On the Size Effect of Additives in Amorphous Shape Memory Polymers

Zirdehi, Elias M.; Dumlu, Hakan; Eggeler, Gunther; Varnik, Fathollah

doi:10.3390/ma14020327

Cited by 6 publications

(5 citation statements)

References 78 publications

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“…They attributed the shape recovery to the entropy changes rather than the internal energy. Having applied a shape memory cycle on various polymers, other researchers [30,31] reported similar outcomes. In another MD-based study, Yang et al [32] examined the effect of different percentages of curing agent on the shape memory characteristics of epoxy polymer substrate.…”

Section: Introductionmentioning

confidence: 76%

“…Prior to the shape memory studies, the models went through a process to attain their equilibrated state. To this aim, the process began with a minimization step using conjugate gradient, which was then followed by a five-cycled annealing process (The details have been described in [30].). After removing the residual stress, the density of the fully equilibrated pristine polymer model was obtained as 1.23 g mol −1 .…”

Section: Computational Detailsmentioning

confidence: 99%

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Engineering the shape memory parameters of graphene/polymer nanocomposites through atomistic simulations: On the effect of nanofiller surface treatment

Amini¹,

Hasheminejad²,

Montazeri³

2021

Smart Mater. Struct.

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This paper aims to comprehend the mechanisms underlying the shape memory behavior of polylactic acid infused with graphene functionalized by four groups of -OH, -CH3, -NH2, and tethered polymer layer. Applying molecular dynamics simulation, it is revealed that the graphene surface treatment enhances the shape fixity ratio of nanocomposites monotonically by increasing the physical cross-linking points within the polymer matrix. The improvement would be even more pronounced by increasing the coverage degree of small functional groups and grafting density of the covalently bonded polymer chains. Monitoring the key parameters illustrates that contrary to the OH groups, which improve the shape recovery value, the other functional groups degrade it by prohibiting the polymer chains mobility. Attempts to explore the governing mechanism demonstrate that shape fixity is improved when the difference between the potential energy variations in the loading and unloading stages increases. Interestingly, shape recovery is only under the influence of conformational entropy, and it is not affected by the potential energy. As such, we also probe variations of the radius of gyration during the recovery stage to address the role of different functionalization procedures on the reported shape recovery parameter.

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Section: Introductionmentioning

confidence: 76%

Section: Computational Detailsmentioning

confidence: 99%

Engineering the shape memory parameters of graphene/polymer nanocomposites through atomistic simulations: On the effect of nanofiller surface treatment

Amini¹,

Hasheminejad²,

Montazeri³

2021

Smart Mater. Struct.

View full text Add to dashboard Cite

show abstract

“…diffusion in polymers [1,2] is combined with shape memory polymer (SMP) technology [3,4]. In previous work, the chemical actuation of the shape memory effect was studied [5][6][7][8]. Chemical actuation was triggered by the diffusion of small molecules into a SMP.…”

Section: Background and Scientific Objectivesmentioning

confidence: 99%

Diffusion of small-size aliphatic alcohols and the chemical actuation of shape memory polyurethane

Shen,

Dumlu,

Varnik

et al. 2024

Smart Mater. Struct.

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Three types of aliphatic alcohols (methanol, ethanol, and 1-propanol) are used to actuate a programmed ESTANE ETE 75DT3 (abb. SMP-E), a polyether-based polyurethane shape memory polymer (SMP). In this paper, we analyze the diffusion behavior of these small molecules in SMP E and the relationship between the solvent diffusion and shape recovery using a weight gain study and small-angle x-ray scattering (SAXS). From the results, all three alcohols show behavior similar to Fickian diffusion in SMP-E. During the diffusion process, the molecular switch of thermoplastic SMP-E transforms from the glassy state to the rubber like state depending on the time-dependent local alcohol concentration. The diffusion of small molecules enhances shape recovery and the related evolution of the polymer structure. As a feedback effect, the rate of diffusion changes as small molecules penetrate into the sample. To study this issue, we used three methods to determine the diffusion coefficients at short, intermediate and long times. The data on short time diffusion reflects the glassy state of the sample. The intermediate times correspond to 50% solvent saturation, where the shape recovery is nearly completed. The long-time analysis, on the other hand, provides an average diffusion coefficient for the entire process. The SAXS results show the diffusion path and provide evidence that the alcohol molecules equally diffuse into both molecular switch (MS) and entropy elastic component (EE) phase of SMP E.

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“…SMPs find extensive applications in diverse fields including biomedicine, aerospace, textiles, protective equipment, and so on . Furthermore, research has extended into the field of four-dimensional (4D) printing materials, involving the use of biocompatible polycaprolactone softeners to enhance the shape memory effects and FFF printability of poly(vinyl chloride), as well as studies on the applications of polycaprolactone-thermoplastic polyurethane composites. − The most prevalent SMPs among these are heat-triggered SMPs (HSMPs). − The temporary shapes of HSMPs tend to be generated at temperatures higher than the transition temperature ( T trans , glass transition temperature ( T g ) or melting temperature ( T m )), which provides structural flexibility to the chain segments. Shape memory effects (SME) are commonly observed in various block copolymers, where the hard segments possess physical or chemical cross-linked points while the soft segments assume permanent and temporary shapes, respectively.…”

Section: Introductionmentioning

confidence: 99%

Biobased and Biodegradable Shape Memory Polymers of Eucommia Ulmoides Gum and Polycaprolactone via Dynamic Vulcanization

Kang,

Cui,

et al. 2024

Ind. Eng. Chem. Res.

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On the Size Effect of Additives in Amorphous Shape Memory Polymers

Cited by 6 publications

References 78 publications

Engineering the shape memory parameters of graphene/polymer nanocomposites through atomistic simulations: On the effect of nanofiller surface treatment

Engineering the shape memory parameters of graphene/polymer nanocomposites through atomistic simulations: On the effect of nanofiller surface treatment

Diffusion of small-size aliphatic alcohols and the chemical actuation of shape memory polyurethane

Biobased and Biodegradable Shape Memory Polymers of Eucommia Ulmoides Gum and Polycaprolactone via Dynamic Vulcanization

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