Macroscopic Regulation of Hierarchical Nanostructures in Liquid-crystalline Block Copolymers towards Functional Materials

Cai, Feng; Chen, Yuxuan; Wang, Wenzhong; Yu, Haifeng

doi:10.1007/s10118-021-2531-1

Cited by 13 publications

(11 citation statements)

References 108 publications

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“…Without the addition of sPEO (0:100, a molar ratio of sPEO to LCBC), PEO-b-PAzo shows PEO nanocylinders with a diameter (d) of 13 nm dispersed hexagonally in the mesogenic continuous phase of the Azo-containing LCP block, as shown in Figures S6 and 2a. 40 As the doping ratio of sPEO increased, the size of cylinders increased correspondingly, which also can be found for the ratios of 10:90 (Figure 2b) and 30:70 (Figure 2c). Further increasing the ratio to 40:60, some deformed cylinders appeared, but in general, the cylinders remained in a hexagonal arrangement (Figure 2d).…”

Section: ■ Results and Discussionsupporting

confidence: 65%

“…As shown in Figure , atomic force microscopy (AFM) phase images reveal that MPS nanostructures of the composite films change significantly at varied doping levels. Without the addition of sPEO (0:100, a molar ratio of sPEO to LCBC), PEO- b -PAzo shows PEO nanocylinders with a diameter ( d ) of 13 nm dispersed hexagonally in the mesogenic continuous phase of the Azo-containing LCP block, as shown in Figures S6 and a . As the doping ratio of sPEO increased, the size of cylinders increased correspondingly, which also can be found for the ratios of 10:90 (Figure b) and 30:70 (Figure c).…”

Section: Results and Discussionmentioning

confidence: 60%

“…Moreover, it is still challenging to trigger heat release at low temperatures, especially below 0 °C . Therefore, using chemical methods to effectively combine PCMs with Azo-containing LCPs shows that nanoscale microphase separation (MPS) can be a promising approach to address these issues. − …”

Section: Introductionmentioning

confidence: 99%

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Enhancement of Solar Thermal Fuel by Microphase Separation and Nanoconfinement of a Block Copolymer

et al. 2021

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Until now, solar thermal energy storage within phase-change materials (PCMs) depends on π–π and van der Waals interactions to improve their miscibility, which often brings about finite enhancement of energy density. Here, we report one nanoconfinement approach to improve energy density using microphase separation of a block copolymer, allowing PCMs to selectively disperse into nanodomains of polymer film for use as solar thermal fuel (STF). Upon doping a certain amount of photoinert organic PCMs with liquid-crystalline block copolymer containing azobenzene as the continuous mesogenic phase, the periodic nanostructures remained due to the microphase separation, which also brings about a distinct nanoconfinement effect for the dopant PCM nanodomains, achieving crystallization temperature from 24 to −38 °C. This unique feature originates from the nanoscale microphase separation, enabling natural sunlight and environmental heat to be stored simultaneously, which can be released in several ways: cis-to-trans isomerization and isotropic-to-liquid crystal phase transition of the azobenzene-containing polymer block at a higher temperature and phase transition of PCMs at a lower temperature, even below −30 °C. Due to the improved STF performance, wearable warm fabrics and photothermal pneumatic actuators were successfully obtained. The present work paves the way for developing high-performance STF systems achieved by microphase separation (MPS) and nanoconfinement, facilitating the advancement and applications of STF materials in the fields of wearable smart materials, warm fabrics, and actuators.

