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

• Two novel blue fluorescent polymeric dyes with narrow FWHM were prepared.
• The polymers are totally soluble in common organic solvents and P(3ADQ) is also soluble in aqueous mixture.
• The complete amorphous polymers have excellent thermal stability.
• The photoluminescence of 3MADQ and P(3ADQ) has remarkable sensitivity to pH.

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 Mn = 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 (Tg (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 (CIEx,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 pKa for the alkalescent 3MADQ and P(3ADQ) calculated was 2.4 and 2.7, respectively. Both polymers have similar band-gap energy (Eg) 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 (μhole) of the two polymers were measured to be 4.0 × 10−7 and 10−8 cm2/(V-s) for P(2ADN) and P(3ADQ), respectively.

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