| Implantable medical devices have been a major research hotspot in the field of biomedical engineering,as they can help doctors and patients understand disease information and restore patients’body functions.With the continuous advancement of medical science and the rapid development of electronic information technology,biodegradable medical devices are receiving more and more attention.These medical devices are used in the treatment of diseases,and are then gradually dissolved,digested and absorbed before being excreted.The biodegradable medical devices not only retain the diagnostic functions of traditional medical devices,but also avoid the need for surgical removal of the device and reduce the risk of long-term inflammation.In order to drive such devices properly,biodegradable power sources capable of stable operation are required.Implantable degradable electrode materials reported in recent years are mainly classified into biocompatible absorbable metals,redox natural biomolecules and synthetic redox polymers;however,they have their own advantages and shortcomings in terms of biocompatibility and electrochemical properties.However,due to the complexity of the requirements for implantable energy storage materials,it is difficult to combine the conductivity,biodegradability and electrochemical properties of current conductive polymers at the same time.More importantly,the design and synthesis of conductive polymeric energy storage materials for implantable battery applications is still lacking.Based on this,the aim of this thesis is to design and synthesise a class of fully degradable conductive polymer electrode materials for use in implantable biodegradable zinc batteries.This thesis proposes a molecular design concept that uses progressively hydrolysable carboxyl functional groups as side chains of the polymer,which retains the pseudocapacitive energy storage properties of poly（3,4-ethylenedioxythiophene）（PEDOT）as the main conjugated chain,while at the same time This design preserves the pseudocapacitive energy storage properties of the poly（3,4-ethylenedioxythiophene）（PEDOT）as a conjugated backbone,while at the same time providing the polymer with regulated total degradability.Specifically,in this thesis,a biocompatible and fully degradable PEDOT derivative was synthesized by molecular design engineering by introducing carboxyl functional groups of different carbon chain lengths into the polymer side chains.This molecular design combines the pseudocapacitive charge storage of the conjugated backbone with the hydrolysable carboxyl side chains,and the polymer exhibits p H-dependent fully degradable behavior in aqueous solution,resulting in a tunable degradation performance.The polymer was assembled as a cathode,the bioresorbable zinc sheet as an anode and the gelatin-based gel electrolyte to form an implantable rechargeable zinc battery;the battery provides a specific capacity of 31.8 m Ah g-1（57%of the theoretical capacity）and excellent cycling stability(78%capacity retention over 4000 cycles at 0.5 A g-1).The molecular structure of the polymer at different voltages was characterized using non-in situ XPS,Raman,to elucidate the energy storage mechanism of the polymer electrode in the zinc cell.Next we used polyvinyl alcohol films as encapsulation material and the assembled zinc cells could be fully degraded after 30 days in phosphate buffer solution.This zinc cell was implanted subcutaneously in Sprague-Dawley rats and showed complete biodegradability and biocompatibility.The non-toxicity of the degradation products of the zinc battery was confirmed by section staining tests of various organs.In summary,this thesis synthesizes an implantable fully degradable polymeric energy storage material that significantly improves the performance of implantable batteries and may also extend their application in environmentally friendly and renewable electrochemical energy applications,providing a research base for the development of implantable medical electronics. |
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