Gels represent an increasingly important class of soft materials with applications ranging from regenerative medicine to commodity materials. However, gels typically exhibit relative mechanical weakness, which worsens under repeated strain. Here we report a new class of responsive gels with latent crosslinking moieties that exhibit strain-stiffening behavior. This property results from the lability of disulfides, initially isolated in a protected state, then activated to crosslink on-demand. The thiol groups are induced to form inter-chain crosslinks when subjected to mechanical compression, resulting in a gel that strengthens under strain. Molecular shielding design elements regulate the strain-sensitivity and spontaneous crosslinking tendencies of the polymer network. These strain-responsive gels represent a rational design of new advanced materials with on-demand stiffening properties and potential applications in elastomers, adhesives, foams, films, and fibers.
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http://dx.doi.org/10.1039/c7sm01888f | DOI Listing |
Analyst
January 2025
Questrom School of Business, Boston University, Boston, MA, 02215, USA.
Latent fingerprints (LFPs) are invisible impressions that need to be developed before being used for criminal investigation; however, existing fingerprint visualization techniques face challenges, such as complex preparation and poor contrast. To advance practical fingerprint detection, green-emissive micron-sized curcumin/kaolin composites were synthesized a facile and cost-effective one-step physical cross-linking method, which exhibited unprecedented performance in developing diversified marks, including LFPs, knuckle prints, palm prints, and footprints, with clear three-level details on various substrates. Notably, the powders successfully developed LFPs that were aged for 30 days and even up to 100 days, meeting the stringent requirements for comprehensive forensic application.
View Article and Find Full Text PDFLangmuir
January 2025
Department of Chemistry, Carnegie Mellon University, 4400 Avenue, Pittsburgh, Pennsylvania 15213, United States.
Structurally tailored and engineered macromolecular (STEM) networks are attractive materials for soft robotics, stretchable electronics, tissue engineering, and 3D printing due to their tunable properties. To date, STEM networks have been synthesized by atom transfer radical polymerization (ATRP) or the combination of reversible addition-fragmentation chain-transfer (RAFT) polymerization and ATRP. RAFT polymerization could have limited selectivity with ATRP inimer sites that can participate in radical-transfer processes.
View Article and Find Full Text PDFACS Appl Mater Interfaces
December 2024
Key Laboratory of Multifunctional and Smart Systems, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China.
Personal thermal protection is crucial in extreme temperature environments, and the rising global temperatures present significant challenges in managing heat stress for individuals. Phase-change materials (PCMs) can absorb or release heat during phase transition to maintain a constant temperature, thus making them ideal innovative thermal protection materials. However, it is currently a bottleneck issue for using PCMs in wearable thermal protection systems due to a balance between the mechanical properties, latent heat, temperature resistance, and rapid response on demand.
View Article and Find Full Text PDFAdv Mater
December 2024
School of Advanced Materials Science and Engineering, Sungkyunkwan University, Seobu-ro 2066, Jangan-gu, Suwon-si, Gyeonggi-do, 16419, Republic of Korea.
Developing a single-component epoxy system is challenging but crucial for advanced thermoset applications. Unfortunately, conventional latent curing agents using chemical or physical passivation do not provide satisfactory storage stability and the necessary property requirements. Here, it is demonstrated that all-in-one epoxy/MXene nanocomposite system, comprising epoxy resin, polymeric imidazole latent curing agent beads (PILCAB), and TiCT MXene, exhibits excellent storage stability, improved flame retardancy, and enhanced mechanical strength.
View Article and Find Full Text PDFMaterials (Basel)
October 2024
Engineering Research Center of Ministry of Education for Geological Carbon Storage and Low Carbon Utilization of Resources, Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing 100083, China.
Personal thermal management materials integrated with phase-change materials have significant potential to satisfy human thermal comfort needs and save energy through the efficient storage and utilization of thermal energy. However, conventional organic phase-change materials in a solid state suffer from rigidity, low thermal conductivity, and leakage, making their application challenging. In this work, polyethylene glycol (PEG) was chosen as the phase-change material to provide the energy storage density, polyethylene oxide (PEO) was chosen to provide the backbone structure of the three-dimensional polymer network and cross-linked with the PEG to provide flexibility, and carbon nanotubes (CNTs) were used to improve the mechanical and thermal conductivity of the material.
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