Studies On The Preparation And Performance Of Self-healing Elastomers Based On Oxime-urethane Bond

Self-healing material is a novel material,which can repair the damaged part after being damaged,so that the performance of the material can be restored,the life of the material can be prolonged,and the guarantee of green sustainable chemistry can be provided.However,how to obtain high self-healing and high mechanical strength at the same time requires us to construct the interaction based on hydrogen bond and dynamic oxime carbamate bond from the molecular perspective and the phase regulation of hard segment,explore the regulation of different types of soft or hard segment phase in the system,and balance the mechanical properties and self-healing properties of materials.Based on it,polyurethane elastomers based on two different dynamic bonds were synthesized in this paper,and the materials were endowed with different properties through phase regulation.(1)Synthesis and performance of PU elastomers based on hydrogen bonds.Reasonable design of the balance between the hard segment content regulating mechanical properties and self-healing properties is a strategy for the synthesis of self-healing polyurethane elastomers.Therefore,we synthesized three kinds of self-healing polyurethane with different molecular weights of poly(propylene oxide diol)(PPG)and isophorone diisocyanate(IPDI)as prepolymers,which selected different steric hindrance of citric acid(CA)or 2,6-pyridine dimethanol(PDM)as chain extenders.The results of Fourier transform infrared spectroscopy(FTIR)and tensile tests indicate that there is dynamic hydrogen bond interaction in the system and the effect of different hard segment content and steric resistance on hydrogen bond interaction,which endows the elastomer with unique mechanical properties and self-healing properties.The tensile strength of PPG1000-CA elastomer is 2.15 ± 0.07 MPa,the elongation of chain break is 1181 ± 15%,and it has proper self-healing(reaching 72.9± 0.2%at 80 ? 24 h).In the bonding test,the bonding strength of PPG1000-CA elastomer on aluminum substrate is 1.06 MPa,which provides a simple and novel idea for practical durable protective coatings and other fields.(2)Synthesis and study of high toughness and high efficiency self-healing PU elastomer based on oxime carbamate bond.Acquiring simultaneous high strength and toughness,and efficient self-healability of polyurethane(PU)elastomer is of great challenge due to their exclusive dependence on hard segments.Herein,a transparent,punctureresistant,notch-insensitive,resilient and self-healable elastomer(PDO-IP2.5)with giant tensile strength(29.5±0.9 MPa),excellent toughness(124.9 ± 2.2 MJ/m3),outstanding fracture energy(83.9 kJ/m2),high puncture energy(625 mJ)and balanced self-healing efficiencies(SEs calculated in tensile strength,elongation at break and toughness>95%)and fast physical wound re-mending(?60 s upon hot airflow)is successfully developed through deliberate phase regulation,i.e.rational design of asymmetric and bulky hard segments and optimization of hard segments content.The resulting loosely-packed hard domains play a pivotal role in conferring self-healability and generating stress-induced crystallization(SIC)of polytetramethylene ether glycol(PTMEG)chains during large deformation,which not only facilitates the chain mobility for heat-responsive dynamic exchange of hydrogen bonds and oximecarbamate but also dissipate external force during stretching to help the SIC evolution of PTMEG chains.The SIC domains act as physical crosslinking junctions and reinforcing phase,resulting in remarkable strengthening and toughening.This strategy could enlighten researchers in academia and industry to develop strong and tough elastic materials.In the meantime,the unique comprehensive performance of the assynthesized elastomer confers it with potential practical use in engineer-grade fields of puncture-resistant tire sealant and durable protective coatings.