UV light induced plasticization and light activated shape memory of spiropyran doped ethylene-vinyl acetate copolymers

Zhang, Xianzhe; Zhou, Qingqing; Liu, Huarong; Liu, Hewen

doi:10.1039/c4sm00218k

Cited by 65 publications

(36 citation statements)

References 35 publications

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“…with a crystalline phase as the netpoints and a glass transition as the switching phase [103]. Upon UV irradiation at 365 nm, spiropyran molecules isomerize to change from a closed spiro form to an open zwitterionic merocyanine form.…”

Section: Phase Versus Molecular Switches and Thermal Versus Non-thermmentioning

confidence: 99%

Recent progress in shape memory polymer: New behavior, enabling materials, and mechanistic understanding

Zhao

Xie

2015

Progress in Polymer Science

1,191

749

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Shape memory polymers (SMPs), as a class of programmable stimuliresponsive shape changing polymers, are attracting increasing attention from the standpoint of both fundamental research and technological innovations. Following a brief introduction of the conventional shape memory effect (SME), progress in new shape memory enabling mechanisms and triggering methods, variations of in shape memory forms (shape memory surfaces, hydrogels, and microparticles), new shape memory behavior (multi-SME and two-way-SME), and novel fabrication methods are reviewed. Progress in thermomechanical modeling of SMPs is also presented. Abbreviations:SCPs shape changing polymers; LCEs liquid crystalline elastomers; SMP shape memory polymer; SME shape memory effect; 2W two-way; 1W oneway; T trans transition temperature; T g glass transition temperature; T m melting temperature; T cl liquid crystal cleaning temperature; T d deformation temperature; T f shape fixing temperature; T c crystallization temperature; R f shape stability ratio; R r shape recovery ratio; T sw switching temperature; ε max maximum recoverable strain; σ max maximum recovery stress; SMC shape memory cycle; ε load strain under load; ε fixed strain; T r recovery Page 2 of 106 A c c e p t e d M a n u s c r i p t 2 temperature; ε rec recovered strain; V r strain recovery rate; T σmax temperature corresponding to σ max ; T sw,app apparent switching temperature; PCL poly(ε-caprolactone); SMPU shape memory polyurethane; EMU elemental memory unit; TME temperature memory effect; PU polyurethane; T i liquid-crystal isotropic transition temperature; T v vitrification temperature; CIE crystallization induced elongation; MIC melting induced contraction

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Section: Phase Versus Molecular Switches and Thermal Versus Non-thermmentioning

confidence: 99%

Recent progress in shape memory polymer: New behavior, enabling materials, and mechanistic understanding

Zhao

Xie

2015

Progress in Polymer Science

1,191

749

View full text Add to dashboard Cite

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“…Spiropyran (SP) is a well‐known photochromic molecule that can interconvert into a zwitterionic and colored merocyanine (MC) state through a heterolytic ring‐opening reaction induced by external stimuli such as UV‐irradiation, heat, and metal cations . Various photoswitchable derivatives of SPs have been utilized in a wide range of applications including an electro‐mechano‐chemically responsive elastomer, photochromic materials for detection of target proteins, and light‐activated shape memory materials …”

Section: Introductionmentioning

confidence: 99%

Cooperative Binding of Metal Cations to a Spiropyran‐Conjugated Calix[4]arene

et al. 2017

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Cooperative binding occurs frequently in biological systems, but is less exploited in synthetic receptor molecules. We synthesized a bis(spiropyran)‐conjugated calix[4]arene (bSPTC) through a 1,2,3‐triazole linker and found cooperativity in bindings of a series of divalent metal cations (Ca2+, Mg2+, Cd2+, Co2+, Fe2+, Hg2+, Ni2+, and Zn2+). UV‐vis absorption spectroscopy and principle component analysis were used to differentiate the recognized metal cations. The binding stoichiometry was determined by various continuation methods, which indicated that bSPTC has two binding ratios, 1:1 for Zn2+ and 1:2 for all other metal cations. Importantly, positive cooperativity was suggested for the 1:2 stoichiometry of bSPTC to Mg2+ ions from the sigmoidal saturation curve and Hill equation analysis. Density functional theory (DFT) calculations imply that the first binding of Mg2+ to one spiropyran destabilizes the second spiropyran, which facilitates binding of a second Mg2+.

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“…This absorption may occur due to the internal friction between the macromolecules, by shape changes (rotation of the carbon-carbon bonds around its own axis) or by flow. Furthermore, in case of impact, the viscous portion is responsible, for the delay in the elastic response, which will depend on the stimulus and on the time necessary to coil and to uncoil the polymer macromolecule [4,[7][8][9].…”

Section: Viscoelasticitymentioning

confidence: 99%

Systematic study of Ethylene-Vinyl Acetate (EVA) in the manufacturing of protector devices for the orofacial system

Dias

Coto

Batalha

et al. 2017

Archives of Materials Science and Engineering

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Fracture of facial bones and dental elements, and laceration of soft tissue, have increased in sports over recent years. Dentist is the only professional responsible for the mouth protection design, the knowledge about suitable materials is essential. EVA is a thermoplastic material, available in the market, easy of handling and processing, and low-cost. However, it is important to understand the mechanical properties and ability to absorb and to dissipate the impact energy, when this material is submitted to different environments, such as oral cavity with saliva and different temperatures. This chapter show provides a systematic evaluation of the EVA application in orofacial protectors while focusing on sports. The research comprises two aspects: experimental tests and numerical analyses. During experimental tests, EVA was analyzed in special buccal conditions, concerning temperature and presence of saliva. Regarding the presence of saliva, more specific studies about its influence on the mechanical behavior of EVA were performed. In the numerical analyses of the EVA orofacial protector, the studies focused on its effect on the nasal bone integrity, and in the zygomatic bone protection. However, life cycle should be analyzed, since its performance deteriorates over time. Mainly due to the saliva-originated changes to the EVA mechanical characteristics, it can behave as a rigid material. For facial protection, a better performance is obtained with a combination of rigid and soft EVA material. According to the experimental and numerical results from a systematic study of EVA, its application to orofacial protection can be considered satisfactory.

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UV light induced plasticization and light activated shape memory of spiropyran doped ethylene-vinyl acetate copolymers

Cited by 65 publications

References 35 publications

Recent progress in shape memory polymer: New behavior, enabling materials, and mechanistic understanding

Recent progress in shape memory polymer: New behavior, enabling materials, and mechanistic understanding

Cooperative Binding of Metal Cations to a Spiropyran‐Conjugated Calix[4]arene

Systematic study of Ethylene-Vinyl Acetate (EVA) in the manufacturing of protector devices for the orofacial system

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