Scalable Fabrication of High-Performance Bulk Nacre-Mimetic Materials on a Nanogrooved Surface

Lightweight Calcium-Silicate-Hydrate Nacre with High Strength and High Toughness

Low flexural strength and toughness have posed enduring challenges to cementitious materials. As the main hydration product of cement, calcium silicate hydrate (C-S-H) plays important roles in the mechanical performance of cementitious materials while exhibiting random microstructures with pores and defects, which hinder mechanical enhancement. Inspired by the "brick-and-mortar" microstructure of natural nacre, this paper presents a method combining freeze casting, freeze-drying, in situ polymerization, and hot pressing to fabricate C-S-H nacre with high flexural strength, high toughness, and lightweight. Poly(acrylamide-co-acrylic acid) was used to disperse C-S-H and toughen C-S-H building blocks, which function as "bricks", while poly(methyl methacrylate) was impregnated as "mortar". The flexural strength, toughness, and density of C-S-H nacre reached 124 MPa, 5173 kJ/m3, and 0.98 g/cm3, respectively. The flexural strength and toughness of the C-S-H nacre are 18 and 1230 times higher than those of cement paste, respectively, with a 60% reduction in density, outperforming existing cementitious materials and natural nacre. This research establishes the relationship between material composition, fabrication process, microstructure, and mechanical performance, facilitating the design of high-performance C-S-H-based and cement-based composites for scalable engineering applications.

Exploring the Potential of Nonclassical Crystallization Pathways to Advance Cementitious Materials

Understanding the crystallization of cement-binding phases, from basic units to macroscopic structures, can enhance cement performance, reduce clinker use, and lower CO2 emissions in the construction sector. This review examines the crystallization pathways of C-S-H (the main phase in PC cement) and other alternative binding phases, particularly as cement formulations evolve toward increasing SCMs and alternative binders as clinker replacements. We adopt a nonclassical crystallization perspective, which recognizes the existence of critical intermediate steps between ions in solution and the final crystalline phases, such as solute ion associates, dense liquid phases, amorphous intermediates, and nanoparticles. These multistep pathways uncover innovative strategies for controlling the crystallization of binding phases through additive use, potentially leading to highly optimized cement matrices. An outstanding example of additive-controlled crystallization in cementitious materials is the synthetically produced mesocrystalline C-S-H, renowned for its remarkable flexural strength. This highly ordered microstructure, which intercalates soft matter between inorganic and brittle C-S-H, was obtained by controlling the assembly of individual C-S-H subunits. While large-scale production of cementitious materials by a bottom-up self-assembly method is not yet feasible, the fundamental insights into the crystallization mechanism of cement binding phases presented here provide a foundation for developing advanced cement-based materials.

Guidelines derived from biomineralized tissues for design and construction of high-performance biomimetic materials: from weak to strong

Living organisms in nature have undergone continuous evolution over billions of years, resulting in the formation of high-performance fracture-resistant biomineralized tissues such as bones and teeth to fulfill mechanical and biological functions, despite the fact that most inorganic biominerals that constitute biomineralized tissues are weak and brittle. During the long-period evolution process, nature has evolved a number of highly effective and smart strategies to design chemical compositions and structures of biomineralized tissues to enable superior properties and to adapt to surrounding environments. Most biomineralized tissues have hierarchically ordered structures consisting of very small building blocks on the nanometer scale (nanoparticles, nanofibers or nanoflakes) to reduce the inherent weaknesses and brittleness of corresponding inorganic biominerals, to prevent crack initiation and propagation, and to allow high defect tolerance. The bioinspired principles derived from biomineralized tissues are indispensable for designing and constructing high-performance biomimetic materials. In recent years, a large number of high-performance biomimetic materials have been prepared based on these bioinspired principles with a large volume of literature covering this topic. Therefore, a timely and comprehensive review on this hot topic is highly important and contributes to the future development of this rapidly evolving research field. This review article aims to be comprehensive, authoritative, and critical with wide general interest to the science community, summarizing recent advances in revealing the formation processes, composition, and structures of biomineralized tissues, providing in-depth insights into guidelines derived from biomineralized tissues for the design and construction of high-performance biomimetic materials, and discussing recent progress, current research trends, key problems, future main research directions and challenges, and future perspectives in this exciting and rapidly evolving research field.

