Self-healing PDMS Polymer Materials Based On Coordination Bond

Degradation,damage,and failure are natural consequences of material applications.Engineering research has been focused traditionally on either the design of new materials with increased robustness or the development of nondestructive evaluation methods for material inspection,yet all engineered materials eventually fail.In contrast,biological systems approach this same dilemma in an elegant fashion:by self-healing.Self-healing materials exhibit the ability to repair themselves and to recover functionality using the resources inherently available to them.Whether the repair process is autonomic or externally assisted(e.g.,by heating),the recovery process is triggered by damage to the material.Self-healing materials offer a new route toward safer,longer-lasting products.This material can improve the material functionality,reliability and life and therefore the development of self-repairing material has received attention for researchers around the world.The dissertation consists of three parts.Firstly,we synthesized a solvatochromism and self-healing polymer complex using Cobalt-triazol coordination bond.Secondly,we synthesized a highly stretchable and self-healing polymer complex using iron-triazol coordination bond.Thirdly,we synthesized a room tempreature self-healing polymer complex using Zinc and schiff reaction.1.Solvatochromism and self-healing properfties of polymer complex based on Cobalt-triazol coordination bondWe synthesized line cross-linked polymer TIA-PDMS using 5-(4H-1,2,4-triazol-4-yl)isophthalate(TIA)and NH2-PDMS-NH2,and then synthesized Co-TIA-PDMS polymer film by coordinating cobalt with triazole.This polymer film has solvatochromism properties under the influence of methanol or water.It can change from four coordinated numbers to six-coordinated numbers,while the color changes from blue to pale white.The maximum sthetched length of such a polymer film is 5.6 times of its original length,with Young's modulus of 1.12 MPa.By studying its self-healing properties,we got a conclusion that higher temperatures and longer time are conducive to self-healing efficiency.The most suitable temperature is 120 ?,and after self-healing at this temperature for 24 h the efficiency reached 47.3%,while the self-healing efficiency reached 33.5%at room temperature under the influence of methanol.2.Self-healing and Mechanical properties of polymer complex based on Iron-triazol coordination bondWe synthesized Fe-TIA-PDMS polymer film by coordinating Iron(in)with triazole and this polymer film shows good self-healing properties and mechanical properties.By studying the mechanical properties,the polymer film can be stretched to 34 times of its original length,with Young's modulus of 0.46 MPa.By measuring the tensile curve it showed good elasticity.By studying its self-healing properties,the polymer could be healed at mild conditions,when the temperature is 60 ? and healing time is 20 h,the self-healing efficiency can be more than 90%,while higher temperatures and the healing time will accelerate the self-healing process.3.Self-healing properties of polymer complex based on Zn-schiff coordination bondWe synthesized line cross-linked polymer PDMS-A from condensation reaction of NH2-PDMS-NH2 and 1,3-dimethylbutyl,4-chloro-2 phenol and then synthesized Zn-PDMS-A polymer film by coordinating Zn with Schiff base polymer.We studied the effects of PDMS molecular weight(700,2500,5000)and the ratio of ligand to metal.It indicates that when the molar ratio of ligand to metal is I:0.5,the molecular weight of the three kind polymer films are able to self-healing at room temperature completely.When the molsar ratio of ligand to metal was 1:1,the film with 700 molecular weight can not self-healing,however the film with 2500 and 5000 molecular weight are able to self-healing completely.Through the small molecule simulation,we got two different crystal structures of different molar ratios.Then we analyzed self-healing mechanism.