Design of mechanically robust self-healing elastomers based on tung oil-derived dangling chains
In order to optimize the mechanical properties and repair ability of self-healing materials,this study focused on how to design and prepare new elastomers with high strength and rapid self-healing performance using natural and renewable forestry biomass raw materials.To this end,a series of thermoplastic polyurethane elastomers containing suspended chains and dynamic covalent bonds were constructed using woody oil-based tung oil as a raw material,and reactive functional monomer(TOD)through the efficient ammonolysis reaction as a"soft segment".By utilizing the self-healing properties of conjugated double bonds in the side chains of TOD fatty acids,the self-conjugated double bonds in the side chains of fatty acids were further exploited to form multiple cross-linked structures by simple thermal processing to obtain robust self-healing materials.The chemical structure of TOD monomer was determined by the 1H nuclear magnetic resonance(1HNMR),Fourier transform infrared(FT-IR)measurements,and its effective chemical cross-linking after thermal processing was confirmed,thus contributing to the enhancement of the mechanical properties of the system,with tensile strength up to 16.16 MPa and strain at break of 1 318％.Analysis of the thermo-mechanical properties of the elastomers showed that the introduction of a small amount of TOD would significantly in-crease the glass transition temperature(Tg)of polyurethanes containing dynamic disulfide bonds,ultimately achieving efficient healing of the polyurethanes in a room temperature environment while ensuring stable mechanical properties of the materials.The healing efficiency(with the stress as a reference)of the as-prepared films can be as high as 95.4％after 24 h of healing at room temperature,while the elastic recovery rate reaches 94.4％.The results showed that the asymmetric structure of the tung oil-derived dangling chain could break the regularity of the molecular chain,which in turn induced a more rapid metathesis of the disulfide bond at room temperature and contributed to the self-healing of the material.Owing to the presence of dynamic bond structure in the system,the obtained cross-linked elas-tomer exhibited stable re-processability at moderate temperature.It was verified that the mechanical properties of the elastomers remained consistent with the original values after several physical recycling and did not show any significant decrease.It is believed that this work opens new ideas for the high-value utilization of woody oils and is expected to enrich the theoretical system of high-performance elastomers.It was indicated that the oil-based functional polyurethane elastomers have a broad application prospect.
国家科技期刊平台
NSTL
万方数据
维普
