Non-equilibrium Nanoassemblies Constructed by Confined Coordination on a Polymer Chain

Design and applications of antifreeze polysaccharide-based hydrogels for cryoprotection and biotechnological advancements: A review

Polysaccharide-based hydrogels possess desirable characteristics such as flexibility, biocompatibility, and biodegradability. Nevertheless, these hydrogels frequently lose their inherent traits and functionality under low-temperature circumstances, which significantly restricts their potential applications in cold environments. Antifreeze hydrogels provide a promising solution to this challenge by maintaining their properties at cold temperatures, showcasing remarkable advantages. This review commences with a bibliometric analysis via VOS Viewer to acquire a comprehensive comprehension of the development tendencies in antifreeze hydrogels. It subsequently summarizes diverse antifreeze mechanisms in polysaccharide-based hydrogels, encompassing solute ion modification, organic alcohol modification, ion gels, eutectic gels, and intrinsic antifreeze properties through molecular chain polymerization. Additionally, the review explores the applications of antifreeze hydrogels in food preservation, flexible wearable devices, and energy storage. Finally, the future directions for the development of antifreeze polysaccharide-based hydrogels are deliberated, with an emphasis on the utilization of natural polysaccharide resources to create hydrogels that integrate antifreeze performance, mechanical properties, and stability, thereby facilitating advancements in related industries.

Construction of Luminescent Terpyridine-Based Metallo-Bowties with Alkyl Chain-Bridged Dimerized Building Blocks

Numerous metallo-supramolecules with well-defined sizes and shapes have been successfully constructed via the strong coordination interaction between terpyridine (TPY) moieties and ruthenium cations. However, the pseudo-octahedral geometry of unit hampers the luminescent properties of such metallo-architectures, thus limiting their applications as optical materials. To address this issue, we herein use a flexible alkyl chain to bridge TPY building blocks, replacing conventional linkage. The introduction of alkyl chain guides the self-assembly into desired architecture while simultaneously eliminating the quenching effects typically associated with the linkage. More importantly, this design strategy enables the precise construction of bowtie-shaped metallo-supramolecules with significantly enhanced emission. The incorporation of alkyl chain linkage not only maintains structural integrity but also enhances optical performance, making these metallo-supramolecular assemblies highly promising for applications in advanced photonic and luminescent materials. This study offers a versatile approach to construct complex metallo-supramolecular architectures with desired optical properties.

Single-Nanoparticle Electrochemical Collision for Monitoring Self-Assembly of Thiol Molecules on Au Nanoparticles

A precise understanding of the self-assembly kinetics of small molecules on nanoparticles (NPs) can give greater control over the size and architecture of the functionalized NPs. Herein, a single-nanoparticle electrochemical collision (SNEC)-based method was developed to monitor the self-assembly processes of 6-mercapto-1-hexanol (6-MCH) and 1-hexanethiol (MCH) on Au NPs at the single-particle level, and to investigate the self-assembly kinetics exactly. Results showed that the self-assembly processes of both consisted of rapid adsorption and slow recombination. However, the adsorption rate of MCH was significantly lower than that of 6-MCH due to the poorer polarity. Also noteworthy is that the rapid adsorption of 6-MCH on Au NPs conformed to the Langmuir model of diffusion control. Hence, the proposed SNEC-based method could serve as a complementary method to research the self-assembly mechanism of functionalized NPs.

Kinetically Controlled and Nonequilibrium Assembly of Block Copolymers in Solution

Covalent polymers are versatile macromolecules that have found widespread use in society. Contemporary methods of polymerization have made it possible to construct sequence polymers, including block copolymers, with high precision. Such copolymers assemble in solution when the blocks have differing solubilities. This produces nano- and microparticles of various shapes and sizes. While it is straightforward to draw an analogy between such amphiphilic block copolymers and phospholipids, these two classes of molecules show quite different assembly characteristics. In particular, block copolymers often assemble under kinetic control, thus producing nonequilibrium structures. This leads to a rich variety of behaviors being observed in block copolymer assembly, such as pathway dependence (e.g., thermal history), nonergodicity and responsiveness. The dynamics of polymer assemblies can be readily controlled using changes in environmental conditions and/or integrating functional groups situated on polymers with external chemical reactions. This perspective highlights that kinetic control is both pervasive and a useful attribute in the mechanics of block copolymer assembly. Recent examples are highlighted in order to show that toggling between static and dynamic behavior can be used to generate, manipulate and dismantle nonequilibrium states. New methods to control the kinetics of block copolymer assembly will provide endless unanticipated applications in materials science, biomimicry and medicine.

Highly robust supramolecular polymer networks crosslinked by a tiny amount of metallacycles

Supramolecular polymeric materials have exhibited attractive features such as self-healing, reversibility, and stimuli-responsiveness. However, on account of the weak bonding nature of most noncovalent interactions, it remains a great challenge to construct supramolecular polymeric materials with high robustness. Moreover, high usage of supramolecular units is usually necessary to promote the formation of robust supramolecular polymeric materials, which restrains their applications. Herein, we describe the construction of highly robust supramolecular polymer networks by using only a tiny amount of metallacycles as the supramolecular crosslinkers. A norbornene ring-opening metathesis copolymer with a 120° dipyridine ligand is prepared and self-assembled with a 60° or 120° Pt(II) acceptor to fabricate the metallacycle-crosslinked polymer networks. With only 0.28 mol% or less pendant dipyridine units to form the metallacycle crosslinkers, the mechanical properties of the polymers are significantly enhanced. The tensile strengths, Young's moduli, and toughness of the reinforced polymers reach up to more than 20 MPa, 600 MPa, and 150 MJ/m3, respectively. Controllable destruction and reconstruction of the metallacycle-crosslinked polymer networks are further demonstrated by the sequential addition of tetrabutylammonium bromide and silver triflate, indicative of good stimuli-responsiveness of the networks. These remarkable performances are attributed to the thermodynamically stable, but dynamic metallacycle-based supramolecular coordination complexes that offer strong linkages with good adaptive characteristics.