Preparation And Properties Of Cross-linked Polyisocyanate Derivative

Isocyanide has good polymerization activity,and can be polymerized with the catalysts of some transition metals(such as nickel,palladium and rhodium etc.)to form the corresponding polyisocyanides.From the current report,we can see that the research regarding polyisocyanides mainly focuses on the preparation and application of linear polyisocyanides(using monofunctional isocyanide as the starting monomer).However,the utilization of multifunctional isocyanides to prepare polyisocyanides,which with cross-linked configurations has not been reported yet.Besides,according to literatures,the complex containing Schiff base substructure has been proved to possesses the potential of NO2electrochemical probing.Therefore,the research about the polyisocyanide,which containing Schiff base motif in its structures,for NO2-detection with a certain research space and worth to be investigated.On the other hand,nitrogen-doped carbon materials have been widely used in supercapacitors as energy storage materials.Using the cross-linked polyisocyanide,which with a primary pore structure as a nitrogen-containing carbonization precursor,it is expected that a new type of N-doped carbon material can be prepared for subsequent application in the energy storage field through subsequent sintering treatment.Taking the preparation of cross-linked polyisocyanide and subsequent application research as the starting point,the work of this article mainly includes the following parts:1.With 4,4’-diaminodiphenylmethane as the starting material,a bifunctional isocyanide compound(M1)based on diphenylmethane skeleton was successfully prepared by Hofmann reaction,and a polyisocyanide(P1),which with cross-linked structure,was successfully prepared under nickel catalysis.Through catalyst screening experiments,it was determined that bis(diphenylphosphine)ethane nickel chloride(Ni(dppe)Cl2)(with 4%catalyst dosage)was determined as the optimal experimental condition,and the chemical structure and micro morphology of the obtained polymer were characterized here.The P1 modified glassy carbon electrode(P1/CS/GCE)was used as the working electrode to successfully realize the electrochemical detection of NO2-,and the corresponding detection limit was 0.51 μM(3σ/k).The experimental results show that P1 is a potential NO2-probing material;2.With biphenyldiamine as a starting material,an isocyanide compound(M2)based on biphenyl skeleton was prepared by Hofmann reaction,and a cross-linked polyisocyanide compound(P2-1)was successfully prepared under the catalysis of Ni(dppe)Cl2 with high yield(95%),and its chemical structure was characterized here.The feasibility of the preparation process of cross-linked polyisocyanide and the universality of monomer substrates were verified thus.Using the P2-1 modified glassy carbon electrode(P2-1/CS/GCE)as the working electrode also realized the electrochemical detection of NO2-,and the corresponding detection limit was 0.47 μM(3σ/k).This indicates that P2-1 is also a potential NO2-probing material,which verified the application prospects of polyisocyanide compounds in the field of NO2-electrochemical sensing once again;3.Nitrogen-doped porous carbon material(Pl-C)was successfully prepared by direct carbonization of the prepared polyisocyanide P1,which has a suitable pore size distribution and specific surface area(648.28 m2 g-1).Under the three-electrode system(with 6 M KOH as the electrolyte),the specific capacitance reached 152.5 F g-1 when the current density is 0.5 A g-1,and the specific capacitance remains 94.4%of its original value after 1000 charges and discharges cycles.The energy density of the symmetric supercapacitor,which with P1-C as the active material,reached 3.44 Wh kg-1 when the power density is 100 W kg-1,and also showed good cycling stability.