4.7 Article

Rheology of Smectic Liquid Crystalline Elastomers with Dynamic Covalent Bonds

Related references

Note: Only part of the references are listed.
Article Chemistry, Multidisciplinary

Fabricating liquid crystal vitrimer actuators far below the normal processing temperature

Yanjin Yao et al.

Summary: Liquid crystal vitrimers with fully covalently cross-linked network structures can undergo topology changes through exchange reactions, allowing for reprocessing, reshaping, welding, and healing. These operations must be performed above a characteristic temperature known as the topology freezing transition temperature (T-v) due to the insignificance of exchange reactions below T-v. However, this study shows that LC vitrimers can be reshaped at temperatures below T-v, unlike non-LC vitrimers. This work not only enables the creation of reprogrammable and stable LC vitrimer actuators at low temperatures but also highlights the need for further attention to measuring and understanding T-v for the use of vitrimers in different areas.

MATERIALS HORIZONS (2023)

Article Chemistry, Multidisciplinary

Robust and Reprocessable Artificial Muscles Based on Liquid Crystal Elastomers with Dynamic Thiourea Bonds

Jin-Hyeong Lee et al.

Summary: This work presents a new class of liquid crystal elastomers that are cross-linked with poly(ether-thiourea) and possess hydrogen bonding capability and dynamic covalent bond exchange at elevated temperatures. These unique properties allow for welding, melt and solution reprocessing, reprogrammable actuation, and self-healing. The LCEs can be used to fabricate electrically powered artificial muscles and biomimetic artificial hands, which demonstrate excellent performance and various hand gestures.

ADVANCED FUNCTIONAL MATERIALS (2022)

Article Polymer Science

Influence of Interfacial Enantiomeric Grafting on Melt Rheology and Crystallization of Polylactide/Cellulose Nanocrystals Composites

Hua-Gao Fang et al.

Summary: Incorporating surface-grafted cellulose nanocrystals (CNCs) with enantiomeric polylactide (PLLA or PDLA) can effectively modify PLLA, with stereocomplexation significantly improving interfacial strength. However, the study found that PLLA/CNC-g-L exhibited a higher crystallization rate compared to PLLA/CNC-g-D, due to its higher nucleation efficiency and faster growth rate. This difference in crystallization behavior was attributed to the presence of a small amount of sc-PLA at the interface in PLLA/CNC-g-L, which restricted PLLA diffusion but contributed less to generating crystalline nuclei.

CHINESE JOURNAL OF POLYMER SCIENCE (2022)

Article Polymer Science

Chemical control of the aromatic disulfide exchange kinetics for tailor-made epoxy vitrimers

Alaitz Ruiz de Rekondo et al.

Summary: Aromatic disulfides containing epoxy vitrimers are versatile materials with potential for industrial applications. This study investigated the effect of different hardener structures, free pending amine groups, and catalysts on the mechanical and dynamic properties of vitrimers. The results showed that the relaxation time and activation energy varied depending on the regioisomerism of the aromatic hardener, stoichiometry, and presence of catalysts. The presence of free pending amine groups or imidazole catalysts reduced the stress relaxation time, making them suitable for processing techniques.

POLYMER (2022)

Article Engineering, Chemical

Endowing Thermally Conductive and Electrically Insulating Epoxy Composites with a Well-Structured Nanofiller Network via Dynamic Transesterification-Participated Interfacial Welding

Fan Zhang et al.

Summary: In this study, the selective distribution of multiwalled carbon nanotubes and hexagonal boron nitride in an epoxy vitrimer matrix was achieved through compression molding, resulting in polymer composites with enhanced thermal conductivity and electrical insulation.

INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH (2022)

Article Polymer Science

Relaxation of Vitrimers with Kinetically Distinct Mixed Dynamic Bonds

Laura Porath et al.

Summary: Designing materials with tunable modulus and viscosity is crucial for various applications. Vitrimers, with their dynamic bond exchange mechanism, provide an ideal platform for viscoelastic design. By using different cross-linkers with varied functionalities and kinetics, control over cross-link density and exchange kinetics can be achieved. Furthermore, combining multiple cross-linkers into a single network allows for a better understanding of the effect of multiple dynamic bonds on the viscoelastic response.

MACROMOLECULES (2022)

Article Polymer Science

Triblock Elastomeric Vitrimers: Preparation, Morphology, Rheology, and Applications

Huagao Fang et al.

Summary: This study introduces the vitrimer chemistry of boronic transesterification into a triblock thermoplastic elastomer, enabling associative bond exchange in its nanoscale domains. The localized dynamic cross-linking improves the material's creep resistance and allows for reprocessing. The study also explores the potential application of the elastomer as a hot-melt adhesive, showing excellent lap shear strength.

MACROMOLECULES (2022)

Article Multidisciplinary Sciences

Rheology of vitrimers

Fanlong Meng et al.

