Toward Stimuli-Responsive Dynamic Thermosets through Continuous Development and Improvements in Covalent Adaptable Networks (CANs)

Covalent adaptable networks (CANs), unlike typical thermosets or other covalently crosslinked networks, possess a unique, often dormant ability to activate one or more forms of stimuli-responsive, dynamic covalent chemistries as a means to transition their behavior from that of a viscoelastic solid to a material with fluid-like plastic flow. Upon application of a stimulus, such as light or other irradiation, temperature, or even a distinct chemical signal, the CAN responds by transforming to a state of temporal plasticity through activation of either reversible addition or reversible bond exchange, either of which allows the material to essentially re-equilibrate to an altered set of conditions that are distinct from those in which the original covalently crosslinked network is formed, often simultaneously enabling a new and distinct shape, function, and characteristics. As such, CANs span the divide between thermosets and thermoplastics, thus offering unprecedented possibilities for innovation in polymer and materials science. Without attempting to comprehensively review the literature, recent developments in CANs are discussed here with an emphasis on the most effective dynamic chemistries that render these materials to be stimuli responsive, enabling features that make CANs more broadly applicable.     

Reprogrammable Assembly of Molecular Motor on Solid Surfaces via Dynamic Bonds

Controllable assembly of molecular motors on solid surfaces is a fundamental issue for providing them to perform physical tasks. However, it can hardly be achieved by most previous methods due to their inherent limitations. Here, a general strategy is designed for the reprogrammable assembly of molecular motors on solid surfaces based on dynamic bonds. In this method, molecular motors with disulfide bonds can be remotely, reversibly, and precisely attached to solid surfaces with disulfide bonds, regardless of their chemical composition and microstructure. More importantly, it not only allows encoding geometric information referring to a pattern of molecular motors, but also enables erasing and re‐encoding of geometric information via hemolytic photocleavage and recombination of disulfide bonds. Thus, solid surfaces can be regarded as “computer hardware”, where molecular motors can be reformatted and reprogramed as geometric information.     

An Adaptable Cryptosystem Enabled by Synergies of Luminogens with Aggregation-Induced-Emission Character

The strong emission in the solid state and the feasibility of introducing stimuli responsiveness make aggregation-induced-emission luminogens promising for optical information encryption. Yet, the vast majority of previous reports rely on subtle changes in the molecular conformation or intermolecular interactions, limiting the robustness, multiplicity, capacity, and security of the resulting cryptosystems. Herein, a versatile cryptographic system is presented based on three interconnected and orthogonal covalent transformations concerning a tetraphenylethylene–maleimide conjugate. The cryptosystem is adapted into four configurations with different functionalities by organizing the reactions and molecules in different ways. These variants either balance the accessibility and security of the encrypted information or improve the security and density in data encryption. Significantly, they allow variable decryption from a single encryption and reconstruction of the chemical nature hidden in the fluorescent pattern can only be accessed through given algorithms. These results highlight the importance of multi-component synergies in advancing information encryption systems, which is enabled by the robustness and diversity stemming from the covalent nature of these transformations.     

Reprogrammable Phononic Metasurfaces

Phononic metamaterials rely on the presence of resonances in a structured medium to control the propagation of elastic waves. Their response depends on the geometry of their fundamental building blocks. A major challenge in metamaterials design is the realization of basic building blocks that can be tuned dynamically. Here, a metamaterial plate is realized that can be dynamically tuned by harnessing geometric and magnetic nonlinearities in the individual unit cells. The proposed tuning mechanism allows a stiffness variability of the individual unit cells and can control the amplitude of transmitted excitation through the plate over three orders of magnitude. The concepts can be extended to metamaterials at different scales, and they can be applied in a broad range of engineering applications, from seismic shielding at low frequency to ultrasonic cloaking at higher frequency ranges.     

Adaptable Hydrogel Networks with Reversible Linkages for Tissue Engineering

Adaptable hydrogels have recently emerged as a promising platform for three‐dimensional (3D) cell encapsulation and culture. In conventional, covalently crosslinked hydrogels, degradation is typically required to allow complex cellular functions to occur, leading to bulk material degradation. In contrast, adaptable hydrogels are formed by reversible crosslinks. Through breaking and re‐formation of the reversible linkages, adaptable hydrogels can be locally modified to permit complex cellular functions while maintaining their long‐term integrity. In addition, these adaptable materials can have biomimetic viscoelastic properties that make them well suited for several biotechnology and medical applications. In this review, an overview of adaptable‐hydrogel design considerations and linkage selections is presented, with a focus on various cell‐compatible crosslinking mechanisms that can be exploited to form adaptable hydrogels for tissue engineering.     

基于产品平台和机械总线的爬行机器人可适应设计

简要介绍了可适应设计的基本思想和原理,并以模块化原理、产品平台为基础,结合机械总线技术进行了可适应爬行机器人实例探索。设计了爬行平台,开发了燕尾槽式总线接口,通过接口的开放扩展性,与两个不同的最终功能执行模块相连接,完成了管外喷涂和管外缠带两个不同的任务,从而实现了基于一个平台对两种不同功能变易的适应性。     

Terpyridine-functionalized surfaces: redox-active, switchable, and electroactive nanoarchitecturesgland

Terpyridines represent versatile functional supramolecular building blocks that are easily integrated in numerous devices and can readily modify surfaces. In particular, redox-active complexes with terpyridine ligands have been attached to surfaces, either by covalent or non-covalent interactions, and form highly ordered mono- or multilayer systems, since electronic and charge transport properties are major topics of interest. Their applications in nanoelectronics are a driving force for understanding and enabling the utilization of the supramolecular properties of terpyridines for surface modification. This area of research has received increasing attention during the last decade leading into the supramacromolecular regime. This Progress Report presents an overview of the state-of-the-art of surface modifications utilizing terpyridine systems and highlights main results, as well as modern trends, in this research area.     

面向定制的液压机可适应产品平台构建方法研究

基于可适应设计理论研究了汽车门盖包边液压机系列产品的可适应产品平台构建方法,构建了包括CAD和CAE模型以及工艺的液压机可适应模块,使用实验设计技术（DOE）分析了模块的各个设计变量对产品性能的贡献值;综合DOE分析结果和单机产品优化结果确定了液压机的公共设计参数和个性设计参数,在产品族优化的基础上构建可适应产品平台,并给出了汽车包边液压机上横梁可适应产品平台构建的实例．