Conjugated Polymers Containing Naphthalene Synthesised By Solid-state Oxidative Coupling Reaction And Their Optical Properties

Due to their unique photoelectric properties and their application to optoelectronic devices,conjugated polymers have received much attention.Naphthalene rings are widely used to construct naphthalene conjugated polymers because of their unique structure and multiple reactive sites.In this work,the novel conjugated polymers containing naphthalene were prepared from the naphthalene compounds chosen as the monomers by the solid-state oxidative coupling reaction.The optical properties of the polymers were investigated in detail from the polymer solutions,the polymer/PMMA solid solutions,and the thin films.Firstly,from FT-IR spectrum,1H NMR spectrum,and Huckel charge calculation,we characterized the structures of the poly(alkoxynaphthalene)s as the condensed state structure of 1,4-linked poly(naphthalene)with highly fused aromatic rings.The interesting concentration induced discoloration phenomenon could be observed from the polymer solutions and the polymer/PMMA solid solutions.The ?PL max was shifted from the UV region in the dilute solution to 520 nm,and even shifted to 620 nm when polymer concentration was greater than 0.1 mg mL-1.The properties of concentration-induced fluorescence spectra can still be observed from the polymer/PMMA films.Moreover,the choice of solution and the length of the side-chains can also affect the change in fluorescence properties.In conclusion,the fluorescence properties of poly(alkoxynaphthalene)s are mainly determined by the change of polymer solution concentration,which leads to the increase of the effective conjugated length of polymer backbone and the formation of polymer aggregation.The poly(a-trinaphthylbenzene)s(Pa-TNB)were prepared from C3-symmetric a-trinaphthylbenzene by the solid-state oxidative coupling reaction.The red products were insoluble in most of organic solvents.The introduction of alkoxy side-chains can improve the solubility slightly.The ?PL max of Pa-TNB from the THF solution,the PMMA solid solution,and the thin film red shifted from blue light emission to yellow-green light emission,respectively,which is different to the bright red light observed under the ultraviolet light(365 nm).The bright red light is originated from the polymer itself.Pa-TNB exhibits excellent thermal stability,especially,P3 began to decompose after 550?,and residual carbon rate above 80%after 800 ?.After carbonization,the porous carbon material from P3 can be obtained with the specific surface area of 554.60 cm3 g-1,and it's saturated adsorption capacity of CO2 is 80.85 cm3 g-1 at 273K.The solid-state oxidative coupling reaction of ?-trinaphthylbenzene was discussed.The poly(?-trinaphthylbenzene)s(?-TNB)were orange powder.The ?PL max of P?-TNB in solution was red shifted from UV region of 365 nm to blue-green emission of 483 nm.The fluorescence properties of the P?-TNB/PMMA film and the polymer particles in THF/H2O mixed solution also show the same trend.The change in fluorescence properties of P?-TNB is mainly due to the change in the concentrations,resulting in the change of polymer's conformation and aggregates,which lead to an increase in the effective conjugate length of the polymer backbone.At the same time,the solution of P?-TNB showed certain sensitivity to the fluorescence detection of Fe3+ ions and nitro compounds.