Selective entanglement coupling of nanoparticles in polymer nanocomposite with high shape recovery stress

Wang, Xiaodong; Jian, Wei; Lu, Haibao; Lau, Denvid; Fu, Yong Qing

doi:10.1016/j.compscitech.2021.108728

Cited by 26 publications

(19 citation statements)

References 45 publications

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“…Recentemente, diversos estudos têm sido conduzidos para obtenção de nanocompósitos poliméricos por meio da combinação de uma matriz polimérica (fase contínua) e uma fase dispersa (não contínua) que tenha pelo menos uma de suas dimensões na escala nanométrica, a qual pode ser zero-dimensional (ex., nanopartículas), 7 unidimensional (ex., nanofibras) 8 e bidimensional (ex., nanoplaquetas). 9,10 Tais materiais são facilmente processáveis e podem exibir propriedades mecânicas, elétricas, óticas, dentre outras, melhoradas quando comparados aos compósitos em que a fase dispersa é formada por macroestruturas.…”

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Nanocompósitos Poliméricos

Martins¹,

Migliorini²,

Teodoro³

et al. 2022

Nanotecnologia Aplicada a Polímeros

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A busca por materiais com propriedades otimizadas para aplicações em áreas diversas como engenharia, medicina, indústria automobilística e aeroespacial tem levado à utilização em larga escala de materiais compósitos. Esses são produzidos pela combinação de dois ou mais materiais com propriedades físicas e/ou químicas distintas entre si, resultando em um material final multifásico com características intermediárias das fases constituintes e desempenho final superior, devido à combinação otimizada de propriedades. [1][2][3] Os materiais compósitos podem ser baseados em matrizes poliméricas (compósitos poliméricos), 4 matrizes cerâmicas (compósitos cerâmicos) 5 ou ainda matrizes metálicas (compósitos metálicos). 6 Dentre esses, os compósitos poliméricos são amplamente utilizados em diversas aplicações, pois os polímeros, atuando como matriz, oferecem vantagens sobre outros materiais, proporcionando propriedades otimizadas. 3,4

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unclassified

Nanocompósitos Poliméricos

Martins¹,

Migliorini²,

Teodoro³

et al. 2022

Nanotecnologia Aplicada a Polímeros

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“…In semi-crystalline polymer, four types of conformational entropies should be considered [Lee et al, 2010]: disorientation entropy (Sd), confinement entropy (Sce), interfacial entropy (Si) and mixing entropy (Smix). Meanwhile, confinement entropy (Sce) and interfacial entropy (Si) both are used to restrict the relaxation of amorphous phase, while the mixing entropy (Smix) is able to promote the relaxation [Lee et al, 2010;Wang et al, 2021],…”

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confidence: 99%

“…where φa and φc are the volume fractions of amorphous and crystalline phases, respectively. ra and rc are the molar volume ratios of amorphous and crystalline phases, respectively [Wang et al, 2021]. Rc and r0 are the radii of the crystalline phase and semi-crystalline chain, respectively [Ginzburg, 2005].…”

mentioning

confidence: 99%

“…The parameters used in equation ( 12) are A0=5, m=3.6, Fa=8000 J/mol, s *. Δ μ =3020 J/mol [Macedo et al, 1965], Rc/r0=0.9 [Wang et al, 2021], γ=γi=0.75 [Wang et al, 2021], z=4 [Treloar, 2005] and εpre,a=10% [Luo et al, 2010]. It is revealed that the phase transitions of amorphous phase are completed at 322.9 K, 331.4 K, 334.5 K and 336.1 K, with the volume fraction of crystalline phase (φc) increased from 5%, 10%, 15% to 20%, respectively.…”

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confidence: 99%

“…Values of parameters used in equation ( 12) during calculation are listed in Table 1, where s *. Δ μ =5950J/mol [Macedo et al, 1965], ra/rc=1.1×10 5 , Rc/r0=0.9, γ=γi=0.75 [Wang et al, 2021] and z=4 [Treloar, 2005]. As shown in Fig.…”

mentioning

confidence: 99%

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Interfacial Confinement in Semi-Crystalline Shape Memory Polymer Towards Sequentially Dynamic Relaxations

Liu

Xing

et al. 2021

Int. J. Appl. Mechanics

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Sequential glass and melting transitions in semi-crystalline shape memory polymers (SMPs) provide great opportunities to design and generate multiple shape-memory effects (SMEs) for practical applications. However, the complexly dynamic confinements of coexisting amorphous and crystalline phases within the semi-crystalline SMPs are yet fully understood. In this study, an interfacial confinement model is formulated to describe dynamic relaxation and shape memory behavior in the semi-crystalline SMPs undergoing sequential phase/state transitions. A confinement entropy model is first established to describe the glass transition behavior of amorphous phase within the SMPs based on the free volume theory, where the free volume is critically confined by the crystalline phase. An extended Avrami model is then formulated using the frozen volume theory to characterize the melting and crystallization transitions of the crystalline phase in the SMPs, whose interfacial confinement with the amorphous phase has been identified as the driving force for the supercooled regime. Furthermore, an extended Maxwell model is formulated to describe the effect of dynamic confinement of two phases on the multiple SMEs and shape recovery behaviors in the semi-crystalline SMPs. Finally, the effectiveness of the newly proposed model is verified using the experimental data reported in the literature. This study aims to provide a new methodology for the dynamic confinements and cooperative principles in the semi-crystalline SMP towards multiple SMEs.

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Water‐Assisted Reprocessing and Shape Programming of Epoxy Vitrimer

Xu,

Zhou,

Fang

et al. 2024

Adv Funct Materials

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Vitrimers are reprocessing and recycling thermosetting plastics. They possess reconfigurable polymer networks that allow for unlimited transformation in shape in principle. However, current strategies to reshape the vitrimers typically involve heat or light, which often induces undesirable oxidation and decomposition. To address this issue, here a water‐assisted approach is proposed for programming epoxy vitrimers’ shapes. In this design, water molecules are utilized to reversibly dissociate the hydrogen bonds in epoxy vitrimers to enable the polymer segments to move flexibly. The hydrated epoxy vitrimers can then be reprogrammed and retained into different temporary shapes by removing the water. Such samples would be recovered to their original shapes by rehydration, exhibiting water‐induced shape memory property. More than temporary deformation, the permanent figures of the hydrated vitrimers can also be permanently changed at room temperature (rt) or elevated temperatures in the presence of transesterification catalysts. Combing the shape memory and high temperature plasticity or utilizing rt plasticity, sophisticated shapes such as spiral shapes are demonstrated. It is envisioned that this water‐assisted methodology can be useful in programming cross‐linked polymers into diverse 3D structures, which has wide practical applications in soft robots, deployable devices, aerospace materials, etc.

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Selective entanglement coupling of nanoparticles in polymer nanocomposite with high shape recovery stress

Cited by 26 publications

References 45 publications

Nanocompósitos Poliméricos

Nanocompósitos Poliméricos

Interfacial Confinement in Semi-Crystalline Shape Memory Polymer Towards Sequentially Dynamic Relaxations

Water‐Assisted Reprocessing and Shape Programming of Epoxy Vitrimer

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