A5034997672- Force Microscopy Techniques and Applications
- Advanced Polymer Synthesis and Characterization
- Polymer crystallization and properties
- Hydrogels: synthesis, properties, applications
- Mechanical and Optical Resonators
- Adhesion, Friction, and Surface Interactions
- Cellular Mechanics and Interactions
- Porphyrin and Phthalocyanine Chemistry
- Polymer Surface Interaction Studies
- Polymer composites and self-healing
- Advanced Sensor and Energy Harvesting Materials
- Advanced Materials and Mechanics
- Supramolecular Self-Assembly in Materials
- Molecular Sensors and Ion Detection
- Dendrimers and Hyperbranched Polymers
- Edible Oils Quality and Analysis
- Analytical Chemistry and Sensors
- Polymer Nanocomposites and Properties
- Photochromic and Fluorescence Chemistry
- Sulfur Compounds in Biology
- Rock Mechanics and Modeling
- Petroleum Processing and Analysis
- Advanced Fluorescence Microscopy Techniques
- Analytical chemistry methods development
- Click Chemistry and Applications
Massachusetts Institute of Technology
2023-2025
Duke University
2019-2024
Chinese Academy of Sciences
2013-2024
Beijing National Laboratory for Molecular Sciences
2021-2024
University of Chinese Academy of Sciences
2024
Southern University of Science and Technology
2017-2018
Southwest Medical University
2016
Institute of Chemistry
2013
Zhaotong University
2008
CAE (Canada)
2008
Longer and stronger; stiff but not brittle Hydrogels are highly water-swollen, cross-linked polymers. Although they can be deformed, tend to weak, methods strengthen or toughen them reduce stretchability. Two papers now report strategies create tough deformable hydrogels (see the Perspective by Bosnjak Silberstein). Wang et al . introduced a toughening mechanism storing releasable extra chain length in part of double-network hydrogel. A high applied force triggered opening cycling strands...
The mechanical properties of covalent polymer networks often arise from the permanent end-linking or cross-linking strands, and molecular linkers that break more easily would likely produce materials require less energy to tear. We report cyclobutane-based mechanophore cross-linkers through force-triggered cycloreversion lead are up nine times as tough conventional analogs. response is attributed a combination long, strong primary strands cross-linker scission forces approximately fivefold...
We present a conceptual framework for adding molecular details of chain extension and force-coupled bond dissociation to the Lake–Thomas model tear energy in rubbery crack propagation. Incorporating data reported from single-molecule force spectroscopy experiments provides an estimate stored per at fracture ∼60 kJ mol–1 typical hydrocarbon polymers, well below carbon–carbon these systems. Opportunities test exploit role covalent scission experimental systems are proposed.
Strain-induced crystallization (SIC) prevalently strengthens, toughens, and enables an elastocaloric effect in elastomers. However, the crystallinity induced by mechanical stretching common elastomers (e.g., natural rubber) is typically below 20%, stretchability plateaus due to trapped entanglements. We report a class of formed end-linking then deswelling star polymers with low defects no entanglements, which achieve strain-induced up 50%. The deswollen end-linked elastomer (DELSE) reaches...
Connecting polymer network fracture to molecular-level chain scission remains a quandary. While the Lake-Thomas model predicts intrinsic energy of is rupture layer chains, it underestimates recent experiments by ∼1-2 orders magnitude. Here we show that polymerlike networks stems from nonlocal dissipation relaxing chains far crack tip using and simulations 2D 3D with varying defects, dispersity, topologies, length scales. Our findings not only provide physical insights into but offer design...
We present a modified Lake–Thomas theory that accounts for the molecular details of network connectivity upon crack propagation in polymer networks. This includes not only energy stored breaking strands (bridging strands) but also tree-like structure connecting bridging to continuum, which remains intact as propagates. The each generations this tree depends nonmonotonically on generation index due nonlinear elasticity stretched strands. Further, required break single strand is necessarily...
Hydrogen fluoride (HF) is a versatile reagent for material transformation, with applications in self-immolative polymers, remodeled siloxanes, and degradable polymers. The responsive situ generation of HF materials therefore holds promise new classes adaptive systems. Here, we report the mechanochemically coupled from alkoxy-gem-difluorocyclopropane (gDFC) mechanophores derived addition difluorocarbene to enol ethers. Production involves an initial assisted rearrangement gDFC mechanophore...
Networks of interconnected materials permeate throughout nature, biology, and technology due to exceptional mechanical performance. Despite the importance failure resistance in network design utility, no existing physical model effectively links strand mechanics connectivity predict bulk fracture. Here, we reveal a scaling law that bridges these levels intrinsic fracture energy diverse stretchable networks. Simulations experiments demonstrate its remarkable applicability breadth constitutive...
