Takahiro Matsuda

Living tissues, such as muscle, autonomously grow and remodel themselves to adapt to their surrounding mechanical environment through metabolic processes. By contrast, typical synthetic materials cannot grow and reconstruct their structures once formed. We propose a strategy for developing "self-growing" polymeric materials that respond to repetitive mechanical stress through an effective mechanochemical transduction. Robust double-network hydrogels provided with a sustained monomer supply under

Double network (DN) gels, consisting of a brittle first and flexible second network, have been known to be extremely tough and functional hydrogels. In a DN gel subjected to force, the brittle first network breaks prior to the fracture of the flexible network. This process, referred to as internal fracture, dissipates energy and increases the energy required to completely fracture DN gels. Such internal fracture macroscopically appears as a yielding-like phenomenon. The aim of this paper is to i

The double-network (DN) structure is a state-of-the-art strategy used for toughening soft materials. The challenge for widespread applications, however, is the difficulty in synthesizing the two interpenetrating networks with contrasting architecture, i.e., one network is brittle and sparse and the other is stretchable and dense. Such structures are formed to toughen hydrogels via two-step sequential synthesis of a highly swellable polyelectrolyte network and a subsequent stretchable network in

Quantitative characterization of the energy dissipation zone around a crack tip is the focal point in the fracture mechanics of soft materials. In this report, we present a mechanochemical technique for the visualization and quantification of the degree of polymer strand scission in the damage zone of tough double-network hydrogels. This technique uses mechanoradicals generated by covalent bond scission to initiate radical polymerization, which records the internal fracturing around the crack ti

The high fracture energy of tough soft materials can be attributed to the large energy dissipation zone around the crack tip. Hence, quantitative characterization of energy dissipation is the key to soft matter fracture mechanics. In this study, we quantified the energy dissipation in the damage zone of a double-network (DN) hydrogel using a mechanochemical technique based on mechanoradical polymerization combined with confocal fluorescence microscopy. We found that, in addition to energy dissip

• Current-assisted sinter bonding enables reliable SiC–Ag joints at low temperatures. • Enhanced bonding mitigates interfacial fractures, effectively strengthening sinter joints. • Ag ion migration densifies interfaces by facilitating Ag precipitation on SiC surfaces. • Minimal Ag 2 O ensures effective bonding via current-driven ion migration in sintered layers. Sinter bonding using fine metal particles has attracted significant attention as a promising technology for next-generation power devic

Mechanical yielding of double-network (DN) hydrogels is a distinctive feature of classical polymer networks, which links to toughening of the DN gels. Previous studies have focused on the effect of swelling on the yield point; however, yield strain and yield stress could not be decoupled from each other, which restricted the solid understanding of the micromechanical model of the yielding. In this study, we investigated the yield point of various DN gels where the first-network parameters (prepa

Quantitative characterization of the energy dissipative zone around the crack tip is the central issue in fracture mechanics of soft materials. In this research, we present a mechanochemical technique to visualize the bond scission of the first network in the damage zone of tough double-network hydrogels. The mechanoradicals generated by polymer chain scission are employed to initiate polymerization of a thermoresponsive polymer, which is visualized by a fluorophore. This technique records the s

In reinforced concrete flexural members, premature shear failure, which is brittle and occurs suddenly, must be avoided, if maximum flexural bearing capacity in critical areas is to be attained. Steel fibers have been found to enhance the performance of RC beams through stress redistribution after cracking and by transforming the brittle failure to a ductile mode. In this regard and for purposes of development of design guidelines, prediction of the strength and deformation capacity is fundament

Quantitative characterization of the energy dissipative zone around the crack tip is the central issue in fracture mechanics of soft materials. In this research, we present a mechanochemical technique to visualize the bond scission of the first network in the damage zone of tough double-network hydrogels. The mechanoradicals generated by polymer chain scission are employed to initiate polymerization of a thermoresponsive polymer, which is visualized by a fluorophore. This technique records the s

• Fracture path tailored by bilayer structuring with graded deformability. • Pre-sintering temperature controls dislocation density and Ag layer bondability. • Graded microstructures mitigate interfacial fracture via stress redistribution. • Nanoindentation evidences elastic modulus gradients enabling stress relaxation. • Graded deformability design applicable to diverse dissimilar material joints. Ensuring the mechanical reliability of Ag sinter-bonded joints remains a critical challenge in pow