Wholly Biobased, Highly Stretchable, Hydrophobic, and Self-healing Thermoplastic Elastomer.

Renewable polymers with excellent stretchability and self-healing ability are interesting for a wide range of applications. A novel type of wholly biobased, self-healing, polyamide-based thermoplastic elastomer was synthesized using a fatty dimer acid and a fatty dimer amine, both containing multiple alkyl chains, through facile one-pot condensation polymerization under different polymerization times. The resulting elastomer shows superior stretchability (up to 2286%), high toughness, and excellent shape recovery after being stretched to different strains. This elastomer also displays high room-temperature autonomous self-healing efficiency after fracture and zero water uptake during water immersion. The highly entangled main chain, the multiple dangling chains, the abundant reversible physical bonds, the intermolecular diffusion, and the low ratio of amide to methylene group within the elastomer are responsible for these extraordinary properties. The polymerization time influences the properties of the elastomer. The use of the optimal self-healing thermoplastic elastomer in anticorrosion coating, piezoresistive sensing, and highly stretchable fibers is also demonstrated. The elastomer coating prevents stainless-steel products from corrosion in a salty environment due to its superhydrophobicity. The elastomer serves as a robust flexible substrate for creating self-healing piezoresistive sensors with excellent repeatability and self-healing efficiency. The elastomer fiber yarn can be stretched to 950% of its original length confirming its outstanding stretchability.

Novel Preparation, Microstructure, and Properties of Polyacrylonitrile-Based Carbon Nanofiber-Graphene Nanoplatelet Materials.

Polyacrylonitrile (PAN) fibers containing various concentrations of graphene nanoplatelets (GNPs) were prepared by pressurized gyration, and carbon nanofibers (CNFs) were obtained after subsequent heat treatment and spark plasma sintering (SPS). The influence of processing parameters such as rotational speed, working pressure, carbonization, and SPS temperature on the diameter of the nanofibers has been studied. Furthermore, the thermal properties, morphologies, and crystallization properties of the CNFs have been investigated by using thermogravimetry, scanning and transmission electron microscopy, and Raman spectroscopy. Also, the electrical conductivity and the mechanical properties of these samples have been studied. The results suggest that the gyration conditions and the loading concentration of the GNPs significantly modified the properties of the nanofibers.