Preparation And Properties Of Polymer Composites Based On G-C₃N₄

With the development of the industry,and the science and technology,the high molecular polymer materials are widely used in life and production.The traditional high-molecular polymer materials are of a single type and have structural defects resulting in poor performance in some areas,so they are easily limited in practical applications.Polymer/inorganic nanocomposites,which combine the strength,flame retardancy,and abrasion resistance of inorganic materials with the elasticity,ductility,and conductivity of polymers,are attracting the attention of people and are bound to become one of the hot topics in the field of materials in the future.Graphite carbon nitride(g-C3N4)is a two-dimensional sheet material with yellow appearance and a similar structure to the graphite.Graphite carbon nitride has thermal stability,chemical stability,photocatalytic performance and fluorescence properties.It can be prepared by simple methods,and its raw materials are abundant.So graphite carbon nitride will have more advantages than carbon materials in practical applications,such as be used in the photocatalytic reaction,as fluorescent probes and flame-retardant composites.In this paper,the preparation of graphite carbon nitride was studied.After peeling off graphite carbon nitride to graphite carbon nitride nanosheets,the composite materials were prepared with polyacrylamide/polyacrylic acid or polyvinyl alcohol.The structures and properties of the composite materials were analyzed.The detailed work can be summarized as following:1)Using melamine hydrochloride and melamine as precursors,porous graphite carbon nitride and bulk graphite carbon nitride were prepared by heat-shrinking polymerization.The structure of porous graphitic carbon nitride is similar to bulk graphite carbon nitride.The porous graphitic carbon nitride has a loose porous layered stack structure with a larger specific surface area to do better photocatalytic activity than bulk graphite carbon nitride.2)The graphite carbon nitride nanosheets(CNNS)was prepared by ultrasonic exfoliation of bulk graphite carbon nitride.Then,a series of CNNS/PAM/PAA hydrogels with different content of graphite carbon nitride nanosheets were prepared by free radical polymerization with the materials such as acrylamide(AM),acrylic acid(AA),ammonium persulfate(APS),N,N-me thy lenebis acrylamide(BIS)and graphite carbon nitride nanosheets.Compared with PAM/PAA hydrogel,the addition of CNNS can increase the salt tolerance of the composite hydrogel.In different pH buffer solutions,the composite hydrogels still maintain the pH sensitivity to the aqueous solutions.At the same time,CNNS/PAM/PAA hydrogels can be used as fluorescent probes for detecting silver ions because CNNS/PAM/PAA hydrogels have good fluorescence properties and high selectivity to silver ions.3)The graphite carbon nitride nanosheets(g-CNs)was prepared by chemically exfoliation of bulk graphite carbon nitride.Then the g-CNs/PVA films were prepared by solution blending with polyvinyl alcohol and graphite carbon nitride nanosheets.By the studies on their chemical,mechanical,thermodynamic,and optical properties,we found that graphite carbon nitride nanosheets of lower levels are uniformly dispersed in the composite membrane and there were no agglomeration.And the introduction of graphite carbon nitride nanosheets improved the mechanical and thermal properties of the composite membranes and made the composite membranes have photoluminescent properties.