Study On The Preparation And Properties Of The Self-Healing Polymer Based On Diels-Alder Reversible Covalent Bonding

In the natural world,most creatures can repair and heal independently after local injury,but synthetic polymer material does not have the "self-healing" ability.Micro-cracks produced in the internal of polymer materials can lower the material performance and service life,and even lead to completely loss after a long time usage.For simulating self-healing process of organism,researchers introduced the concept of self-healing into polymer material in order to get longer,more reliable,more economical new smart functional materials.This kind of smart material has potential applications in microelectronics,bionic medicine,paints,and other related fields.There are so many methods to prepare the self-healing materials,but one of the most effective methods is to introduce the reversible covalent bonded into the polymer materials.As one of the most effective reversible covalent reactions,DA reaction is applied extensively in synthesis of hexatomic ring and polymers,and can be performed under mild reaction conditions.When heated to an appropriate temperature range,the adducts of the DA reaction undergo the reverse reaction?i.e.,retro-DA reaction?and regenerate the original reactants.It also has many outstanding properties,such as aqueous promotion,structure controllability,being widely used in the preparation of polymers,and so on.DA reaction between furan ring and bismaleimide is the most typical representative in Diels-Alder reaction system,exhibiting tremendous application value and prospects for development in the field of science and technology engineering and advanced technology,having become a new and frontier subject in the field of materials science.In this paper,the polyurethane prepolymer end-capped with furan rings?named HTX?by designing the molecular chains based on hexamethylene diisocyanate trimer was firstly prepared.Then the polyurethane HTX-PU was synthesized by taking the furan ring and maleimide as the DA reaction group.The polymer HTX-PU was tested by FTIR,DSC,TGA,POM and tensile testing method,then.The results of FTIR indicated that the absorbed peak at 1776 cm^-1 meaning the synthesis of DA group.The DSC testing results showed that the glass transition temperature of HTX-PU was-45.94 ?,and the initial temperature of the retro-DA reaction was 88.93 ?.The TGA testing results exhibited that the HTX-PU system was stable in the range of 50¹50 ?.The POM was used to observe the self-healing process of the HTX-PU,and the results display that the cracks could be healed completely after 6 hours at 110 ?.The self-healing efficiency of HTX-PU calculated with tensile testing method reached to 92.63 %.Subsequently,the second polyurethane prepolymer end-capped with furan rings?named FG-IP-PT?by designing the molecular chains based on isophorone diisocyanate trimer was prepared.Then the polyurethane FG-IP-PT-B was synthesized by taking the furan ring and maleimide as the DA reaction group.The polymer FG-IP-PT-B was tested by Fourier Transform Infrared Spectroscopy?FTIR?,Differential Scanning Calorimetry?DSC?,Thermogravimetric Analysis?TGA?,Polarizing Microscope?POM?and tensile testing method,then.The results of FTIR indicated that the absorbed peak at 1776 cm^-1 meaning the synthesis of DA group.The DSC testing results showed that the glass transition temperature of FG-IP-PT-B was-69.40 ?,and the initial temperature of the retro-DA reaction was 83.61 ?.The TGA testing results exhibited that the FG-IP-PT-B system was stable in the range of 50¹50 ?.The POM was used to observe the self-healing process of the FG-IP-PT-B,and the results displayed that the cracks could be healed completely after 6 hours at 80 ?.The self-healing efficiency of FG-IP-PT-B calculated with tensile testing method reached to 87.96 %.Finally,the third and the fourth resins end-capped with furan rings?FGE-D2000 and FGE-T5000?by designing the molecular chains based on polyetheramine D2000 and polyetheramine T5000 were prepared.Then the polymer FGE-D2000-BDM and FGE-T5000-BDM were synthesized by taking the furan ring and maleimide as the DA reaction group.The polymer FGE-D2000-BDM and FGE-T5000-BDM were tested by FTIR,DSC,TGA,POM and tensile testing method,then.The results of FTIR indicated that the absorbed peak at 1776 cm^-1 meanning the synthesis of DA group.The DSC testing results showed that the glass transition temperature of FGE-D2000-BDM was-54.50 ?,and the initial temperature of the retro-DA reaction was 69.59 ?;the glass transition temperature of FGE-D2000-BDM was-67.52 ?,and the initial temperature of the retro-DA reaction was 88.03 ?.The TGA testing results exhibited that the FGE-D2000-BDM and FGE-T5000-BDM systemes were stable in the range of 50¹50 ?.The POM was used to observe the self-healing process of the FGE-D2000-BDM and FGE-T5000-BDM,and the results displayed that the cracks could be healed completely after 6 hours at 80 ?.The self-healing efficiency of FGE-D2000-BDM calculated with tensile testing method reached to 71.04 %,and the self-healing efficiency of FGE-T5000-BDM calculated with tensile testing method reached to 88.46 %.