Polymer actuators based on covalent adaptable networks

Wu, Yahe; Wei, Yen; Ji, Yan

doi:10.1039/d0py00075b

Cited by 43 publications

(37 citation statements)

References 168 publications

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“…Incorporating DCBs not only provides a means to change the original form of the SMPs but also imparts properties like self-healing, re-processability (reshaping the polymer in its fluidic state), and solid-state plasticity (reshaping polymers permanently without macroscopic melting) while maintaining the mechanical robustness of the materials [ 122 , 123 , 124 ]. Various dynamic covalent chemistries, such as DA cycloadditions [ 37 , 84 , 85 , 86 , 87 ], photoreversible [2+2] cycloadditions [ 58 , 125 ], imine exchange [ 49 ], anhydride exchange [ 83 ], transesterification [ 72 , 77 , 94 , 95 , 96 , 125 ], transcarbamoylation [ 52 , 92 , 93 , 125 ], hindered urea bond exchange [ 92 ], and disulfide exchange [ 42 , 89 , 90 ], have been explored to produce adaptable SMPs.…”

Section: Shape Memory Polymersmentioning

confidence: 99%

“…Various dynamic covalent chemistries, such as DA cycloadditions [37,[84][85][86][87], photoreversible [2+2] cycloadditions [58,125], imine exchange [49], anhydride exchange [83], transesterification [72,77,[94][95][96]125], transcarbamoylation [52,92,93,125], hindered urea bond exchange [92], and disulfide exchange [42,89,90], have been explored to produce adaptable SMPs. Very recently, a comprehensive review about CANs in polymer actuators, such as SMPs and liquid-crystal elastomers (LCEs), has been published by Ji et al [123].…”

Section: Shape Memory Polymersmentioning

confidence: 99%

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Dually Crosslinked Polymer Networks Incorporating Dynamic Covalent Bonds

2021

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Covalent adaptable networks (CANs) are polymeric networks containing covalent crosslinks that are dynamic under specific conditions. In addition to possessing the malleability of thermoplastics and the dimensional stability of thermosets, CANs exhibit a unique combination of physical properties, including adaptability, self-healing, shape-memory, stimuli-responsiveness, and enhanced recyclability. The physical properties and the service conditions (such as temperature, pH, and humidity) of CANs are defined by the nature of their constituent dynamic covalent bonds (DCBs). In response to the increasing demand for more sophisticated and adaptable materials, the scientific community has identified dual dynamic networks (DDNs) as a promising new class of polymeric materials. By combining two (or more) distinct crosslinkers in one system, a material with tailored thermal, rheological, and mechanical properties can be designed. One remarkable ability of DDNs is their capacity to combine dimensional stability, bond dynamicity, and multi-responsiveness. This review aims to give an overview of the advances in the emerging field of DDNs with a special emphasis on their design, structure-property relationships, and applications. This review illustrates how DDNs offer many prospects that single (dynamic) networks cannot provide and highlights the challenges associated with their synthesis and characterization.

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Section: Shape Memory Polymersmentioning

confidence: 99%

Section: Shape Memory Polymersmentioning

confidence: 99%

Dually Crosslinked Polymer Networks Incorporating Dynamic Covalent Bonds

2021

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“…[ 1 ] The research development of the intelligent materials makes the boundary between functional materials and structural materials gradually disappear, which boosts the functionalization and diversification of material structures. At present, a wide variety of the intelligent materials that can change volume, color, conductivity, and shape once responding to specific stimuli have been researched and developed, such as, shape‐memory materials, [ 2‐4 ] liquid crystal elastomer, [ 5,6 ] hydrogels, [ 7,8 ] dielectric elastomer, [ 9 ] piezoelectric materials, [ 10 ] magnetostrictive materials, [ 11 ] and electrochromic materials. [ 12 ]…”

Section: Introductionmentioning

confidence: 99%

The role of branching architecture in shape memory semi‐IPNs: Shape memory effect and tube model analysis

Hou

Zhang

et al. 2021

Polymer Engineering & Sci

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The impact of branching architecture of one continuous uncrosslinked phase on properties of classic shape memory semi‐interpenetrating polymer networks (semi‐IPNs) was explored. Crosslinked poly (methyl methacrylate) (PMMA)/star‐shaped polyethylene glycol (PEG) (PMMA/SPEG) semi‐IPNs and PMMA/linear PEG (PMMA/LPEG) semi‐IPNs were synthesized with the same PEG content. Mechanical properties, phase structure, thermal properties, dynamic mechanical properties, and shape memory properties of these two semi‐IPNs systems were compared. Due to the better compatibility of SPEG in the PMMA network, which was derived from little crystallization compared with PMMA/LPEG semi‐IPNs, PMMA/SPEG semi‐IPNs exhibited a combination of large tensile strength and high elongation at break. PMMA/SPEG semi‐IPNs, which had little crystallization exhibited superior shape recovery versus PMMA/LPEG semi‐IPNs, which had more crystallization. Moreover, the higher the crystallinity in PMMA/PEG semi‐IPNs was the worse long‐term temporary shape retention. Based on tube model theory, the high shape recovery capacity of PMMA/SPEG semi‐IPNs is mainly ascribed to the retraction of free PEG arms, which is entropically favorable and thermally activated due to the fluctuations of the path length. This result is supported by stress relaxation analysis and the influence of long shape fixity time on shape fixity ratio for these two systems.

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“…This “on‐demand” feature has been developed for drug delivery, [ 11 ] ion/gas sensing, [ 12–14 ] self‐assembly, [ 15,16 ] and mechanically actuating systems. [ 17–19 ]…”

Section: Introductionmentioning

confidence: 99%

Photoreversible Loading and Unloading of Q–Silsesquioxane Dynamic Network Sponges

Furgal

2021

Adv Funct Materials

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The synthesis and mechanical properties of photoswitchable silsesquioxane/azobenzene hybrid 3D‐polymers (“dynamic sponges”) are presented and discussed. The hybrid is capable of extensive macroscopic movement, and overcomes previously problematic crosslink locking issues. A hydride‐functionalized Q‐type silsesquioxane (Q8M8H) is reacted with di‐allyloxyazobenzene using hydrosilylation methods. The properties of the resulting materials are controlled via careful choice of starting material ratios and solvent, leading to gels or films. Both morphologies show pronounced photoresponsive behavior in and on the surfaces of different solvents. Photoactuation is tracked by microscopy, dynamic mechanic analysis, and UV–vis spectroscopy. The gel system has a porous structure similar to a sponge. It undergoes shrinkage in volume by 18.3% in toluene under UV irradiation, and shows excellent recovery to the swollen state after irradiation with visible light. These novel photodynamic materials offer reversible modulus switching from 160 kPa in the swollen state to 500 kPa in the “wrung‐out” sponge. The sponges can engage in uptake and release of a range of substances (i.e., reversible hydrophobic sponging), with overall performance determined by solvent specific quantities such as polarity and size. Such behavior gives these materials high potential for soft robotics applications and great promise as reusable environmental remediators.

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Polymer actuators based on covalent adaptable networks

Abstract: Advances in polymer actuators containing covalent adaptable networks (CANs) are summarized and discussed in this review.

Cited by 43 publications

References 168 publications

Dually Crosslinked Polymer Networks Incorporating Dynamic Covalent Bonds

Dually Crosslinked Polymer Networks Incorporating Dynamic Covalent Bonds

The role of branching architecture in shape memory semi‐IPNs: Shape memory effect and tube model analysis

Photoreversible Loading and Unloading of Q–Silsesquioxane Dynamic Network Sponges

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