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Section: ■ Results and Discussionsupporting

confidence: 65%

Section: Results and Discussionmentioning

confidence: 60%

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Enhancement of Solar Thermal Fuel by Microphase Separation and Nanoconfinement of a Block Copolymer

et al. 2021

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“…The introduction of photochromic molecules into LCNs yields novel composite materials (such as azo-LCN) that have found various applications where light input is converted into mechanical output [123][124][125][126][127]. Application of azo-LCN as a photodriven polymer oscillator with a frequency as high as a hummingbird wing beat (20-80 Hz) was reported by White et al, where the demonstrated polymer cantilever consisted of a monodomain azobenzene containing LCN [128].…”

Section: Thermoelastic Engines (Artificial Muscles)mentioning

confidence: 99%

Thermomechanical Energy Converters for Harvesting Thermal Energy: A Review

Dimitriev¹

2023

Journal of Renewable Materials

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Thermal energy, i.e., the electromagnetic energy in the infrared range that originates from the direct solar radiation, outgoing terrestrial radiation, waste heat from combustion of fuels, heat-emitting electrical devices, decay of radioactive isotopes, organic putrefaction and fermentation, human body heat, and so on, constitutes a huge energy flux circulating on the earth surface. However, most energy converters designed for the conversion of electromagnetic energy into electricity, such as photovoltaic cells, are mainly focused on using a narrow part of the solar energy lying in the visible spectrum, while thermomechanical engines that are fueled by heat in the broad energy range and then convert it into mechanical work or store it as mechanical deformation, are paid less attention. Although the efficiency of thermomechanical devices is relatively low, they can be applied to collect waste heat which otherwise contributes to negative climate changes. In this review, operational principles of thermomechanical energy converters and a description of basic devices and materials that utilize thermal energy are given. In addition to conventional macroscopic engines, based on thermoacoustic, thermomagnetic, thermoelastic, hydride heat converters, and shape memory alloys, the emergent devices are described which are classified as smart actuators, breathing frameworks, thermoacoustic micro-transducers, nanomechanical resonators, plasmomechanical systems, and optothermal walkers. The performance of the different types of thermomechanical energy converters is described and compared.

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“…[71][72][73] When the mesogenic block serves as the continuous phase in LC block copolymer (LCBC), the orientation of MPS nanostructure can be controlled by tuning the polarization direction of the actinic light. [74] For example, linearly polarized light (LPL) at 488 nm is an effective method to control the orientation of poly(ethylene oxide) (PEO) nanocylinders in an amphiphilic LCBC with PEO as the hydrophilic block and one azobenzenecontaining LCP as the hydrophobic block. [75] Upon annealing without photoirradiation, the PEO nanocylinders were perpendicular to the substrates upon MPS processes, due to the outof-plane orientation of azobenzene mesogens in the smectic LC phase.…”

Section: Photocontrol In Liquid-crystalline Block Copolymermentioning

confidence: 99%

Regulating Surface Topography of Liquid‐Crystalline Polymers by External Stimuli

Yang

Cai

et al. 2022

Macro Chemistry & Physics

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Many polymer materials can respond to external stimuli, so their surface topographies can be regulated in order to achieve specific functions, such as fabrication of lens arrays, control of cell adhesion, and manipulation of object movement. Among them, liquid‐crystalline polymers are the most promising because their unique properties of self‐organization, molecular ordering, and physical anisotropy enable themselves to generate complicated deformation when external stimuli are applied. Here, this work focuses on the principle of topographical deformation of liquid‐crystalline polymers induced by various external stimuli, giving some examples about how to modulate these surface patterns. Accordingly, potential applications of switchable surface topography are presented in the field of photonics, biology, and mechanics. Finally, the existing problems are proposed and future directions in this topic are given an outlook. This review is anticipated to offer new insights and guidelines for developing stimuli‐responsive polymer materials with broader applications.

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Macroscopic Regulation of Hierarchical Nanostructures in Liquid-crystalline Block Copolymers towards Functional Materials

Cited by 13 publications

References 108 publications

Enhancement of Solar Thermal Fuel by Microphase Separation and Nanoconfinement of a Block Copolymer

Enhancement of Solar Thermal Fuel by Microphase Separation and Nanoconfinement of a Block Copolymer

Thermomechanical Energy Converters for Harvesting Thermal Energy: A Review

Regulating Surface Topography of Liquid‐Crystalline Polymers by External Stimuli

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