Synthesis and optical properties of poly[(4-(benzoxazole-2-yl)phenyl)methyl methacrylate] with 1,8-naphthalimide end group

Abstract

A series of homopolymers, poly[(4-(benzoxazole-2-yl)phenyl)methyl methacrylate] (NAPH-PMABEs)containing benzoxazole side chain and 1,8-naphthalimide end group, were prepared by atom transfer radical polymerization (ATRP) and end-group modification. The structure of NAPH-PMABE was characterized by GPC, 1 H-NMR and UV-vis spectra. The polymer has good solubility in common organic solvents, such as dichloromethane (CH 2 Cl 2 ), tetrahydrofuran (THF), N,N-dimethylformamide (DMF), chloroform (CHCl 3 ), acetone and toluene. The optical properties of NAPH-PMABE were investigated. Results show that NAPH-PMABE has a composite emission spectrum comprising an ultraviolet component originating from benzoxazole side chains and a green component originating from 1,8-naphthalimide end group in both solution and film. The intensity of the two emission bands can be easily tuned by changing molecular weight. benzoxazole, 1,8-naphthalimide, emission tuning In recent years, polymers with different optical moieties have attracted much attention due to their applications in sensors [1] , light-emitting diodes [2][3][4] , etc [5,6] . The optical properties of these materials can be easily tuned by controlling contents of different moieties. Though a great deal of excellent work has been reported on such materials [7][8][9] , it is still meaningful to extend the research of these polymers, including different polymerization methods and combination of different moieties.Benzoxazole-containing polymers were used as sensors [10][11][12] , light-emitting diodes [13] and fluorescent pattering [14] due to their good optical properties. The introduction of other optical moieties to these polymers may show some interesting emission tuning, as reported in our previous work [15] . Meanwhile, 1,8-naphthalimide moieties were widely used as emission color-tuning moieties in many systems because of their good fluorescent properties [16][17][18] . However, there have been few reports about the polymers containing both benzoxazole and 1,8-naphthalimide moieties.Atom transfer radical polymerization (ATRP) has attracted considerable attention as a versatile tool to prepare functional polymers [19][20][21][22][23][24][25] , including fluorescent polymers [26][27][28] . In our lab, one of our researches has focused on the design and synthesis of various end-functional or side-chain functional polymers with optical properties such as fluorescence and nonlinear optics via ATRP [29][30][31][32] . Recently, we prepared a di-block copolymer, poly(4-(benzoxazole-2-yl)phenyl) methymethacrlate-bpoly(4-(2-(9-anthryl))-vinyl-styrene) (PMABE-b-PAVS) containing both benzoxazole and anthrancene groups through ATRP. The copolymer shows a composite fluorescent spectrum comprising an ultraviolet component