Fiber‐Reinforced Viscoelastomers Show Extraordinary Crack Resistance That Exceeds Metals

Abstract

Soft fiber‐reinforced polymers (FRPs), consisting of rubbery matrices and rigid fabrics, are widely utilized in industry because they possess high specific strength in tension while allowing flexural deformation under bending or twisting. Nevertheless, existing soft FRPs are relatively weak against crack propagation due to interfacial delamination, which substantially increases their risk of failure during use. In this work, a class of soft FRPs that possess high specific strength while simultaneously showing extraordinary crack resistance are developed. The strategy is to synthesize tough viscoelastic matrices from acrylate monomers in the presence of woven fabrics, which generates soft composites with a strong interface and interlocking structure. Such composites exhibit fracture energy, Γ, of up to 2500 kJ m−2, exceeding the toughest existing materials. Experimental elucidation shows that the fracture energy obeys a simple relation, Γ = W · lT, where W is the volume‐weighted average of work of extension at fracture of the two components and lT is the force transfer length that scales with the square root of fiber/matrix modulus ratio. Superior Γ is achieved through a combination of extraordinarily large lT (10–100 mm), resulting from the extremely high fiber/matrix modulus ratios (104–105), and the maximized energy dissipation density, W. The elucidated quantitative relationship provides guidance toward the design of extremely tough soft composites.

Healable, Recyclable, and Mechanically Tough Polyurethane Elastomers with Exceptional Damage Tolerance

“…[35] To the best of our knowledge, the PU-BPY 0.5 -Zn elastomers have the highest fracture energy among all the reported elastomers. [9,36,38,46] Moreover, the fracture energy of our elastomers is much higher than that of Zn alloys and Ti alloys ( Figure S7, Supporting Information). [9,36,38,46] Following the same method, the fracture energies of PU-BPY 0 and PU-BPY 0.5 were measured to be 30.9 ± 0.2 and 78.4 ± 1.4 kJ m −2 , respectively, indicating that coordination interactions between the bipyridine groups and Zn 2+ ions are important for enhancing the damage tolerance of the PU-BPY 0.5 -Zn elastomers.…”

“…The damage tolerance of elastomers or other kinds of polymer materials requires efficiently dissipating energy concentrated in the damaged regions. [9,38,39] Damage-tolerant polymer composites with high mechanical strength can be fabricated by embedding stiffer fibers or particles within relatively soft matrices. [9,36,38] Damagetolerant elastomers with fracture energies ranging from several tens to a maximum value of ≈120 kJ m −2 have been fabricated.…”

“…[9,38,39] Damage-tolerant polymer composites with high mechanical strength can be fabricated by embedding stiffer fibers or particles within relatively soft matrices. [9,36,38] Damagetolerant elastomers with fracture energies ranging from several tens to a maximum value of ≈120 kJ m −2 have been fabricated. [9] There is a huge requirement of elastomers for use in tires, seals, and shock absorbers every year worldwide.…”

Printable homocomposite hydrogels with synergistically reinforced molecular-colloidal networks

“…The hierarchically branched SDCs are expected to serve as efficient reinforcement in composite materials. Their branches provide large surface area, which could increase the composite stability by distributing the stress more uniformly 41,[45][46][47][48][49] . We investigate here the SDC effectiveness in reinforcing homocomposite hydrogels, expecting that the high surface area and maximized adhesivity between the SDC network and the matrix will result in hydrogels of outstanding mechanical properties.…”

Ultrarobust, tough and highly stretchable self-healing materials based on cartilage-inspired noncovalent assembly nanostructure

“…The side chains of proteoglycan molecules in cartilage matrix are connected with collagen fibers through hydrogen bonds to form a network structure, and a large number of collagen fibers are interwoven into a network which can bear the force. Previously, a number of studies have combined woven fiber networks or hard plastic skeletons with soft matrix to achieve ultrahigh mechanical properties of composites [35][36][37][38] . This undoubtedly proves the effectiveness of the cartilage-like structure strategy of assembling a rigid "skeleton" into a flexible matrix by strong adhesion.…”