Actuation Properties Of Epoxy-Based And Poly(Vinyl Alcohol)-Based Shape Memory Composites

Shape memory polymer can recover its original shape by external stimulation.This feature has established its important status in the field of intelligent materials.The composites have excellent comprehensive properties,but the applications of directly heating-induced shape memory polymer composites are limited in heat source,working temperature,thermal conduction,controllability,and so on.Based on predesigned shape memory properties,the study of environmentally friendly,quickly responding,and non-contact control shape memory polymer composites will availably expand their possible applications,which has profound theoretical and practical significances.The shape memory properties of shape memory composites can be designed by choosing and controlling modifier(functional phase)and shape memory polymer matrix.The shape memory composites can be constructed by functional phase(such as metal,carbon,semiconductor,mesoporous materials,fiber,or other inorganic particles)and shape memory polymer matrix.In this thesis,light induced,water induced,electro induced novel shape memory composite were constructed by appropriate functional phase and shape memory polymer matrix based on driven-function oriented.The shape memory properties,key influence factors,and relevant mechanisms of shape memory composites were intense researched.The main works are as follows.The novel water induced thermoset epoxy-based shape memory composite with 3D microvoid on its surface was presented based on the chemical interaction between sodium dodecyl sulfate with amphiphilic molecular structures and water.The 3D microvoids of the sodium dodecyl sulfate/epoxy-based water induced shape memory composites surface benefits the interactions between water and the composite to trigger the water induced shape memory effect.The chemical interaction,physical swelling effect,temperature,and thickness have an important influence on water induced shape memory properties of the composite.The oxygen-containing functional groups of gold nanoparticles benefit to enhance the interaction between water and the gold nanoparticles/ poly(vinyl alcohol)-based shape memory composite.The composites can recover their original shapes at a lower temperatur e.The water induced shape memory recovery process of gold nanoparticles/ poly(vinyl alcohol)-based shape memory composite was completed in 9min at 30 oC.The waterinduced shape recovery of the gold nanoparticles/poly(vinyl alcohol)-based shape memory composite is attribute to the swelling plasticizing effect of water on the composite.The electro induced shape memory composites were prepared by reduced graphene oxide paper and carbon nanotube paper(functional phase)with epoxy-based and poly(vinyl alcohol)-based shape memory polymer,respectively.The carbon nanotube paper and reduced graphene oxide paper have excellent conductivity.The reduced graphene oxide paper/ epoxy-based shape memory composite completed shape memory recovery process in 5s,when the voltage controlled at 6V.The shape memory composites show excellent electric induced shape memory properties,due to highly efficient transmission of electrical resistive heating from functional phase(reduced graphene oxide paper and carbon nanotube paper)to their shape memory polymer matrix.The new designed shape memory composites are more energy efficient with lower applied voltage and more convenient with faster response to complete the shape recovery process which provide experimental basis to design novel efficient electric induced shape memory composites.The light induced shape memory composite was constructed by gold nanoparticles with perfect photo-thermal effect(functional phase)and poly(vinyl alcohol)-based shape memory polymer(matrix).The gold nanoparticles/poly(vinyl alcohol)-based composite displayed excellent light induced shape memory properties with recovery ratio of nearly 100% in 14 s.Gold nanoparticles can efficiently convert light energy into thermal energy,which transfer photo-induced shape memory effect from the molecular level to macroscopic movement of the gold nanoparticles/poly(vinyl alcohol)-based composite.Based on the above analysis and discussion of the design principle,fabrication,and shape memory properties of water induced shape memory composite,and electric induced shape memory composite,the novel shape memory composite was constructed by gold nanoparticles and carbon nanotube paper(functional phase)with poly(vinyl alcohol)-based shape memory polymer matrix.The light induced shape memory recovery ratio of the composite realized 100% in 10 s.The light induced shape memory properties of the composites was significantly improved,comparing with the shape memory composite of corresponding single functional phase.Moreover,the gold nanoparticles/ carbon nanotube paper/ poly(vinyl alcohol)-based composite possessed light induced,water induced,and electric induced shape memory properties.The water induced shape memory recovery process of the novel composite was completed in 6min at 30 oC.The shape memory composite completed shape memory recovery process in 35 s,when the voltage controlled at 3V.These shape memory properties were significantly improved,comparing with the light induced shape memory composite,water induced shape memory composite,and electric induced shape memory composite of corresponding single functional phase.The gold nanoparticles and carbon nanotube paper in the novel shape memory composite make the composite have the ability induced by light,water and electric.The optimal induced method of composite was programed by interaction of gold nanoparticles and carbon nanotube paper.The poly(vinyl alcohol)-based shape memory polymer not only has the loading affect,improved the interaction with two functional phases,but also is able to maintain the good shape memory properties.The composite could convert light energy,chemical energy,and electrical energy into mechanical energy to indirect induced shape memory effect,which had better adaptability to the environment.The study has important implications for the development and application of shape memory composites.This provides an ideal material platform for development of novel smart material.