A Novel Architecture toward Third-Generation Thermoplastic Elastomers by a Grafting Strategy

Thermoplastic elastomers (TPEs) are ever sought using a simple robust synthetic approach. Widely successful first-generation TPEs rely on microphase-separated ABA triblock copolymers (Architecture I). Recent multigraft copolymers represent the second-generation TPEs in which multiple branched rigid segments are dispersed in a rubbery backbone matrix (Architecture II). This paper reports our discovery of the third-generation TPEs that are based on rigid backbone dispersed in a soft grafted matrix. This Architecture III allows the use of random copolymers as side chains to access a wide spectrum of TPEs that cannot be achieved by architecture designs of the first two generations. In this report, random copolymer-grafted cellulose, cellulose-<i>graft</i>-poly­(<i>n</i>-butyl acrylate-<i>co</i>-methyl methacrylate) copolymers with only 0.9–3.4 wt % cellulose prepared by activators regenerated by electron transfer for atom transfer radical polymerization (ARGET ATRP), as novel thermoplastic elastomers are investigated

Robust Amidation Transformation of Plant Oils into Fatty Derivatives for Sustainable Monomers and Polymers

Sustainable fuels, chemicals, and materials from renewable resources have recently gained tremendous momentum in a global scale, although there are numerous nontrivial hurdles for making them more competitive with petroleum counterparts. We demonstrate a robust strategy for the transformation of plant oils into polymerizable monomers and thermoplastic polymer materials. Specifically, triglycerides were converted into <i>N</i>-hydroxyalkyl fatty amides with the aid of amino alcohols via a mild base-catalyzed amidation process with nearly quantitative yields without the use of column chromatography and organic solvents. These fatty amides were further converted into a variety of methacrylate monomers, cyclic norbornene monomers and imino ether monomers. Representative polymers from selected monomers exhibit drastic different physical properties with subtle structural variations, highlighting the potential of this particular amidation reaction in the field of biomass transformation

Bioinspired Design of Nanostructured Elastomers with Cross-Linked Soft Matrix Grafting on the Oriented Rigid Nanofibers To Mimic Mechanical Properties of Human Skin

Human skin exhibits highly nonlinear elastic properties that are essential to its physiological functions. It is soft at low strain but stiff at high strain, thereby protecting internal organs and tissues from mechanical trauma. However, to date, the development of materials to mimic the unique mechanical properties of human skin is still a great challenge. Here we report a bioinspired design of nanostructured elastomers combining two abundant plant-based biopolymers, stiff cellulose and elastic polyisoprene (natural rubber), to mimic the mechanical properties of human skin. The nanostructured elastomers show highly nonlinear mechanical properties closely mimicking that of human skin. Importantly, the mechanical properties of these nanostructured elastomers can be tuned by adjusting cellulose content, providing the opportunity to synthesize materials that mimic the mechanical properties of different types of skins. Given the simplicity, efficiency, and tunability, this design may provide a promising strategy for creating artificial skin for both general mechanical and biomedical applications

Bioinspired High Resilient Elastomers to Mimic Resilin

Natural resilin possesses outstanding mechanical properties, such as high strain, low stiffness, and high resilience, which are difficult to be reproduced in synthetic materials. We designed high resilient elastomers (HREs) with a network structure to mimic natural resilin on the basis of two natural abundant polymers, stiff cellulose and flexible polyisoprene. With plasticization via mineral oil and mechanical cyclic tensile deformation processing, HREs show ultrahigh resilience, high strain, and reasonable tensile strength that closely mimic natural resilin. Moreover, the mechanical properties of HREs can be finely tuned by adjusting the cellulose content, providing the opportunity to synthesize high resilient elastomers that mimic different elastic proteins, such as elastin

Fabrication of Copolymer-Grafted Multiwalled Carbon Nanotube Composite Thermoplastic Elastomers Filled with Unmodified MWCNTs as Additional Nanofillers To Significantly Improve Both Electrical Conductivity and Mechanical Properties

Nanostructured materials have attracted tremendous attention in past decades owning to their wide range of potential applications in many areas. In this study, novel conductive composite thermoplastic elastomers (CTPEs) were fabricated by using a copolymer-grafted multiwalled carbon nanotube (MWCNT) composite thermoplastic elastomer filled with varied amounts of unmodified MWCNTs as additional nanofillers. Rheological measurements and electrical conductivity tests were performed to investigate the viscoelasticity and electrical percolation behavior of these CTPEs, respectively. The incorporation of unmodified MWCNTs can significantly increase the electrical conductivity of these CTPEs, and the electrical conductivity percolation threshold was determined to be 0.34 wt %. The macroscopic mechanical properties of these CTPEs can be conveniently adjusted by the content of unmodified MWCNTs; for example, the strain-hardening behavior can be significantly enhanced with the incorporation of unmodified MWCNTs. This design concept can be generalized to other conductive composite elastomeric systems

Synthesis and Characterization of Nanostructured Copolymer-Grafted Multiwalled Carbon Nanotube Composite Thermoplastic Elastomers toward Unique Morphology and Strongly Enhanced Mechanical Properties

Considering that multiwalled carbon nanotubes (MWCNTs) can be used as anisotropic and stiff nano-objects acting as minority physical cross-linking points dispersed in soft polymer grafting matrixes, a series of copolymer-grafted multiwalled carbon nanotube composite thermoplastic elastomers (CTPEs), MWCNT-<i>graft</i>-poly­(<i>n</i>-butyl acrylate-<i>co</i>-methyl methacrylate) [MWCNT-<i>g</i>-P­(BA-<i>co</i>-MMA)], with minor MWCNT contents of 1.2–3.8 wt % was synthesized by the surface-initiated activators regenerated by electron transfer for atom-transfer radical polymerization (ARGET ATRP) method. Excellent dispersion of the MWCNTs in the CTPEs was demonstrated by SEM and TEM, and the thermal stability properties and glass transition temperatures of the CTPEs were characterized by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), respectively. Mechanical property test results demonstrated that the CTPEs exhibit obviously enhanced mechanical properties, such as higher tensile strength and elastic recovery, as compared with their linear P­(BA-<i>co</i>-MMA) copolymer counterparts. The microstructural evolutions in the CTPEs during tensile deformation as investigated by in situ small-angle X-ray scattering (SAXS) revealed the role of the MWCNTs, which can provide additional cross-linking points and transform soft elastomers into strong ones

Ordering cost with different ordering strategies in Shanghai EMU depot.

<p>Ordering cost with different ordering strategies in Shanghai EMU depot.</p

The PERT chart of EMU overhaul.

<p>The PERT chart of EMU overhaul.</p

Brake discs of CRH2 series EMU.

<p>(A) The axle disc. (B) The wheel disc.</p

Solution framework.

<p>Solution framework.</p