Summary: In this paper, we provide a comprehensive description of the rheological behavior of vitrimers, ranging from small deformation to large deformation. We propose concise analytical expressions to assist in data analysis and clarify emerging insights and concepts in the field. Additionally, we identify the elastic-plastic transition at a timescale comparable to the lifetime of exchangeable bonds in the vitrimer network and propose a new method to deduce material parameters. Furthermore, we investigate partial vitrimers and present a phase diagram of their strain response under different applied loads.

NATURE COMMUNICATIONS (2022)

Article Chemistry, Multidisciplinary

Near-Infrared Light-Driven Shape-Morphing of Programmable Anisotropic Hydrogels Enabled by MXene Nanosheets

Pan Xue et al.

Summary: This study presents a near-infrared light-driven shape-morphing MXene-containing anisotropic hydrogel actuator, which can perform various functions by controlling electrode pattern, electric field direction, and photopolymerization.

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION (2021)

Article Engineering, Multidisciplinary

Vitrimer chemistry enables epoxy nanocomposites with mechanical robustness and integrated conductive segregated structure for high performance electromagnetic interference shielding

Huagao Fang et al.

Summary: Segregated MWCNTs/epoxy composites demonstrate a low conductive percolation threshold at 0.066 wt% and an EMI SE of 22 dB even with only 2 wt% loading of MWCNTs, achieving mechanical robustness and structural integrity.

COMPOSITES PART B-ENGINEERING (2021)

Article Polymer Science

The Crucial Role in Controlling the Dynamic Properties of Polyester-Based Epoxy Vitrimers: The Density of Exchangeable Ester Bonds (ν)

Mao Chen et al.

Summary: Vitrimer materials, which blur the boundary between thermosets and thermoplastics, have dynamic properties that can be influenced by key factors such as the density of exchangeable ester bonds. This control can impact stress relaxation behavior, activation energy, and other intrinsic parameters important for the dynamic properties of vitrimers. Adjusting the density of exchangeable bonds shows promise in designing vitrimer materials for various applications.

MACROMOLECULES (2021)

Article Multidisciplinary Sciences

Impact damping and vibration attenuation in nematic liquid crystal elastomers

Mohand O. Saed et al.

Summary: Nematic liquid crystal elastomers (LCE) exhibit unique mechanical properties such as 'soft elasticity', leading to a wide plateau of low stress upon stretching, slow stress relaxation, and enhanced surface adhesion. The extremely large loss behavior and nearly-constant stress make LCE interesting for damping applications, especially in vibration isolation and impact damping. By optimizing impact and vibration geometries, researchers found good correlation between impact energy dissipation in shaped samples and elastic wave transmission, demonstrating the exceptional damping material properties of nematic LCE.

NATURE COMMUNICATIONS (2021)

Article Polymer Science

Importance of Broad Temperature Windows and Multiple Rheological Approaches for Probing Viscoelasticity and Entropic Elasticity in Vitrimers

Laura E. Porath et al.

Summary: Polydimethylsiloxane telechelic vitrimers with dynamic boronic ester bonds were synthesized to investigate the viscoelastic properties of dynamic networks with extremely low T-g using multiple rheological approaches. Results show that the plateau modulus increases with temperature, while relaxation times decrease, indicating a decoupling of terminal dynamics from mechanics, and a transition from relaxation dominated by reaction exchange kinetics to relaxation dictated by local polymer dynamics. This study highlights the importance of assessing a broad temperature window and using multiple approaches in probing vitrimers and dynamic networks.

MACROMOLECULES (2021)

Article Chemistry, Multidisciplinary

Synergy between dynamic covalent boronic ester and boron-nitrogen coordination: strategy for self-healing polyurethane elastomers at room temperature with unprecedented mechanical properties

Kai Song et al.

Summary: The novel supramolecular polyurethane elastomers (SPUEs) developed in this study achieved mechanical robustness and highly efficient self-healing at room temperature, demonstrating the highest tensile toughness for self-healable polymers and excellent ultimate tensile strength and fracture energy.

MATERIALS HORIZONS (2021)

Article Polymer Science

Catalytic Control of Plastic Flow in Siloxane-Based Liquid Crystalline Elastomer Networks

Mohand O. Saed et al.

ACS MACRO LETTERS (2020)

Article Chemistry, Multidisciplinary

Recycling Epoxy by Vitrimerization: Influence of an Initial Thermoset Chemical Structure

Liang Yue et al.

ACS SUSTAINABLE CHEMISTRY & ENGINEERING (2020)

Article Chemistry, Multidisciplinary

Reprocessable Cross-Linked Polymer Networks: Are Associative Exchange Mechanisms Desirable?

Benjamin R. Elling et al.

