Preparation And Research Of Shape Memory Composites Reinforced By Nanomaterials Modified By Polydopamin

Shape memory polymers(SMP)are a class of smart polymers that are able to switch freely between the temporary shape of a design and its original shape.SMP was widely used in the research and development of new intelligent materials such as drives,self-healing materials,intelligent textiles,biomedicine and aerospace because of its large deformation,low density,diverse driving methods and good biocompatibility.However,due to the lower mechanical properties and modulus of SMP materials,this limits their use in advanced materials.Many studies have shown that the incorporation of different nanostructured fillers into the SMP matrix can enhance the mechanical properties of the material.However,it should be noted that in some direct practical applications,new polymer devices still have relatively poor mechanical properties.Therefore,in order to overcome this difficulty,it is necessary to optimize the dispersion of nanofills and the interface interaction with materials through appropriate modification methods.In this thesis,using trans-1,4-polyisoprene(TPI)as the research matrix of SMP materials,a series of polydopamine-modified nanofills were prepared by polydopamine(PDA)modified nano-fillers for different nanomaterials,and they were introduced into the TPI matrix,and the thermal stability,mechanical properties and shape memory properties of TPI composites were systematically studied,and finally the enhancement mechanism was elaborated.The work of the thesis mainly consists of the following three parts:(1)Using the oxidative polymerization reaction of dopamine(DA),a Si O2@PDA nano-filler with a core-shell structure was prepared,and it was introduced into the TPI matrix,and a series of TPI composites containing different Si O2@PDA contents were prepared.It was compared with TPI composites with only Si O2 added.The thermodynamic properties and shape memory properties of TPI composites were tested and characterized.The results showed that PDA-modified Si O2 nanoparticles could maintain excellent shape memory performance while enhancing the thermodynamic properties of TPI composites.(2)By functionalization modification of the GO nano-sheet layer by oxidative polymerization reaction of dopamine,GO@PDA nano-fillers were prepared,and a series of TPI composites with different GO@PDA contents were prepared by introducing them into the TPI matrix as nanofills,which were compared with TPI/GO composites.The thermodynamic properties and shape memory properties of TPI composites were tested and characterized.The results show that the PDA-modified GO has good dispersion and interfacial compatibility,and the thermodynamic properties of the corresponding TPI/GO@PDA shape memory composites had been significantly improved,and the enhancement effect is better than that of TPI/GO composites.(3)By dopamine oxidation polymerization reaction,PDA coated HNTs@PDA nanofills were prepared,and then introduced into the TPI matrix by melting and blending,and TPI/HNTs and TPI/HNTs@PDA shape memory composites were prepared,respectively.The microstructure and properties of HNTs before and after surface modification were studied.In addition,the effects of PDA coatings on the dispersion of HNTs in the TPI matrix,the interfacial interaction between HNTs@PDA and matrix,and the thermodynamic properties and shape memory properties of TPI/HNTs@PDA composites were systematically studied and analyzed.