Bio‐Inspired Semi‐Active Safeguarding Design with Enhanced Impact Resistance via Shape Memory Effect

Abstract

Inspired by creatures reducing impact damage, a novel semi-active protection strategy to enhance impact resistance through structural adjustment is proposed. The heat-activated shape memory composites (PCLE) consisting of polycaprolactone (PCL) and shear stiffening elastomer are first prepared. The PCLE with 50 wt.% PCL (PCLE-50%) presents tensile strength of 0.46 MPa, fracture strain of 148%, high shape fixity and recovery rates (97.9% and 91.1%), and stable shape-memory repeatability. Furthermore, various PCLE-50%-based structures are fabricated, which show reinforced anti-impact performance after shape-shifting. Loading from 300 mm, the maximum drop hammer impact force of no protection, PCLE-50%, and deformed assembled single-branch structure are 3.98 kN, 1.75 kN, and 0.93 kN, respectively. Additionally, assembled complex structures also exhibit exceptional energy absorption properties. Ultimately, intelligent clothing is successfully manufactured. Besides good anti-impact effect, the clothing shows excellent thermal insulation capabilities whose surface temperature is 31.7 °C after heating for 600 s at 42 °C. This study provides an innovative means to develop deformable, wearable, and intelligent protective devices.

Bitumen‐Like Polymers Prepared via Inverse Vulcanization with Shear Stiffening and Self‐Healing Abilities for Multifunctional Applications

“…All these phenomena indicate the existence of shear stiffening performance. [50][51][52][53][54][55] We performed rheological tests to quantitatively characterize this solid-liquid transition behavior. As shown in Figure 3C, the storage modulus of Sul 2 -Sor 3 -Eug 5 is only 10 2 Pa in the low-frequency region, showing a completely viscous behavior.…”

Entropy-Driven Design of Highly Impact-Stiffening Supramolecular Polymer Networks with Salt-Bridge Hydrogen Bonds

“…To address this challenge, impact-stiffening materials have been developed as smart soft armors, retaining softness under quasi-static conditions while undergoing dramatic stiffening upon impact at high strain rates . Two notable examples include polyborosiloxanes (PBSs) or Silly Putty, which rely on rate-dependent B–O dative bonds, and shear-thickening fluids (e.g., cornstarch and silica suspensions), which operate based on a reentrant jamming transition. , To enhance their functionality, numerous efforts have focused on modifying their composition or hybridizing them with fillers/scaffolds. − Nevertheless, constrained by material type and rate-responsive mechanisms, the stiffening response of current impact-stiffening materials remains relatively low, with the storage modulus ( G ′) increase generally less than 1000 times within the typical shear frequency range of 0.1–100 Hz.…”

Intelligent anti-impact elastomers by precisely tailoring the topology of modular polymer networks

“…Elastomers are extensively used in diverse industrial sectors (e.g., tyres, conduits, and cables), [1][2][3] and have attracted increasing attention in emerging fields (e.g., wearable protection, flexible displays, and soft robotics). [4][5][6] Unlike traditional rigid materials such as ceramics, steels, and plastics, elastomers with good portability and high flexibility are perfect for preparing well-fitted protective armors or coatings, enhancing security in domains of personal and industrial protection. 7,8 Currently, the concept of elastomers has broadened to include traditional elastomers such as vulcanized rubber and silicone, as well as newly developed segmented copolymers like polyurethanes and polyurea.…”