Research On Polymer Brush-assisted Liquid Metal Micropattern Preparation And Applicatio

In recent years,liquid metal has become an ideal material for the preparation of flexible sensors of its excellent conductivity,super plasticity and good biocompatibility.The patterning of liquid metal is the prerequisite for its application in flexible sensors.At present,the methods used for patterning of liquid metal mainly include direct writing printing method,microchannel injection method,screen/template printing method,etc.However,the above methods have problems such as poor preparation pattern accuracy and stability,complex preparation process and high cost,which hinder their application in the preparation of liquid metal clusters.Therefore,it is a very important and challenging research work to carry out research and technological innovation on the preparation methods of liquid metal micropatterns.In this paper,a method of using polymer brush patterned surface as a template to assist metal selective deposition and then induce liquid metal adhesion to prepare liquid metal micropatterns was proposed.Based on the Digital Micro-mirror Device（DMD）,the polymer brush pattern was prepared by the atomic transfer radical polymerization（ATRP）reaction induced by light irradiation.The effect of reaction conditions on the growth of polymer brush was studied.Copper was deposited on the surface of the polymer brush by polymer brush assisted metal non-electrodeposition to prepare copper pattern.In the dilute hydrochloric acid environment,the liquid metal is adhered to the copper surface to form a liquid metal micro-pattern and applied research.The polymer brush was prepared on the surface of the flexible substrate by surface ATRP initiated by DMD light regulation and assisted copper deposition to prepare liquid metal micropatterns.The main research contents and results are as follows:（1）First,the initiator as the middle layer of the reaction was grafted onto the surface of the silicon substrate by virtue of the super adhesion and chemical reactivity of polydopamine.Then,methacryloyloxyethyl trimethyl ammonium chloride（METAC）was used as the polymerization monomer.The PMETAC polymer brush pattern was prepared by digital micromirror device（DMD）,which controlled light irradiation selectivity and induced ATRP reaction.The results of XPS and optical microscopy showed that the PMETAC brush was successfully prepared.By preparing PMETAC patterns of different sizes and shapes and PMETAC brush patterns of irregular patterns,The results show that the PMETAC brush pattern prepared by this method has good applicability and accuracy.（2）Using the patterned surface of the ionic PMETAC brush as a template.The metal catalyst was fixed on the molecular chain of the PMETAC brush to induce copper deposition through the ion exchange between the positive quaternary ammonium group at the end of the PMETAC brush and the active ion[Pd Cl₄]^2-.The results of optical microscopy and XPS tests showed that copper was selectively deposited in the PMETAC brush region,and the electrical properties of copper patterns with different sizes were investigated.The experiment of connecting the wire through the copper pattern on the surface of the silicon wafer to light the light-emitting diode was designed,The results show that the copper pattern prepared by this method has excellent conductivity.（3）The adhesion experiments of copper film to liquid metal on different substrates and in different reaction environments were designed.The results showed that liquid metal could adhere to copper film in dilute hydrochloric acid environment.The experimental results of 45°tilt showed that the liquid metal has strong adhesion after alloying with copper film.Liquid metal micropatterns are prepared by adhering liquid metal to copper patterns in dilute hydrochloric acid environment.Five different shapes of liquid metal micro-patterns were designed.The results of optical microscope showed that the liquid metal patterning method had certain accuracy.Five different sizes of liquid metal wires were designed.The resistance measurement results showed that the wider the circuit wire,the smaller the resistance.Finally,the circuit pattern was designed to light up the light emitting diode to explore the application of liquid metal pattern in circuit preparation.（4）The flexible substrate of PDMS was prepared,and the mechanical properties of PDMS prepolymer and curing agent in different proportions were studied.The initiator functionalization of PDMS flexible substrate surface was realized by polydopamine.PMETAC brush patterns with different shapes and sizes were successfully prepared on PDMS surface by surface ATRP reaction initiated by DMD light regulation.The copper pattern was prepared on the surface of PDMS by PMETAC brush assisted metal non-electrodeposition.The adhesion of liquid metal on the surface of copper pattern was realized by alloying reaction between liquid metal and copper in dilute hydrochloric acid environment,and then the liquid metal patterning on the surface of PDMS flexible substrate was realized.