Preparation And Properties Of Electrothermal Dual-response Shape Memory Polylactic Acid/Polyurethane/Silver Nanowire Composite Film

In recent years,with the development of aerospace,medical,electronics and other fields,polymer shape memory materials?SMP?based on bio-based materials have gradually been favored by researchers.Due to the wide variety of SMP,easy processing,and excellent shape memory performance,it has become one of the important research fields at present.In addition to the traditional thermal response of SMP,polymer shape memory composite materials that respond to electricity,light and magnetism are also gradually appearing in people's field of vision.At the same time,in order to promote the development of polymer shape memory materials,the main research direction is to obtain SMP with multi-response and excellent shape memory performance.New methods of preparation are simple,easy to obtain raw materials,high in production efficiency,and convenient in product performance adjustment.Emerge.In this thesis,a spin-coated assembly method was used to prepare a heat-responsive shape memory composite film with a sandwich structure composed of polylactic acid?PLLA?and thermoplastic polyurethane elastomer?TPU?.The prepared film has excellent transparency.The UV-V is spectrophotometer test shows that the light transmittance can reach up to 98%.Scanning electron microscopy?SEM?was used to characterize the microstructure of the assembled film,and it was found that the material has a typical layer-by-layer bi-continuous structure.The interface compatibility between the PLLA and TPU phases is relatively good,ensuring the material's excellent shape memory performance.Through the dynamic thermomechanical analyzer?DMA?on the assembled P/T/P and T/P/T?P stands for PLLA,T stands for TPU?shape memory performance test found that the structure of T/P/T The film has better shape recovery performance.In addition,we investigated the shape memory properties of the five-layer T/P/T/P/T and seven-layer T/P/T/P/T/P/T films,and found that with the increase of the number of alternating layers of the film The shape fixation rate of the material increases while the shape recovery rate decreases.In order to give the above-mentioned assembled film electrical response shape memory properties to expand its application range,we selected silver nanowires?AgNW?with excellent electrical conductivity,high aspect ratio and flexural resistance as conductive fillers and PLLA/TPU assembled films Recombination to achieve the electrical response shape memory behavior of the assembled film.Among them,the synthesis of AgNW adopts the relatively mature polyol method,with ethylene glycol?EG?as the reducing agent,polyvinylpyrrolidone?PVP?as the blocking agent,silver nitrate?AgNO₃?as the silver source,and chloroplatin hexahydrate Acid?H₂PtCl₆?6H₂O?as a nucleating agent successfully synthesized AgNW under nitrogen atmosphere.By adjusting the ratio of PVP and AgNO₃ and the drop acceleration of the mixed solution of PVP and AgNO₃,the influence of different process conditions on the morphology of AgNW was discussed.Finally,AgNW with an aspect ratio of about 800 was prepared with a diameter of 60-90 nm and a length of 30-50?m.The template transfer method and spin-coating assembly were used to successfully composite AgNW onto the surface of the T/P/T sandwich structure film.As the number of AgNW deposited layers increases,the electrical conductivity of the composite film gradually improves.As the applied voltage increases,the rate of electrical heat generation of the composite film increases.By characterizing the electrical response shape memory performance of the composite film,the film can be restored to its original shape in 2.9 s at a voltage of 3 V.In this paper,an electrothermal dual-responsive shape memory film with a layer-by-layer structure is prepared by combining spin coating assembly and template transfer,which greatly expands its application in the field of shape memory materials.