Synthesis and characterization of poly(1,5-naphthylene vinylene) and its copolymers with poly(2-methoxy-5-(2′-ethylhexyloxy)-p-phenylene vinylene)

Poly(1,5-naphthylene vinylene) (PNV) and its copolymers with poly(2-methoxy-5-(2′-ethylhexyloxy)-p-phenylenevinylene) (MEH-PPV) were synthesized via a liquid-solid two-phase reaction. The liquid phase was a tetrahydrofuran (THF) solution of the monomers, 1,4-bis(bromomethyl)-2-methoxy-5-(2-ethylhexyloxy)benzene (MOEHODCX) and 1,5-bis(bromomethyl) naphthalene (DBMN), and contained a certain amount of tetrabutylammonium bromide (TBAB) as a phase transfer catalyst. The solid phase was potassium hydroxide particles with diameters smaller than 2 mm. The structures of the polymers were studied by infrared and Raman spectroscopies. The solutions of the copolymers emitted green light. The UV-vis and photoluminescence spectral bands of the copolymers showed blue shifts with the increase in their PNV contents. A polymer light-emitting diode was fabricated with the copolymer prepared by copolymerization MOEHODCX and DBMN with feeding molar ratio of 1:1, and its luminescence efficiency was measured to be 0.069.