Design and synthesis of vertical gradient of expansion structure based on polyimide humidity sensing layer with ultra-fast response, high sensitivity, and large deformation driven by humidity

Jiang, Xueshuang; Chen, Kaijin; Long, Yubo; Chi, Zhenguo; Xu, Jiarui; Zhang, Yi

doi:10.1016/j.cej.2023.143805

Cited by 6 publications

(2 citation statements)

References 57 publications

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“…The diamine and dianhydride monomers were reacted in DMAc for 24 h at room temperature to form viscous poly(amic acid) (PAA) solutions. Since thermal imidization could cause cracking in the films of ODA-HPMDA and FDA-BPDA, the PAA solutions of these two structures, as reported in the previous article, 37 were chemically imidized by adding the catalyst pyridine and the dehydrating agent acetic anhydride, followed by Soxhlet extraction and drying, and then redissolved in DMAc to form viscous polyimide (PI) solutions. Subsequently, the five PAA solutions of DP-BPDA, MDA-BPDA, TPM-BPDA, HMDA-BPDA, and ODA-PMDA and the two PI solutions of ODA-HPMDA and FDA-BPDA were coated on clean glass plates, dried at 80 °C for 1 h, transferred to a nitrogen atmosphere oven, heated at a rate of 2 °C/min to the highest temperature, and kept at the highest temperature for half an hour to obtain seven types of PI films.…”

Section: ■ Introductionmentioning

confidence: 99%

Relationship among the Water Adsorption, Polymer Structure, and High-Frequency Dissipation Factor: Precise Analysis of Water Adsorption of Low-Dielectric Constant Polyimide Films

Bei,

Chen,

Liu

et al. 2024

Macromolecules

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The development of polyimide (PI) films with both a low dielectric constant and low dissipation factor at high frequency is an urgent requirement in a new generation of mobile communication technology. Although some breakthroughs have been made in the study of low-dielectric constant polyimide, the main influencing factors and regulation of the high-frequency dissipation factors are still unclear, which severely limits its development and application, and they deserve further study. In this work, we prepared a series of low-dielectric constant polyimide films and measured their high-frequency dielectric properties at different humidity levels by using a homemade system. The free volume and water adsorption of these polyimide films were precisely evaluated by positron annihilation lifetime spectroscopy and the dynamic vapor sorption method, respectively. Our study shows that the main factor affecting the high-frequency dissipation factor of low-dielectric constant PI films is the water adsorption, and the influence of water adsorption capacity and water binding intensity on the increase of the high-frequency dissipation factor is analyzed in detail. The main factors affecting the water adsorption of these polyimide films are the free volume, molecular polarity index (MPI), and morphology. In the case of a similar structure, imide ring density, and morphology, the free volume of DP-BPDA, MDA-BPDA, TPM-BPDA, and FDA-BPDA gradually increases, resulting in an increase in water adsorption and high-frequency dissipation factors. HMDA-BPDA achieves a low water adsorption of 0.44% due to its appropriate free volume, low MPI, and partial crystallinity, thus achieving good comprehensive performance: low dielectric constant (2.84) and low dissipation factor (0.0029) at 50% RH. Therefore, for polymer materials, designing structures with low polarization, appropriate free volume, and low water adsorption will be an effective strategy to achieve both a low dielectric constant and low dissipation factor.

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Section: ■ Introductionmentioning

confidence: 99%

Relationship among the Water Adsorption, Polymer Structure, and High-Frequency Dissipation Factor: Precise Analysis of Water Adsorption of Low-Dielectric Constant Polyimide Films

Bei,

Chen,

Liu

et al. 2024

Macromolecules

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“…In addition, soft robots can achieve desired applications in a controllable manner without coupling additional instruments, e.g., clamping [8][9][10], crawling [11][12][13], and rolling [14,15]. Currently, the driving structure of soft robots can convert external stimuli, e.g., light [16][17][18], electricity [19,20], magnetism [21], pH [22], temperature [23][24][25], and humidity [26][27][28], into mechanical ene.g., thereby resulting in macroscopic two-dimensional (2D) or three-dimensional (3D) shape changes. Among these external stimuli, light-driven actuation, where light energy can be converted to mechanical ene.g., is considered the best choice to realize small, unconstrained, and bionic stimuli-responsive soft actuators due to some unique properties.…”

Section: Introductionmentioning

confidence: 99%

Light-Responsive Soft Robot Integrating Actuation and Function Based on Laser Cutting

Jia,

Liu,

Zhang

et al. 2024

Micromachines

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Soft robots with good deformability and adaptability have important prospects in the bionics and intelligence field. However, current research into soft robots is primarily limited to the study of actuators and ignores the integrated use of functional devices and actuators. To enrich the functions of soft robots and expand their application fields, it is necessary to integrate various functional electronic devices into soft robots to perform diverse functions during dynamic deformation. Therefore, this paper discusses methods and strategies to manufacture optical stimuli-responsive soft actuators and integrate them into functional devices for soft robots. Specifically, laser cutting allows us to fabricate an optically responsive actuator structure, e.g., the curling direction can be controlled by adjusting the direction of the cutting line. Actuators with different bending curvatures, including nonbending, can be obtained by adjusting the cutting depth, cutting width, and the spacing of the cutting line, which makes it easy to obtain a folded structure. Thus, various actuators with complex shape patterns can be obtained. In addition, we demonstrate a fabrication scheme for a worm-like soft robot integrated with functional devices (LEDs are used in this paper). The local nonbending design provides an asymmetric structure that provides driving power and avoids damage to the functional circuit caused by the large deformation during movement. The integration of drive and function provides a new path for the application of soft robots in the intelligence and bionics field.

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Super‐Flexible Water‐Proof Actuators

Liu,

Yang,

Yan

et al. 2024

Small

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Humidity‐responsive materials hold broad application prospects in sensing, energy production, and other fields. Particularly, humidity‐sensitive, flexibility, and water resistance are pivotal factors in the development of optimized humidity‐responsive materials. In this study, hydrophobic linear polyurethane and hydrophilic 4‐vinylphenylboronic acid (4‐VPBA) form a semi‐intercross cross‐linking network. This copolymer of polyurethane exhibits excellent humidity‐sensitive, mechanical properties, and water resistance. Its maximum tensile strength and maximum elongation can reach 40.56 MPa and 543.47%, respectively. After being immersed in water at various temperatures for 15 days, it exhibited a swelling ratio of only 3.28% in water at 5 °C and 9.58% in water at 70 °C. While the presence of 4‐VPBA network imparts humidity‐sensitive, reversible, and multidirectional bending abilities, under the stimulus of water vapor, it can bend 43° within 1.4 s. The demonstrated material surpasses current bidirectional humidity actuators in actuating ability. Based on these characteristics, automatically opening waterproof umbrellas and windows, as well as bionic‐arms, crawling robots, and self‐propelled boats, are successfully developed.

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Design and synthesis of vertical gradient of expansion structure based on polyimide humidity sensing layer with ultra-fast response, high sensitivity, and large deformation driven by humidity

Cited by 6 publications

References 57 publications

Relationship among the Water Adsorption, Polymer Structure, and High-Frequency Dissipation Factor: Precise Analysis of Water Adsorption of Low-Dielectric Constant Polyimide Films

Relationship among the Water Adsorption, Polymer Structure, and High-Frequency Dissipation Factor: Precise Analysis of Water Adsorption of Low-Dielectric Constant Polyimide Films

Light-Responsive Soft Robot Integrating Actuation and Function Based on Laser Cutting

Super‐Flexible Water‐Proof Actuators

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