Photoresponsive materials that change in response to light have been studied for a range of applications. These are often metastable during irradiation, returning their pre-irradiated state after removal the source. Herein, we report polymer gel comprising poly(ethylene glycol) star polymers linked by Cu
The fracture of rubbery polymer networks involves a series molecular events, beginning with conformational changes along the backbone and culminating chain scission reaction. Here, we report covalent gels in which macroscopic "reaction" is controlled by mechanophores embedded within mechanically active network strands. We synthesized poly(ethylene glycol) (PEG) through end-linking azide-terminated tetra-arm PEG (Mn = 5 kDa) bis-alkyne linkers. Networks were formed under identical conditions,...
Mechanochemical reactions that lead to an increase in polymer contour length have the potential serve as covalent synthetic mimics of mechanical unfolding noncovalent "stored length" domains structural proteins. Here we report force-dependent kinetics stored release a family domain polymers based on cis-1,2-substituted cyclobutane mechanophores. The is determined by size (n) fused ring [n.2.0] bicyclic architecture, and it can be made sufficiently large (>3 nm per event) individual...
In recent decades, more than 100 different mechanophores with a broad range of activation forces have been developed. For various applications in polymer materials, it is crucial to selectively activate the high efficiency, avoiding nonspecific bond scission material. this study, we embedded cyclobutane-based mechanophore cross-linkers (I and II) varied (fa) first network double hydrogels quantitively investigated selectivity efficiency these mechanophores. Our findings revealed that...
Open AccessCCS ChemistryRESEARCH ARTICLE1 Jul 2021Living Bacteria-Mediated Aerobic Photoinduced Radical Polymerization for in Situ Bacterial Encapsulation and Differentiation Huan Lu†, Yiming Huang†, Fengting Lv, Libing Liu, Yuguo Ma Shu Wang Lu† Beijing National Laboratory Molecular Sciences, 100190 Centre the Soft Matter Science Engineering, The Key Lab of Polymer Chemistry & Physics Ministry Education, College Peking University, 100871 , Huang† *Corresponding authors: E-mail Address:...
The fracture of polymer networks is tied to the molecular behavior strands within network, yet specific molecular-level processes that determine mechanical limits a network remain elusive. Here, question reactivity-guided explored in otherwise indistinguishable end-linked by tuning relative composition with two different mechanochemical reactivities. Increasing substitution less mechanochemically reactive ("strong") into comprising more ("weak") has negligible impact on energy until strong...
We present a loop-opening model that accounts for the molecular details of intrinsic fracture energy fracturing polymer networks. This includes not only released from scission bridging chains but also subsequent network continuum. Scission chain releases cross-links and opens corresponding topological loop. The will be caught by opened loop to reach new force-balanced state. amount continuum is limited stretchability Based on this process, we suggest per broken approximately scales with...
Two sensors, 1 with a spirolactone group and 2 spirolactam containing phenyl isothiocyanate moiety, based on rhodol, were designed synthesized in order to obtain materials excellent optical properties for the detection of environmentally biologically important Hg2+ hypochlorous acid (HClO) ions. The crystal structure revealed two moieties, rhodamine-like portion fluorescein-like without spirolactone. In absence analyte, produced an output maximum absorption emission at 475 570 nm,...
Abstract Photoresponsive materials that change in response to light have been studied for a range of applications. These are often metastable during irradiation, returning their pre‐irradiated state after removal the source. Herein, we report polymer gel comprising poly(ethylene glycol) star polymers linked by Cu 24 L metal–organic cages/polyhedra (MOCs) with coumarin ligands. In presence UV light, photosensitizer, and hydrogen donor, this “polyMOC” material can be reversibly switched...
Networks of interconnected materials permeate throughout nature, biology, and technology due to exceptional mechanical performance. Despite the importance failure resistance in network design utility, no existing physical model effectively links strand mechanics connectivity predict bulk fracture. Here, we reveal a universal scaling law that bridges these levels intrinsic fracture energy diverse networks. Simulations experiments demonstrate its remarkable applicability breadth constitutive...
Abstract To endow non‐antibacterial molecules with highly efficient bactericide activity is an important but challenging issue. Herein, a kind of cell‐penetrating peptide octa‐arginine (R8) found to be effective in activating antibacterial ability when assembling anionic surfactant sodium dodecyl sulfate (SDS), while individual R8 or SDS shows poor no ability. By combined electrostatic, hydrogen bond, and hydrophobic interactions, associate into wormlike micelle lamellar structure by forming...
<p>The utility and lifetime of materials made from polymer networks, including hydrogels, depend on their capacity to stretch resist tearing. In gels elastomers, those mechanical properties are often limited by the covalent chemical structure strands between cross-links, which is typically fixed during material synthesis. Here, we report networks in constituent lengthen through force-coupled reactions that triggered as reach nominal breaking point. Reactive strand extensions up 40%...