Research On Designing,preparation And Performance Of Polyester-based Piezoelectric Polymer

With the development of communication network,Internet of Things,and triple play technology,information information interconnection puts forward higher requirements for intelligent sensor devices.Sensors based on piezoelectric materials are intelligent devices that integrate signal sensing and energy harvesting,and are widely used in flexible devices,biomedicine,and environmental power generation.In recent years,polylactic acid-based piezoelectric devices have developed rapidly due to their regenerable,degradable,good biocompatibility,flexibility etc.But their applications have been severely hindered by their low piezoelectric properties.In this work,a novel enhancement mechanism to improve the piezoelectric properties of PLA by reducing the elastic modulus of the material is proposed.A lactic acid-based piezoelectric elastomer with high elasticity,high current density,and self-healing is prepared by random chemical copolymerization.The design mechanism of reducing the elastic modulus of the polymer to increase the degree of deformation,thereby improving the piezoelectric properties of LBPE,is clarified,and the electrical properties,self-healing electrical properties and application fields of LBPE devices are deeply studied.The specific research contents are as follows:（1）LBPE with high-voltage electrical properties and low elastic modulus was prepared by copolymerization of butanediol,lactic acid,sebacic acid,and itaconic acid.Through the introduction of long straight carbon chains（butanediol and sebacic acid）,the mobility of the segments is improved,and the glass transition temperature of piezoelectric polymers is lowered by combining the random copolymerization reaction involving multiple monomers and the introduction of cross-linked networks,which inhibits the crystallization of molecules,reduces the elastic modulus of piezoelectric polymers,and improves their deformability to enhance the piezoelectric properties of LBPE.The elastic modulus of LBPE gradually decreases with the increase of lactic acid content.When the lactic acid molar ratio is 40%,LBPE-40 has a lower elastic modulus and the strongest piezoelectric performance,and its maximum output current density is19.75μA/cm~2,which is 4.21 times the current density of the most mature piezoelectric polymer polyvinylidene fluoride-trifluoroethylene copolymer（PVDF-Tr FE）.（2）The LBPE-40 sample has good self-healing and repairing performance at37°C（human body temperature environment）.After the surface damage is repaired,the electrical output capacity of the LBPE-40 device can recover to 77.38%before the damage.In addition,this work also studies the application of LBPE-40 devices in the fields of mechanical positioning,energy harvesting and sound recognition:in terms of mechanical response,LBPE-40 devices based on arrayed substrates can achieve precise measurement and positioning of stress;In terms of energy generation,the LBPE-40device can realize the collection of energy in human movement,such as finger pressing,palm tapping,and walking and pedaling.In terms of sound recognition,the LBPE-40device can realize accurate measurement of the sound spectrum.The above results show that LBPE-40 piezoelectric devices have potential application feasibility in many fields.