Multifunctional liquid metal polymer composites

Liquid metal polymer composites are an emerging class of functional materials with potentially transformative impacts in wearable electronics, soft robotics, and human-computer interactions. By employing different processing methods, room temperature liquid metal inclusions can be embedded in insulating polymers like elastomers to incorporate functional properties of metals while the matrix remains soft and stretchable. These solid–liquid composites offer an interesting, yet complex multifunctional material system. In this review, we present an exclusive overview of the synthesis methods, structural and functional properties, and applications of gallium-based liquid metal polymer composites. Common methods to control the size of liquid metal inclusions and their interaction in polymers are discussed. Moreover, the effect of liquid metal microstructures on the overall properties of the composites is summarized. We also highlight the new trends in terms of material composition, printing process, and novel applications of liquid metal polymer composites in intelligent systems.     

滨海软土地层机械法联络通道施工影响监测分析

机械法联络通道T接施工技术是一种施工软土地区地铁联络通道的新型工法, 具有全程机械化、施工周期短、可直接切削主隧道和洞口等优点. 以宁波地铁3号线某联络通道工程为研究对象, 通过监测分析研究新工法对周围地层、主隧道结构等的施工影响. 结果表明: 受交叉施工影响, 联络通道纵向靠近主隧道的地表沉降较大, 靠近联络通道中央影响较小; 横向中心位置地表沉降较大, 两侧影响较小; 主隧道结构沉降及隧道断面收敛变形较小; 顶推过程对周围地层影响明显, 但水平地面受影响较小, 表明地层总体沉降量小, 基本可控. 此外, 采用peck曲线和高斯曲线分别描述纵横向地面沉降的变化特征, 采用回归分析确定了沉降曲线参数, 与实际监测结果相比, 两者拟合良好.     

Liquid Crystal Soft Actuators and Robots toward Mixed Reality

Liquid crystals (LCs) are soft but smart materials that can adjust its chemical or physical properties in response to various external stimuli. Using these materials to construct soft actuators and robots, referred as LC actuators and robots, is expected to replace current machinery part, obtaining lighter and smaller equipment with adjustable and complex functions. Especially, combining these LC actuator and robots with existing virtual reality and augmented reality technologies will produce a new world of mixed reality (MR) with the visual, auditory, and somatosensory interaction. In this review, the recent work on responsive LC actuators and robots is introduced, emphasizing on their potentials in haptic use. By discussing their programmable control via suitable stimuli, the LC actuators and robots are summarized for mechanical outputs, environmental mimic, and fine-tuning of surface texture and roughness. It is anticipated that the continuous development on LC actuators and robots will accelerate the MR technology toward practical application.     

Microstructured Actuation of Liquid Crystal Polymer Networks

Smart microstructured materials enable functions such as actuation, detection, transportation, and sensing with potential applications ranging from robotics and photonics to biomedical devices. Of the many materials systems, liquid crystal polymer networks (LCN) are fascinating owing to their ability to exhibit reversible macroscopic deformation driven by a molecular order–disorder phase transition. LCN have been increasingly explored for their utility in the design and fabrication of smart actuating devices capable of complex shape changes or motions upon external stimulation of humidity, heat, light, and other stimuli, and recent studies in this field show that their actuation complexity can be enriched and actuation performance enhanced by having some sort of microstructures. Herein, the recent progress in microstructured actuation of LCN materials with substructures in scale ranging from micrometer to millimeter is reported, placing the emphasis on the main approaches to generating a microstructure in LCN, which include patterned LC director fields, patterned chain crosslinking in LCN with uniaxial orientation of mesogens, 3D/4D printing, and replica molding. The potential applications in microstructured 3D actuators and devices as well as functional LCN surfaces are also highlighted, with an outlook on important issues and future trends in smart microstructured LCN materials and actuators.     

Liquid‐Crystalline Soft Actuators with Switchable Thermal Reprogrammability

Thermal reprogrammability is essential for new‐generation large dry soft actuators, but the realization sacrifices the favored actuation performance. The contradiction between thermal reprogrammability and stability hampers efforts to design high‐performance soft actuators to be robust and thermally adaptable. Now, a strategy has been developed that relies on repeatedly switching on/off thermal reprogrammability in liquid‐crystalline elastomer (LCE) actuators to resolve this problem. By post‐synthesis swelling, a latent siloxane exchange reaction can be induced in the common siloxane LCEs (switching on), enabling reprogramming into on‐demand 3D‐shaped actuators; by switching off the dynamic network by heating, actuation stability is guaranteed even at high temperature (180 °C). Using partially black‐ink‐patterned LCEs, selectively switching off reprogrammability allows integration of completely different actuation modes in one monolithic actuator for more delicate and elaborate tasks.