ACS CENTRAL SCIENCE (2020)

Article Polymer Science

Rheology of the Critical Transition State of an Epoxy Vitrimer

Huagao Fang et al.

MACROMOLECULES (2020)

Article Agricultural Engineering

Biobased, reprocessable and weldable epoxy vitrimers from epoxidized soybean oil

Yu-Yao Liu et al.

INDUSTRIAL CROPS AND PRODUCTS (2020)

Article Polymer Science

Transesterification in Epoxy-Thiol Exchangeable Liquid Crystalline Elastomers

Alexandra Gablier et al.

MACROMOLECULES (2020)

Article Polymer Science

Influence of the polymer matrix on the viscoelastic behaviour of vitrimers

Yann Spiesschaert et al.

POLYMER CHEMISTRY (2020)

Article Chemistry, Physical

Rates of transesterification in epoxy-thiol vitrimers

Alexandra Gablier et al.

SOFT MATTER (2020)

Review Materials Science, Multidisciplinary

Photomobile Polymer Materials with Complex 3D Deformation, Continuous Motions, Self-Regulation, and Enhanced Processability

Toru Ube et al.

ADVANCED OPTICAL MATERIALS (2019)

Review Chemistry, Multidisciplinary

Adaptable Crosslinks in Polymeric Materials: Resolving the Intersection of Thermoplastics and Thermosets

Georg M. Scheutz et al.

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY (2019)

Article Chemistry, Multidisciplinary

A Light-Powered Ultralight Tensegrity Robot with High Deformability and Load Capacity

Zhijian Wang et al.

ADVANCED MATERIALS (2019)

Article Chemistry, Multidisciplinary

Durable liquid-crystalline vitrimer actuators

Qiaomei Chen et al.

CHEMICAL SCIENCE (2019)

Article Nanoscience & Nanotechnology

Interfacial Engineering for the Synergistic Enhancement of Thermal Conductivity of Discotic Liquid Crystal Composites

Dong-Gue Kang et al.

ACS APPLIED MATERIALS & INTERFACES (2018)

Article Chemistry, Multidisciplinary

Fluorinated Vitrimer Elastomers with a Dual Temperature Response

Marc Guerre et al.

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY (2018)

Review Chemistry, Multidisciplinary

Photothermally driven liquid crystal polymer actuators

Liangliang Dong et al.

MATERIALS CHEMISTRY FRONTIERS (2018)

Article Polymer Science

Tough, Shape-Changing Materials: Crystallized Liquid Crystal Elastomers

Hyun Kim et al.

MACROMOLECULES (2017)

Article Chemistry, Multidisciplinary

Photomobile Liquid-Crystalline Elastomers with Rearrangeable Networks

Toru Ube et al.

ADVANCED MATERIALS (2016)

Article Chemistry, Multidisciplinary

Making and Remaking Dynamic 3D Structures by Shining Light on Flat Liquid Crystalline Vitrimer Films without a Mold

Yang Yang et al.

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY (2016)

Article Polymer Science

Vitrification and plastic flow in transient elastomer networks

Robyn H. Pritchard et al.

POLYMER (2016)

Review Chemistry, Physical

Programmable and adaptive mechanics with liquid crystal polymer networks and elastomers

Timothy J. White et al.

NATURE MATERIALS (2015)

Article Multidisciplinary Sciences

Voxelated liquid crystal elastomers

Taylor H. Ware et al.

SCIENCE (2015)

Article Chemistry, Multidisciplinary

Photomobile Polymer Materials with Crosslinked Liquid-Crystalline Structures: Molecular Design, Fabrication, and Functions

Toru Ube et al.

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION (2014)

Article Chemistry, Physical

Mouldable liquid-crystalline elastomer actuators with exchangeable covalent bonds

Zhiqiang Pei et al.

NATURE MATERIALS (2014)

Article Polymer Science

Catalytic Control of the Vitrimer Glass Transition

Mathieu Capelot et al.

ACS MACRO LETTERS (2012)

Article Multidisciplinary Sciences

Silica-Like Malleable Materials from Permanent Organic Networks

Damien Montarnal et al.

SCIENCE (2011)

Review Chemistry, Multidisciplinary

Liquid Crystalline Elastomers as Actuators and Sensors

Christian Ohm et al.

ADVANCED MATERIALS (2010)

Article Chemistry, Multidisciplinary

Self-assembled shape-memory fibers of triblock liquid-crystal polymers

SV Ahir et al.

ADVANCED FUNCTIONAL MATERIALS (2006)

Article Chemistry, Multidisciplinary

Micro-actuators: When artificial muscles made of nematic liquid crystal elastomers meet soft lithography

A Buguin et al.

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY (2006)

Review Chemistry, Physical

Liquid crystal elastomers, networks and gels: advanced smart materials

P Xie et al.

JOURNAL OF MATERIALS CHEMISTRY (2005)