Preparation And Properties Of Polyurethane Elastomer With Synergistic Effect Of Shape Memory Self-healing

Giving the polyurethane material a shape memory function or a self-repair function can greatly improve the material’s anti-mechanical aging performance,service life and reliability,and reduce the use cost and safety hazards of the device.However,with the advancement of technology and the improvement of use requirements,a single shape memory function or self-repair function gradually cannot meet the various environmental changes and external damage faced by polyurethane materials in the actual application process.In order to solve this contradiction,it is necessary to study the structural properties of polyurethane materials,the shape memory effect and the principle of self-repair,and combine theory with practice to develop a synergistic effect of shape memory and self-repair functions with application potential.Polyurethane material.This research is of great significance for the development of multifunctional intelligent polyurethane materials,expanding the application range of polyurethane materials,extending the service life of materials,and reducing the waste rate.The basic idea for the synthesis of shape memory self-repairing synergistic polyurethane elastomer is:（1）First,synthesize a polyurethane elastomer（SMPU）with excellent shape memory function;（2）functionally modify the shape memory elastomer to improve On the basis of polyurethane elastomer,blocks with self-repairing functional groups are introduced to give it self-repairing ability.This thesis starts with the research idea of polyurethane material"Shape memory assisted self-healing（SMASH）",and synthesizes a temperature-responsive shape memory polyurethane elastomer containing a large number of dynamic hydrogen bonds.Based on the experiment,the sample was modified to change the block components on the molecular chain of the material to obtain a new self-repair function on the basis of retaining the original shape memory function.The main contents are as follows（1）A multi-step method was used to synthesize a series of hydrogen bond polyurethane elastomers（Hydrogen bond polyurethane elastomers,HPEs）with adjustable light-curing site aggregation density using PEMTC as the main chain extender.PEMTC can be used as a chain extender to introduce active-C=C into HPEs,induce hydrogen bond aggregation after UV irradiation,and enhance the microphase separation structure of HPEs;HPEs have good thermal stability,and the decomposition temperature is around 350℃;The softening temperature is around 50℃;for different components of HPEs,the increase in hydrogen bond aggregation caused by the increase of PEMTC content can enhance the heat resistance of the material and increase the softening temperature;the mechanical tensile test compares the various components of HPEs,confirming Hydrogen bond aggregation can improve the mechanical properties of materials.With the increase of PEMTC content,the tensile strength of HPEs has increased from12.1 MPa to 41.5 MPa;the maximum deformation has increased from 642%to917%;the synthesized HPEs have been proved by SME testing.The material has good shape memory characteristics,the shape fixation rate is between 86.2%and 98.0%,and the shape recovery rate is between 73.5%and 93.7%.The stability of the shape memory effect of HPEs proves the rationality of the molecular segment design of the polyurethane material in this experiment,and provides a research foundation for the next synthesis of shape memory self-repairing synergistic polyurethane elastomer materials.（2）Using the block copolymerization method,using HPDS as the chain extender,the dynamic covalent bond of the SS bond is introduced into the HPEs molecular chain segment,and the shape memory self containing both dynamic SS bond and hydrogen bond is synthesized according to different proportions.Repair synergistic polyurethane elastomers（Disulfide bonds polyurethane elastomers,DSPEs）,explore the self-healing effect of polyurethane under different conditions after mechanical damage,and study the SMASH effect of polyurethane materials.The introduction of PEMTC and HPDS leads to the formation of microphase separation structure of DSPEs;DSPEs have good thermal stability,and the decomposition temperature is around 350°C;the best self-repair temperature range of materials is between 60°C and 80°C;the introduction of HPDS makes Compared with HPEs,the mechanical properties of DSPEs have been reduced,but they are still relatively good.The material has a maximum elongation of 511.7%,a tensile strength of 7.16 MPa,a toughness of17.82 MJ·M^-3,an elastic modulus of 4.23 MPa and a self-healing performance of 91.7%.（3）The dynamic D-A bond was introduced into the HPEs molecular chain through the D-A addition reaction to synthesize D-A bond-containing polyurethane elastomers.Self-healing performance.The dynamic D-A bond generated by the addition reaction of furfuryl alcohol and 4,4-diphenylmethane bismaleamide was introduced into DAPEs to obtain self-healing ability of DAPEs.Due to the low thermal decomposition temperature of the D-A bond,DAPEs have good thermorheological properties.After a short time of heating,the surface is slightly melted and the mechanical damage cracks are filled,and the repair is completed after cooling and solidification.The crack repair of DAPEs was observed by scanning electron microscope,and it was confirmed that the synthesized DAPEs had good self-healing properties for different degrees of mechanical damage.