Study On Curing Mechanism And Properties Of Transition Metals Ions Catalyzed Benzoxazine

Benzoxazine resin has excellent comprehensive properties which makes it widely used in many fields.However,its high curing temperature and brittleness severely restrict its development and application.Therefore,the transition metal nitrate is introduced into the ring-opening polymerization process of benzoxazine resin.While solving the high curing temperature of benzoxazine resin,the in situ introduction of inorganic particles and nitrogen oxide into the benzoxazine system provided a basis for its exploration as a carbon material precursor to prepare carbon materials.The detail research content are in following aspects.?1?Five different metal nitrates?Aluminum Nitrate,Gallium Nitrate,Indium Nitrate,Copper Nitrate and Cobalt Nitrate?were used as catalysts for benzoxazine resins to study its curing behavior and curing mechanism.We found that the addition of metal nitrates indeed catalyzed the curing process of BA-a.All researched metal ion could reduce the curing temperature of BA-a by about 60 ^oC,and followed the change tendency of periodic changes.Secondly,at 35 ^oC,metal ions attack the oxazine ring in the benzoxazine and coordinate with the O atom in the oxazine ring to cause a ring-opening reaction to form a C=N⁺intermediate and a⁺C-N intermediate.The⁺C-N intermediate in the structure participates in the cross-linking reaction of benzoxazine,and cross-linked with other structures to form three cross-linked structures:N,O-acetal Bridge Structure,Arylamine Mannich Bridge Structure and Phenolic Mannich Bridge Structure.And at 35 ^oC,more N,O-acetal bridge structures were formed in the presence of the catalyst and gradually changed to a more stable Arylamine Mannich Bridge Structure.This structural change improves the thermal stability and the toughness of polybenzoxazine.?2?Due to its excellent properties,benzoxazine is an excellent precursor for nitrogen-containing carbon materials.Transition metal nitrate/benzoxazine composite system was used as the precursor of the carbon material,and a ball milling method was used to prepare a precursor of Lithium Iron Phosphate-metal nitrate/benzoxazine carbon material?LFP-M-B?by coating the transition metal nitrate/benzoxazine composite material on the surface of the lithium iron phosphate.It was found that the CV curve of the LFP@M-B showed a rectangular shape compared with the electrode material prepared by@M-B.The carbon material prepared by this method has a more excellent capacitance performance.Meanwhil and the specific capacitance are also greatly improved.?3?Using the Cobalt Nitrate/benzoxazine composite system as the precursor to make carbon material.The ball mill method was used for pretreatment,and then the composite materials were activated at room temperature by KOH one-step activation method to prepare cobalt nitrate/benzoxazine carbon material?@Co-B/OH?.Compared with@Co-B,it has higher crystallinity,larger interlayer spacing,and more chemical reaction sites,which provides a basis for electron transport and ion diffusion.When the carbonization temperature is 750 ^oC,the specific surface area of the activated@Co-B/OH is increased by 142.94 m²/g compared to that of@Co-B and@Co-B/OH.Better capacitance performance,specific capacitance and the improved power/energy density can be got in@Co-B/OH.@Co-B/OH has a enegry density of 0.95 Wh kg^-1 when the power density is 25 W kg^-1.