Polystyrene (PS) and its copolymers, including those crosslinked with divinylbenzene (DVB), are primarily known for their UV-blue luminescence, typically emitting in the range of 280-350 nm when excited with UV light. This luminescence is primarily due to the π-π* transitions of the aromatic styrene units.

Regarding the emission around 510 nm, which falls into the green region of the spectrum, there is no direct evidence in the literature suggesting that pure PS or PS-DVB can emit at this wavelength under normal conditions. However, the possibility of green emission due to structural defects or specific crosslinking scenarios with DVB cannot be entirely dismissed without further investigation.

Structural defects, such as chain branching, unsaturation, and other irregularities in the polymer backbone, can influence the electronic properties of the polymer. These defects might create localized states in the electronic structure of the polymer, potentially leading to emissions at longer wavelengths. Similarly, the crosslinking introduced by DVB can alter the electronic environment of the polymer chains. The extent and nature of crosslinking could affect the conjugation length and the rigidity of the polymer network, possibly resulting in altered emission characteristics.

To conclusively determine if PS-DVB can exhibit luminescence around 510 nm, detailed spectroscopic studies focusing on the structure-emission relationship would be required. Techniques such as photoluminescence spectroscopy under various excitation wavelengths, combined with structural analysis methods like FTIR or NMR, could elucidate the influence of structural defects and crosslinking on the luminescence properties. Additionally, computational modeling could provide insights into the electronic transitions and the possible effects of defects and crosslinking on the emission spectrum.

In summary, while the typical emission of PS-DVB is in the UV-blue region, the potential for green emission due to structural defects or DVB crosslinking warrants further investigation through experimental and theoretical studies.

Polystyrene would not be expected to show fluorescence at 510. Polystyrene shows two emissions: monomer emission at 285 nm and excimer at 332 nm. The relative ratios are concentration dependent.

We explored this thoroughly in our 2007 paper

https://doi.org/10.1002/app.24796

However, the prep you cite also includes polyvinylpyrrolidone - which is known to have some emission at wavelengths as high as 510, although the maximum is at 375 nm.

I recommend running an excitation spectrum from 200 to 480 or so with detection at 510 - this will give you the absorbance spectrum of the emitting species.

Because fluorescence is very sensitive, it is very easy to detect fluorescence of trace impurities.