Preparation And Study Of High Performance Self-healing Brominated Butyl Rubber Ionomer

Butyl rubber(including halogenated butyl rubber)has excellent air tightness,weather resistance,shock absorption,electrical insulation and chemical corrosion resistance.It is widely used in automobile tires,medical consumables and other fields,so it is considered as an important strategic material.However,at present,the butyl rubber materials in China are facing three major dilemmas:(1)the harsh synthesis conditions and complex production technology of butyl rubber make most of the butyl rubber in China relys on imports;(2)in order to protect the just started butyl rubber industry,the country imposes a 25% tariff on imported butyl rubber,so the price of butyl rubber remains high for a long time;(3)covalently crosslinked butyl rubber because of the lack of self-healing performance and reprocessability,it is difficult to recycle after service damage,resulting in a large amount of industrial waste and environmental pollution,which is not conducive to the "green" development and sustainable development of society.Self-healing and recyclable materials constructed by dynamic covalent networks and supramolecular interactions are expected to solve the above problems.However,the low bond energy,high polarity,easy to absorb and hydrolyze and complex synthesis of dynamic bond and supramolecular interaction make this kind of materials have low mechanical properties,weak environmental adaptability and difficult to large-scale production,which seriously limits its practical promotion and application.In order to overcome the above problems,a novel pyridine derivative was used to graft brominated butyl rubber in situ to prepare high-performance and self-healing ionomers.The self-healing and mechanical properties of BIIR ionomers were systematically controlled by the electron-donating effect,hydrophobic effect,resonance isomerization effect and carbon black reinforcing effect of pyridine derivatives.The influence of four kinds of effects on molecular structure,network structure and aggregation state structure of BIIR ionomer was deeply studied.The relaxation transition behaviors of molecular chain and ionic aggregates in different systems were analyzed.The structure-activity relationship of BIIR ionomer was proposed by connecting them with the macroscopic properties of materials.The ionomer with high mechanical properties,high self-healing efficiency and recyclability was successfully prepared.It is helpful to promote the practical application and sustainable development of BIIR ionomer materials in the field of automobile tires and medical consumables.The specific research contents of this paper are as follows:(1)BIIR ionomers with adjustable mechanical properties and self-healing properties were prepared by using pyridine derivatives with different electron-donating effect.The electron-donating effect of pyridine derivatives mainly plays three roles: one is that the electron-donating effect leads to the increase of basicity and reactivity of pyridine derivatives,which is conducive to the ionic modification of BIIR,the increase of grafting rate,and the enhancement of the interaction between single pyridine cation and bromine anion;the other is that the electron-donating effect brings stronger dispersion,which is conducive to the ionic modification of BIIR.The results show that π-π stacking structure is formed between the six membered rings of pyridine,which induces the formation of regular and larger ionic aggregates,thus improving the macro mechanical properties of ionomers;the third is the plasticization of electron donor substituents,which reduces the interaction energy of dimers,reduces the relaxation transition temperature and activation energy of ion clusters,which is conducive to increasing the mobility of confined molecules and ionic clusters,thus improving the self-healing efficiency of BIIR ionomer(2)The self-healing BIIR ionomers with water resistance and acid-base resistance were prepared by constructing the dynamic pyridine ion interaction protected by hydrophobic micelles.Small molecule model experiments show that hydrophobic tert-butyl and hydrophilic pyridine/bromine ion bonds can form micelle structure,which creates a waterless internal environment for ion bonds and stabilizes polar ion interaction.In the BIIR ionomer,the micellar structure protects the internal dynamic ion network from the invasion of external water molecules and acid-base molecules,and ensures the stability of the ionic network under harsh environmental conditions.In addition,with the protection of hydrophobic effect,the ionomers show excellent self-healing properties in water and acid-base solutions,indicating that the ionomers have strong environmental adaptability and viability.Combined with the excellent properties of ionomer,self-healing sensors and self-healing dielectric elastomers with strong environmental adaptability were developed,which broadened the application range of brominated butyl rubber ionomer.(3)Carbon black reinforcing the self-healing BIIR ionomer modified by pyridine derivative can significantly improve the mechanical properties of the material,while maintaining the self-healing ability and reprocessability of the material.Firstly,the interface coupling between carbon black and pyridinium salt was proved by using the model small molecule system,and then carbon black was introduced into the ionomer system.The introduction of carbon black does not change the state of ionic aggregation,maintains the integrity of the ionic network,and generates more bound rubber,which increases the multistage of the micro network structure.The dynamic interface coupling between carbon black and ionic aggregates is formed by π-cation and hydrogen bond,which changes the molecular dynamics of all levels in ionomer.The interfacial coupling increases the relaxation time and relaxation activation energy of the ionic aggregates and the electrode polarization process,which significantly improves the mechanical properties of the ionomers,while the chain relaxation is not affected,which makes the ionomers still have self-healing properties and reprocessability.Finally,the synergistic effect of carbon black reinforcing effect and electron-donating effect on the mechanical properties and molecular dynamics of BIIR ionomer modified by pyridine derivatives was investigated.It was found that the synergistic effect further improved the mechanical properties and reprocessability of BIIR ionomer.(4)The BIIR ionomer with high mechanical properties and high self-healing efficiency was constructed by means of resonance isomerization of4-alkylaminopyridine derivatives.The 4-alkylaminopyridine derivatives have been grafted onto the main chain of BIIR,and the resonance structure of the protonated pyridine ions will change due to their special structure.The resonance isomerization of pyridine ions mainly brings about three functions: first,the positive charge is transferred from the pyridine ring to tertiary amine structure,weakening the interference of steric resistance of tertiary amine,and favorable for the ionic interaction;the second is the enhanced induced force and dispersion force,which is conducive to the stable π-π stacking of pyridine ions,and then obvious phase separation structure will occur,forming a larger and regular phase separation structure.The third is that the molecular dynamics of the ionomer exhibits the multi-level relaxation scale,including the relaxation transition of the ionic cluster and electrode polarization.The relaxation time and activation energy of the two groups increase with the increase of the ionic interaction.In addition,there is also the relaxation movement of the whole ionic aggregates caused by larger space effect,which is conducive to the relaxation of ionic network and the improvement of the self-healing efficiency of the ionomer.Therefore,the resonance structure transition effect endows the BIIR ionomer with high tensile strength and adjustable self-healing efficiency,which ensures the simultaneous occurrence of high mechanical properties and high self-healing efficiency.The simple processing technology and excellent comprehensive properties make BIIR ionomer be expected to be applied in the fields of intrinsic self-healing tire,medical consumables and waste butyl rubber recycling,and further promote the commercial development of self-healing materials.