Preparation And Characterization Of Self-healing Polymers Enhanced By The Synergy Of Multiple Mechanisms

With the development of polymer science,polymer materials play an increasingly irreplaceable role in the production and life.However,polymer materials will occurr a certain degree of damage in the process of daily use,which seriously restricts the stability and lifetime of the materials.The introduction of self-healing function could endow higher safety and stability and prolong the lifetime of the materials.Therefore,it is important to develop polymer materials containing self-healing property.Intrinsic self-healing materials repair damage by the internal dynamic reversible interactions,which chould rapidly open and reconstruct.But these dynamic interactions are difficult to carry large loads,resulting in low mechanical strength.High mechanical strength is a prerequisite for the use of polymer materials.Therefore,improving the mechanical strength of self-healing materials through appropriate design is a problem that must be solved on the development of self-healing materials.Aiming at the above problems,a series of novel multi-mechanism synergistic polymer materials by adjusting the structure of raw materials and the ratio of Zn(II)was synthesized in this paper.The main results are as follows:(1)A series of cross-linked polymers P₁-P₆ with different microstructures were synthesized by one-pot method with different structures and proportions anhydrides,diols and triols as raw materials,which were realized by changing the structures of cyclic anhydrides and diols.The characterizations of structures and properties for these polymers were researched in datail.The results show that these afforded cross-linked polymers are all amorphous.The thermal stability was greatly improved and glass transition temperature(T_g)was decreased by introduction of pyridine groups.The cross-linked degree of 50%has the strongest thermal stability in this system.A series of novel cross-linked network polymers P_n-Zn_x:y(n=1-6,x:y represents the molar ratio of anhydride to Zn(II))based on coordination interaction were prepared by adjusting the structure of monomer and the molar ratio of anhydride to Zn(II).The results show that the metal-ligand coordination bond is successfully formed;the thermal stability of P_n-Zn_x:y was weakened and the T_g was reduced.With the increase of Zn(II)feeding amount,the thermal stability for high temperature was increased and T_g was gradually decreased for P_n-Zn_x:y polymers.The self-healing property was characterized by optical microscopy,and it was found that the cross-linked network polymers P_n-Zn_x:y had obvious self-healing property after healing at 25 ^oC,which the demage almost completely disappeared under the microscope.Meanwhile,the self-healing property of the materials can be effectively controlled by adjusting the molar ratio of anhydride and Zn(II).(2)A series of imine bond cross-linked polyetheramine(TA-PPG),polyurea material(TH-PPG),imine bond cross-linked polyurea material(TH-T-PPG)with different interaction mechanisms were synthesized by polycondensation method by polyetheramines with different molecular weights,diisocyanates with different structures and proportions,trihydroxy-terminated polyetheramines and terephthalaldehyde as raw materials.The results show that the polymers are all amorphous and exhibit excellent thermal stability.T_g increases with the increase of the number of benzene in the polymer molecular chain and the introduction of imine bonds.The self-healing efficiency is TH-PPG>TH-T-PPG>TA-PPG,which is opposite to the mechanical strength of the three polymers.These polymers all exhibit excellent recyclability and remodeling properties.A series of multi-mechanism synergistic polymers Zn_m:n-TA-PPG,Zn_m:n-TH-PPG and Zn_m:n-TH-T-PPG were prepared by adjusting the molar ratio of polymer and Zn(II).The results show that the metal-ligand coordination bond is successfully formed.The thermal stability of these polymers containing coordination interaction still maintains high and T_g is slightly increased.The polymers have excellent self-healing property and excellent mechanical strength.The research work of this paper provides certain design concepts and ideas for the reinforcement and toughening of self-healing polymer materials.Finally,we discuss the further work,and we can continue to explore the self-healing mechanism and the factors that affect polymer properties...