Preparation Of Intrinsic Self-Healing Polymers Via Isonitrile-Involved Multi-Component Reactions

The multi-component reactions(MCRs)can combine three or more starting reactants to form a single product containing the main structural fragments of all components.It is widely used in organic synthesis,especially for drug synthesis.The biggest advantage of MCRs is that products of diversity can be obtained by simply changing the starting reactants.Both the Passerini reaction and the Ugi reaction are typical representatives of MCRs.These reactions have the advantages of mild reaction conditions,no catalysts,and atomic savings.With the development of chemical science,the MCRs has gradually evolved from the synthesis of small molecules to the field of polymer research.In this paper,the renewable resource furfural is used as raw material to synthesize linear polymer containing furan ring through multi-component reaction,then through Diels-Alder reaction to obtain cross-linked polymer.Due to the reversible reaction of the Diels-Alder reaction,it has self-repairing properties.1.Synthesis of two isonitrile compounds from amines.Using the Passerini reaction,a linear polymer containing a furan ring was prepared.Crosslinking of linear polymers with N,N'-(4,4'-methylenediphenyl)bismaleimide(BMI)resulted in two crosslinked polymers.Polymers are tested for solvent resistance,thermal properties,mechanical properties,repair capabilities,etc.The healing efficiencies were 55.8% and 74%,respectively,and the solvent resistance was good.2.Using Ugi reaction,a series of furan ring-containing linear amide polymers are prepared by switching raw materials,and self-healing polymers are prepared by crosslinking with BMI.Aromatic rings are introduced into linear polymers to increase heat resistance and hardness.The repairing ability of the polymer can reach 90% or more,and the cross-linked polymer containing the aromatic ring-type polymer is higher in strength,relatively lower in toughness,and the self-repairing effect is42%.The cross-linked polymers that do not contain aromatic ring-shaped polymers after D-A reaction have good toughness and relatively good self-repairing ability.3.Ugi and Passerini reactions are used to introduce disulfide bonds and D-A covalentbonds to reduce the repair conditions of the self-healing polymer so that the polymer can be repaired under UV light.The repair performance was tested by the tensile stress-strain test of the original sample and the repaired sample,in which the UV light irradiation cured the polymer surface,but the mechanical properties weakened obviously and the healing efficiencies are about 60%.In addition,two cross-linked polymers that contain both hydrophilic segments and reversible D-A covalent bonds are designed,so that they have the ability of absorbing water and self-healing.Equilibrium swelling ratio was 49.3% and 65.3%,at 30?.