory Behaviormentioning

confidence: 99%

“…[13,34] However, lack of orientation of preformed crystals alongside the stress direction for the samples stretched at room temperature have prevented them to fix all the applied temporary shape. [34] However, the shape fixity ratios of samples, initially deformed at room temperature, depict a decreasing trend with their degrees of crystallinity, which is because of the fact that the presence of crystals restricts PU chains to retain their highest entropy level and as consequently fix their temporary shapes. Moreover, the permeant deformation during the shape recovery step is due to the high content of hard segments.…”

Section: Shape Memory Behaviormentioning

confidence: 99%

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Tuning Microphase Separation, Thermal Characteristics, and Physicomechanical Properties of Shape Memory Polyurethanes by Incorporation of Isocyanate‐Modified Fe₃O₄ Magnetic Nanoparticles

Babaie

Rezaei

Roghani‐Mamaqani

2021

Macro Materials & Eng

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Fe 3 O 4 magnetic nanoparticles (MNPs) are subsequently modified with (3-aminopropyl) triethoxysilane (APTES) and octadecyl isocyanate (OD) to yield MNPs-g-OD. Fourier-transform infrared (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM) verified successful modification of MNPs with three different ratios of OD. Shape memory polyurethane (SMPU) nanocomposites containing 4 wt% of the neat, APTES-grafted, and OD-grafted MNPs are prepared through solution casting, where a strong correlation is achieved between the microstructure, crystallinity, thermal, and mechanical properties of the nanocomposites. Phase mixing degree of the soft and hard phases is increased by hydrogen bonding between the OD and polyurethane (PU) chains, causing to decrease of crystallization ability of PU chains. Field-emission scanning electron microscopy (FE-SEM) images show that high dispersion of MNPs-g-OD reduces the number and size of their aggregation sites in the PU matrix. The nanocomposites show high Young's modulus, because of increasing hydrogen bonding index of carbonyl groups with incorporation of MNPs-g-OD into the PU matrix. The nanocomposites show lower Young's modulus with increasing the degree of crystallinity. Shape memory studies indicated that all the samples have considerable shape memory abilities at 50 °C and room temperature. However, shape fixity ratios show a close dependence on the degree of crystallinity at room temperature.

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Synthesis of dual‐stimuli‐responsive polyurethane shape memory nanocomposites incorporating isocyanate‐functionalized Fe₃O₄ nanoparticles

Babaie

Rezaei

Razzaghi

et al. 2022

J of Applied Polymer Sci

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Thermally and magnetically stimulated shape memory polyurethane (PU) nanocomposites were synthesized for intravascular stent applications.For this end, Fe 3 O 4 magnetic nanoparticles (MNPs) were modified with octadecyl isocyanate (OD) to increase their affinity with the PU matrix by formation of the covalent urea linkages. The results showed that the OD-grafted MNPs were replaced instead of carbonyl groups of polycaprolactone (PCL) soft segments in hydrogen bond formation with the urethane linkages. This led to higher phase separation degrees among the soft and hard phases, thereby PCL chains could reveal higher crystallization potential. Mechanical studies showed that the nanocomposites had high mechanical strength, Young's modulus, and elongation at break, which improve their practical applications. The nanocomposites showed thermo-responsive shape memory behavior with a high shape recovery and shape fixity ratios due to the presence of the crystallizable PCL segments. The nanocomposite containing 10 wt% of the OD-grafted MNPs could recover its original shape (during 90s) in a relatively weak alternating magnetic field (350 kHz and 12.9 kA/m). These results indicated that the prepared nanocomposites could be used to normalize the narrowed blood vessels through the remotely and magnetically-controllable restricted shape recovery process.

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Physical and thermo-mechanical properties of shape memory polyurethane containing reversible chemical cross-links

Cited by 18 publications

References 61 publications

Degradability of Polyurethanes and Their Blends with Polylactide, Chitosan and Starch

Degradability of Polyurethanes and Their Blends with Polylactide, Chitosan and Starch

Tuning Microphase Separation, Thermal Characteristics, and Physicomechanical Properties of Shape Memory Polyurethanes by Incorporation of Isocyanate‐Modified Fe₃O₄ Magnetic Nanoparticles

Synthesis of dual‐stimuli‐responsive polyurethane shape memory nanocomposites incorporating isocyanate‐functionalized Fe₃O₄ nanoparticles

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Physical and thermo-mechanical properties of shape memory polyurethane containing reversible chemical cross-links

Cited by 18 publications

References 61 publications

Degradability of Polyurethanes and Their Blends with Polylactide, Chitosan and Starch

Degradability of Polyurethanes and Their Blends with Polylactide, Chitosan and Starch

Tuning Microphase Separation, Thermal Characteristics, and Physicomechanical Properties of Shape Memory Polyurethanes by Incorporation of Isocyanate‐Modified Fe3O4 Magnetic Nanoparticles

Synthesis of dual‐stimuli‐responsive polyurethane shape memory nanocomposites incorporating isocyanate‐functionalized Fe3O4 nanoparticles

Contact Info

Product

Resources

About

Tuning Microphase Separation, Thermal Characteristics, and Physicomechanical Properties of Shape Memory Polyurethanes by Incorporation of Isocyanate‐Modified Fe₃O₄ Magnetic Nanoparticles

Synthesis of dual‐stimuli‐responsive polyurethane shape memory nanocomposites incorporating isocyanate‐functionalized Fe₃O₄ nanoparticles