Desirable Strong and Tough Adhesive Inspired by Dragonfly Wings and Plant Cell Walls

The production of wood-based panels has a significant demand for mechanically strong and flexible biomass adhesives, serving as alternatives to nonrenewable and toxic formaldehyde-based adhesives. Nonetheless, plywood usually exhibits brittle fracture due to the inherent trade-off between rigidity and toughness, and it is susceptible to damage and deformation defects in production applications. Herein, inspired by the microstructure of dragonfly wings and the cross-linking structure of plant cell walls, a soybean meal (SM) adhesive with great strength and toughness was developed. The strategy was combined with a multiple assembly system based on the tannic acid (TA) stripping/modification of molybdenum disulfide (MoS2@TA) hybrids, phenylboronic acid/quaternary ammonium doubly functionalized chitosan (QCP), and SM. Motivated by the microstructure of dragonfly wings, MoS2@TA was tightly bonded with the SM framework through Schiff base and strong hydrogen bonding to dissipate stress energy through crack deflection, bridging, and immobilization. QCP imitated borate chemistry in plant cell walls to optimize interfacial interactions within the adhesive by borate ester bonds, boron-nitrogen coordination bonds, and electrostatic interactions and dissipate energy through sacrificial bonding. The shear strength and fracture toughness of the SM/QCP/MoS2@TA adhesive were 1.58 MPa and 0.87 J, respectively, which were 409.7% and 866.7% higher than those of the pure SM adhesive. In addition, MoS2@TA and QCP gave the adhesive good mildew resistance, durability, weatherability, and fire resistance. This bioinspired design strategy offers a viable and sustainable approach for creating multifunctional strong and tough biobased materials.

Preferential ice growth on grooved surface for crisscross-aligned graphene aerogel with large negative Poisson's ratio

Ice formation on solid surfaces is a ubiquitous process in our daily life, and ice orientation plays a critical role in anti-icing/deicing, organ cryo-preservation, and material fabrication. Although previous studies have shown that surface grooves can regulate the orientation of ice crystals, whether the parallel or perpendicular alignment to the grooves is still under debate. Here, we systematically investigate ice formation and its oriented growth on grooved surfaces through both in situ observation and theoretical simulation, and discover a remarkable size effect of the grooves. With the designability of surface groove patterns, the preferential growth of ice crystals is programmed for the fabrication of a crisscross-aligned graphene aerogel with large negative Poisson's ratio. In addition, the size effect provides guidance for the design and fabrication of solid surfaces where the effective control of ice orientation is highly desired, such as efficient deicing, long time organ cryo-preservation, and ice-templated materials.

Biomimetic Mineralization: From Microscopic to Macroscopic Materials and Their Biomedical Applications

Biomineralization is an attractive pathway to produce mineral-based biomaterials with high performance and hierarchical structures. To date, the biomineralization process and mechanism have been extensively studied, especially for the formation of bone, teeth, and nacre. Inspired by those, abundant biomimetic mineralized materials have been fabricated for biomedical applications. Those bioinspired materials generally exhibit great mechanical properties and biological functions. Nevertheless, substantial gaps remain between biomimetic materials and natural materials, particularly with respect to mechanical properties and mutiscale structures. This Review summarizes the recent progress of micro- and macroscopic biomimetic mineralization from the perspective of materials synthesis and biomedical applications. To begin with, we discuss the progress of biomimetic mineralization at the microscopic level. The mechanical strength, stability, and functionality of the nano- and micromaterials are significantly improved by introducing biominerals, such as DNA nanostructures, nanovaccines, and living cells. Next, numerous biomimetic strategies based on biomineralization at the macroscopic scale are highlighted, including in situ mineralization and bottom-up assembly of mineralized building blocks. Finally, challenges and future perspectives regarding the development of biomimetic mineralization are also presented with the aim of offering insights for the rational design and fabrication of next-generation biomimetic mineralized materials.

