Study On Preparation And Properties Of Self-healing Hyperbranched Polyamide-amine Elastomers

Hydrogen bond has rich form of formation and excellent thermoreversible properties.Therefore,preparing self-healing supramolecular polymer materials through hydrogen bonding self-assembly has become a hotspot in recent years.However,the high degree of directionality and saturation of the hydrogen bonds make the supramolecular polymers tend to crystallize,and make it harder to obtain high elastic materials.Hyperbranched polyamidoamine(HPAMAM)has a highly branched molecular structure,so that the formation of crystallization is restricted and the glass transition temperature Tg is reduced.In this study,HPAMAM was applied to prepare self-healing supramolecular elastomer by utilizing its highly branched structure.At the same time,to solve the poor mechanical properties of hydrogen bond type self-healing supramolecular elastomers,ion bond cross-linking network had been introduced.Due to that ionic bond has strong bond energy and ion cluster phase can be formed by adjusting ion concentration,the mechanical properties of elastomers were enhanced.As a result,the supramolecular elastomer material with good mechanical property and excellent self-healing property was prepared.Firstly,in this study,hyperbranched polyamidoamine(HPAMAM)was synthesized by ABn type monomer polycondensation method,and three different supramolecular polymer HC,HU and HM were prepared based on HPAMAM.The structure of HPAMAM and HC,HU and HM were characterized by FT-IR,XRD and DSC.The thermal properties,mechanical properties and self-healing properties of these three polymers were studied by TGA and tensile tests.The test results showed that the highly branched molecular structure of HPAMAM could reduce the Tg of supramolecular polymer,and that polymer HC and HM are elastomeric materials at room temperature.After further introducing the ion bond cross-linking network,mechanical properties and self-healing properties of polymers were effectively improved by slightly increasing the Tg of polymers and maintaining the high elasticity of them at room temperature.Secondly,based on supramolecular polymer HM,a series of supramolecular elastomers with excellent machanical and self-healing properties were prepared by optimizing thesynthesis reaction process.Structures of the elastomers were analyzed by FT-IR,XRD,DSC,SAXS and solubility analysis.The inner association of thermal properties,viscoelastic properties,machanical properties and self-healing properties with the structures of these elastomers were studied.The self-healing mechanism was studied by self-healing mechanism model and temperature-dependent infrared test.The results showed that this series polymers were amorphous self-healing supramolecular elastomers with both hydrogen bonding crosslinking network and ionic crosslinkage network.These polymers all had a Tg below room temperature and part of them had ion clusters phase.As the formulation changed,the mechanical properties of elastomers changed.Among these elastomers,HM-E-C1.5 had the best mechanical property with the tensile strength was 3696 KPa and the elongation at break was 293%.The healing efficiency of elastomer decreased with the increase of the parking time,and increased with the increase of the healing time.When the parking time was 0 min,the healing efficiency of the elastomer HM-E-C1.5 reached 91.15% after healing 24 hours at room temperature.The results showed that this study proposed a new effective strategy of preparing self-healing elastomer.Through this strategy,the supramolecular elastomers with excellent self-healing properties and strong mechanical properties at room temperature had been successfully prepared,which provided theoretical basis and practical research experience for broadening the research area of self-healing elastomers.