Yijie Hu,Hao Zhuo,Zehong Chen,Xinwen Peng,Linxin Zhong,Runcang Sun
Interfacial design is one of the most promising ways in improving mechanical properties of nanocomposites . In this work, a multifunctional aerogel with excellent mechanical performances, sensing sensitivity, and fire retardancy is fabricated by taking advantage of metal coordination between biopolymer and Fe 3+ . Montmorillonite (MMT) nanosheets are added to induce a ‘brick and mortar’ structure. The coordination remarkably reduces structural defects , leading to well-formed lamellas that can effectively distribute stress under sever compression without plastic deformation . The structural merits impart the aerogel highly reversible compressibility even at 99 % strain and superior durability. Besides, it demonstrates high sensing performance in wearable health monitoring devices, and shows fire resistance property that can maintain elasticity in a flame. The work offers a facile and effective method to create multifunctional aerogels from various polymers.
It is a challenging work to design novel responsive materials by controlling the secondary structure of polypeptide , especially β-sheet. We designed and synthesized a novel dual responsive diblock copolymer of methyl poly (ethylene glycol)- b -poly (O-benzyl- l -threonine) (mPEG- b -PBnLT). The copolymer solutions exhibited unusual and reversible gel-to-sol-to-gel transition behavior with temperature, and the transition temperature window could be easily adjusted by changing copolymer concentration or PBnLT block length . It was confirmed that low temperature gel-to-sol transition was due to the disassembly of the preliminary β-sheet layered nano-assemblies that induced the transformation of self-organized morphology from nanosized fibrils to spherical aggregates, while the high temperature sol-to-gel transition was ascribed to the dehydration of PEG segments. The disassembly of β-sheet structures was caused by the change in the polarity of the pendant benzyl ether bond of PBnLT block in water with temperature. This stimuli-responsiveness of secondary self-assembled nanostructures and the corresponding change in macroscopic phase transition inspires a brand-new strategy for structural design and functional control of polypeptide materials.
Glycerol plasticized soy protein is an important kind of biodegradable materials among the possible soy protein systems. Fully realized performance relies on the investigation and understanding of the molecular structure of the plasticized soy protein. However, the relevant research is primarily limited in the microstructure and physical properties of the mixtures with a lack of knowledge on the intermolecular interactions at molecular and nano-scale levels. In this work, intermolecular interaction and molecular motion of soy protein in glycerol plasticized systems were investigated at molecular and nanometer levels. Several techniques including atomic force microscope (AFM), transmission electron microscope (TEM) and 13 C solid-state nuclear magnetic resonance ( 13 C NMR), have been effectively employed. Observations from AFM and TEM indicated that the glycerol plasticized soy protein materials were heterogeneous at nanometer scale and there were two important phases existing in the materials, i.e. protein-rich domain and glycerol-rich domain. The protein-rich domain was composed of compact aggregations of pan-like protein while the glycerol-rich domain possessed a loose chain-like structure. Further studies on the interactions between soy protein and glycerol at molecular level using NMR indicated that the strong hydrogen bonds between glycerol and protein molecules was greatly affected by amino acid residues on protein chains. The protein-rich micro-domains were mainly composed of amino acids with long alkane lateral chains or aromatic ring lateral groups, while amino acids with polar groups or short nonpolar lateral groups formed glycerol-rich micro-domains. These results would be beneficial for the development and realization of plasticized soy protein based nanocomposites and blend materials with high performance.
危险品化学品经营许可证（带存储）