Synthesis and characterization of highly soluble blue emitting poly(2-vinylanthracene) with 9,10-di(2-naphthalenyl) and 9,10-di(3-quinolinyl) substituents

Abstract Two new blue fluorescent polymers, poly(9,10-di(2-naphthalenyl)-2-vinylanthracene) ( P(2ADN) ) and poly(9,10-di(3-quinolinyl)-2-vinylanthracene) ( P(3ADQ) ), were polymerized from free radical solution addition polymerization with M n  = 21,500 and 15,400, respectively. The polymers are highly soluble in common organic solvents while P(3ADQ) is also soluble in polar solvents including a 1/1 mixture of ethanol/water. Both polymers are amorphous with excellent thermal stability ( T g (Midpoint) = 343 °C and 298 °C for P(2ADN) and P(3ADQ) , respectively). P(2ADN) exhibited three prominent absorption bands in tetrahydrofuran (364, 383 and 403 nm) and is similar to that of P(3ADQ) (369, 384 and 404 nm). The solid-state Commission Internationale d’Eclairage (CIE x , y ) color coordinates for illumination were (0.15, 0.10) for P(2ADN) and (0.15, 0.13) for P(3ADQ) which lied within the requirements for a true blue display color. The photoluminescence (PL) of the polymers red-shifted 16–17 nm from their respective pendant chromophore 2-methyl-9,10-di(2-naphthalenyl)anthracene ( 2MADN ) and 2-methyl-9,10-di(3-quinolinyl)anthracene ( 3MADQ ) and can be attributed to partial π–π stacking between the adjacent aromatic pendant groups in the polymer chains. The luminescences of 3MADQ and P(3ADQ) are sensitive to pH and the p K a for the alkalescent 3MADQ and P(3ADQ) calculated was 2.4 and 2.7, respectively. Both polymers have similar band-gap energy ( E g ) between 2.88 and 2.91 eV, while the LUMO/HOMO for P(3ADQ) is shifted slightly downward −0.06 to −0.03 eV compared to P(2ADN) . The mobility ( μ hole ) of the two polymers were measured to be 4.0 × 10 −7 and 10 −8  cm 2 /(V-s) for P(2ADN) and P(3ADQ) , respectively.