Fabricating biomimetic materials with ice-templating for biomedical applications

The proper organization of cells and tissues is essential for their functionalization in living organisms. To create materials that mimic natural structures, researchers have developed techniques such as patterning, templating, and printing. Although these techniques own several advantages, these processes still involve complexity, are time-consuming, and have high cost. To better simulate natural materials with micro/nanostructures that have evolved for millions of years, the use of ice templates has emerged as a promising method for producing biomimetic materials more efficiently. This article explores the historical approaches taken to produce traditional biomimetic structural biomaterials and delves into the principles underlying the ice-template method and their various applications in the creation of biomimetic materials. It also discusses the most recent biomedical uses of biomimetic materials created via ice templates, including porous microcarriers, tissue engineering scaffolds, and smart materials. Finally, the challenges and potential of current ice-template technology are analyzed.

Scalable Manufacturing of Environmentally Stable All-Solid-State Plant Protein-Based Supercapacitors with Optimal Balance of Capacitive Performance and Mechanically Robust

The development of advanced biomaterial with mechanically robust and high energy density is critical for flexible electronics, such as batteries and supercapacitors. Plant proteins are ideal candidates for making flexible electronics due to their renewable and eco-friendly natures. However, due to the weak intermolecular interactions and abundant hydrophilic groups of protein chains, the mechanical properties of protein-based materials, especially in bulk materials, are largely constrained, which hinders their performance in practical applications. Here, a green and scalable method is shown for the fabrication of advanced film biomaterials with high mechanical strength (36.3 MPa), toughness (21.25 MJ m^-3 ), and extraordinary fatigue-resistance (213 000 times) by incorporating tailor-made core-double-shell structured nanoparticles. Subsequently, the film biomaterials combine to construct an ordered, dense bulk material by stacking-up and hot-pressing techniques. Surprisingly, the solid-state supercapacitor based on compacted bulk material shows an ultrahigh energy density of 25.8 Wh kg^-1 , which is much higher than those previously reported advanced materials. Notably, the bulk material also demonstrates long-term cycling stability, which can be maintained under ambient condition or immersed in H₂ SO₄ electrolyte for more than 120 days. Thus, this research improves the competitiveness of protein-based materials for real-world applications such as flexible electronics and solid-state supercapacitors.

Isotropically Ultrahigh Thermal Conductive Polymer Composites by Assembling Anisotropic Boron Nitride Nanosheets into a Biaxially Oriented Network

The demand for thermally conductive but electrically insulating materials has increased greatly in advanced electronic packaging. To this end, polymer-based composites filled with boron nitride (BN) nanosheets have been intensively studied as thermal interface material (TIM). However, it remains a great challenge to achieve isotropically ultrahigh thermal conductivity in BN/polymer composites due to the inherent thermal property anisotropy of BN nanosheets and/or the insufficient construction of the 3D thermal conductive network. Herein, we present a high-performance BN/polymer composite with a biaxially oriented thermal conductive network by a dendritic ice template. The composite exhibits both ultrahigh in-plane (∼39.0 W m^-1 K^-1) and through-plane thermal conductivity (∼11.5 W m^-1 K^-1) at 80 vol % BN loading, largely exceeding those of reported BN/polymer composites. In addition, our composite as a TIM shows higher cooling efficiency than that of commercial TIM with up to 15 °C reduction of the chip temperature and retains good thermal stability even after 1000 heating/cooling cycles. Our strategy represents an effective approach for developing advanced thermal interface materials, which are greatly demanded for advanced electronics and emerging areas like wearable electronics.