Biomimetic 3D Printing Of Polylactic Acid Based Shape Memory Material And Its Deformation Characteristics

Smart material refers to a new material that can perceive the external environment and its own state,make a judgment,and then change its parameters according to the preset target.As the materials themselves are very sensitive to the changes of the surrounding environment,intelligent materials have attracted great attention in the fields of brakes,intelligent robots,tissue engineering and bio-medical treatment.Among the complex types of smart materials,shape memory polymer(SMPs)has a broad application prospect in biomedical,flexible actuator,intelligent sensor,electronic component,flexible robot and other fields due to its good mechanical properties,fast response rate and good bio-compatibility.However,most shape memory polymers have too high deformation temperature and a single deformation process,which makes it difficult to achieve the characteristics of high controllability,good mechanical properties and coordination of multiple response modes,so they cannot be widely used in complex working conditions.At the same time,with the increasing practical demand of engineering,many bottleneck problems,such as shape memory material design and preparation technology,need to be solved urgently.Compared with artificial materials in engineering industry,after one hundred million years the many creatures in nature,in the limited conditions,using its own subtle structural design and optimization of material coupling,improved the mechanical properties and adaptive ability,for high precision,multiple response,shape memory composites complex deformation,Lixue Gao performance promotion provides an important train of thought.Therefore,this paper to solve the problem of high deformation temperature of SMPs,single deformation process and the way of a single response problem,based on hierarchical porous wood,fibre winding structure bionic structure design model for material,with polylactic acid(PLA)as the matrixmaterial,the linear semicrystalline polymer poly caprolactone(PCL),carbon(C),graphene oxide(GO)modification such as adding phase,using 3D printing manufacturing technology,the preparation of gradient structure controlled shape memory polymer material,in order to realize the order of multiple response mode shape changes.The specific research contents and main conclusions are as follows:(1)PLA/PCL-SMP composite with good mechanical properties and shape memory properties was successfully prepared by direct writing 3D printing with polylactic acid material as the matrix,semi-crystalline linear polyoligolactone as the modified additive phase and methylene chloride as the solvent.The addition of polyoligolactone widens the temperature response interval of composite materials.With the increase of polyoligolactone content,the deformation temperature decreases by about 10? at most,and the sequential deformation under temperature control is realized.At the same time,PLA/PCL-SMP composite material was used to successfully 3D print the u-shaped recovery,spiral recovery and flower sequence recovery samples,showing a good shape fixation rate and shape recovery rate.The composition system of PLA/PCL-SMP composite was optimized to provide a material basis for the design of3 D printable high-performance bionic shape memory composite.(2)A 90°/0°biomimetic lamellar fiber oriented model was established based on the directional arrangement structure characteristics of wood cell wall fiber filament winding.PLA/PCL-SMP composite material was optimized as the matrix material.The introduction of the directional arrangement of carbon fiber can significantly improve the thermo-mechanical properties and mechanical properties without affecting the deformation temperature.The maximum energy storage modulus can reach 3241 MPa,the maximum tensile strength can reach 63 MPa,and the maximum elongation at break can reach 39.7%.(3)In the biomimetic carbon fiber reinforced shape memory composites,the introduction of carbon fiber hindered the movement of the molecular chain segment in the PLA/PCL-SMP composite matrix,limited the slip of the molecular chain segment,and improved the shape recovery rate.At the same time,as the reinforcing phase,carbon fiber fixed more internal stress and improved the shape memory recovery time of composites.With the increase of carbon fiber content,the shape fixation rate of biomimetic composites decreases,the shape recovery rate increases,and the shape memory recovery time decreases.(4)Based on multi-layer grid structure of the material,based on PLA/PCL-SMP composites matrix,graphene oxide as light conversion agent,the use of 3D printing technology of direct writing successful preparation of the bionic light space selective shape memory materials,it has dual excitation response,light and temperature at the same time,under the near-infrared light response,excellent optical response shape memory properties,shape fixed rate is as high as 95%,shape recovery rate was 93%,the fastest shape recovery time of 5 s.(5)The bionic optical response cladding release device is designed and fabricated by using bionic optical drive shape memory composite material,which can release the cladding on demand,and display excellent remote control,rapid response,accurate selection and other functional characteristics.