Study On Synthesis And Performance Of Hyperbranched Polysiloxane

It is reported that the globe suffers direct economic losses as high as$700 billion each year from metal corrosion.Therefore,the metal anticorrosion studies hava gained widespread attention.Metal corrosion is caused by surface concact with the surrounding medium via chemical or electrochemical reaction.At present,protection coating technology is the most effective and most common means of preventing the occurrence of metal corrosion,the affect of coating protection mainly includes the following three aspects:shielding effect,slow-release effect and cathodic protection.Traditional organic coatings,such as epoxy resin is limited the poor state of light fastness and weather resistance;acrylic resin suffers from low hardness and poor solvent resistance.Ordinary siloxane coating is given priority to with Si-O-Si chains,has excellent thermal stability,corrosion resistance,transparency,and durability.Nevertheless,it takes too high temperature and long time to cure,the thickness of siloxane coating is too thin to generate pores,cracks and low crosslinking area,which will lead to metal incorrsion for inferior shielding effect.Hyperbranched polysiloxane as potential anticorrosion coating,a kind of polymer possesses high liquidity,low viscosity,high heat resistance and carry a lot of modifiable end groups,its highly branched net structure can avoid problems caused by thin thickness,and has plenty of excellent performance,such as non-toxic environmental security,easy to coating,high heat resistance.In this paper,hyperbranched polysiloxane was prepared by transesterification.Then,polysiloxane and graphene oxide were introduced in the coating system.Through a series of characterization methods,the coating properties of the coating,anticorrosion performance and thermal stability were discussed,the main contents are as follows:(1)Hyperbranched polysiloxane coatings was synthesize through transesterification.The structure and properties of hyperbranched polysiloxane coating via different mole ratio of acetic anhydride/monomer A were researched through the FI-IR,~1H-NMR,MALDI-TOF,TGA and electrochemical workstation.when the molar ratio of acetic anhydride/monomer A is 1.5,the coatings have the best thermal stability and corrosion resistance.(2)HBPSi-PDM coatings were prepared by hydrosilylation.The influence of two kink polymer proportion on the structure and performance of coatings by means of FI-IR,SEM-EDS,TGA,fog tests and electrochemical workstation,and the curing mechanism of coating and corrosion mechanism were discussed.The results showed the introduction of polysiloxane improved the coating hardness,shortened the curing time.When elevated the hydrogen content of polysiloxane,thermal stability has improved,figures from the EIS suggested its impedance value raised at first,then decreased,when hydrogen content was 0.4%,attained the maximum impedance values.When the molar ratio of Vi/S-H equals 2,the coating possessed the best anti-corrosion performance.(3)The HBPSi-PDM-SGO coatings were compounded through adulterating GO modified by APS to HBPSi-PDM coatings.Effects of modified GO on the properties of composite coating were discussed via TGA,DSC,electrochemical workstation.The results implied that graphene oxide improved the thermal stability and anti-corrosive performance of the coatings,shortened curing time,increase the coatings'hardness.In conclusion,this paper claimed hyperbranched polysiloxane was prepared successfully,and constructed HBPSi-PDM-SGO coatings system through different ways on grafting polysiloxane and graphene oxide on HBPSi coatings,at the same time,curing mechanism and anticorrosion mechanism of coating was discussed.The problems of thin thickness and high curing temperature have been solved,make it has a broad application prospect in the field of coating.