Electrospraying the Triblock Copolymer SEBS: The Effect of Solvent System and the Embedding of Quantum Dots

This work reports on ABA triblock copolymer microparticles encoded with CdSe/CdS core-shell quantum dots (QDs) realized by electrospraying. This method allows for simple but efficient embedding of QDs in polymer beads while retaining the fluorescent properties of the original QDs. The creation of poly(styrene-ethylene-butylene-styrene) (SEBS) monodisperse spherical microparticles with a tunable morphology for applications of the final QD-loaded product is attainable via solvent variation. By varying the selectivity of the solvent for one of the distinct blocks in the polymer, the final particle morphology can be selectively altered while maintaining the same overall process conditions, allowing to tailor the particles from homogeneously flat in a nonselective solvent to dense spherical particles in an endblock selective solvent system. The mechanism responsible for this transition in morphology can be related to differences in mass transfer in the droplets and thus solvent evaporation rates arising from particular microphase structures. Finally, fluorescence characteristics of the final QD-embedded polymer particles and photodegradation stability are investigated by spectrophotometry and are compared to the temporal evolution of the original QDs, indicating significant stability improvement and well-dispersed QDs in an optimized polymer matrix morphology.