Study On Properties And Application Of Bilayer Stimuli-responsive Film Prepared By Electrospinning

Stimuli-responsive materials,as the fourth generation materials after natural materials,synthetic polymer materials,and artificially designed materials,can undergo shape change or motions under external physical or chemical stimuli(light,electricity,magnetic field,temperature,humidity,p H,organic solvents),which can be widely used in the fields of sensors,actuators,energy harvesting devices,soft robots,mechanical arm.Up to now,many properties of the stimuli-responsive materials such as shape deformation amplitude,actuation speed and programmable deformation have been greatly improved.In addition to these properties,there are still challenges in preparing smart films with multiple responses and multifunctionality.In this study,two smart composite membranes were prepared by the electrospinning process.One was a smart film with multi-functional solvent responsiveness;the other was a acetone/ humidity dual-response composite film.The detailed process of this research was briefly described as follows:(1)Multifunctional PCL/PLLA bilayer fiber membrane was prepared by electrospinning.First,the bilayer membrane exhibited ultrafast actuation speed in response to acetone stimulus(bent into a closed loop in 0.1 s).The influence of film thickness and acetone concentration on the magnitude of deformation was studied.Secondly,oriented PLLA fibers provided the possibility to realize the programmable deformation of the bilayer membrane(twisted,curled,bent).Thirdly,the piezoelectric material PLLA,as a mechanicalelectric conversion layer,could monitor the deformation of the bilayer film in real time in the form of electrical signals.Besides,We have explored the deformation mechanism of the bilayer fiber membrane through a combination of experiment and computation.Finally,We have designed a series of application models including soft robots,robotic arms,bionic flowers and sensors.(2)To solve the single stimulus response problem of smart film,we have prepared an acetone/humidity dual-responsive PCL/PEO bilayer film.We studied the continuous bending deformation of the bilayer fiber membrane under the stimulation of acetone vapor and humidity,and the influence of the thickness of the active layer,the concentration of acetone and the humidity on the deformation amplitude was studied.Finally,We designed a circuit switch controlled by humidity.