Facile fabrication and SERS performance of polymer/Ag core-shell microspheres via the reverse breath figure accompanied by in situ reduction

A new facile fabrication process of the polymer/Ag core-shell microspheres is demonstrated via the reverse breath figure method accompanied by in situ reduction. In contrast to traditional approaches, which require the prior preparation of polymer microspheres, the star-shaped polyhedral oligomeric silsesquioxane (POSS) amphiphilic block copolymers solution containing AgNO₃ is cast under ethanol vapor for the formation of polymer/AgNO₃ core-shell microspheres in one step. The influence of polymer molecular structures, solvent, non-solvent and metal salt on the morphology of polymer microspheres was analyzed. Then the AgNO₃ can be reduced in situ to form Ag nanoparticles on the surface of polymer microspheres, which resulted in the formation of polymer/Ag core-shell microspheres. The reduced Ag nanoparticles were homogeneously deposited on the surfaces of polymer microspheres, which can exhibit good performance in the surface-enhanced Raman scattering (SERS). The polymer/Ag core-shell microspheres substrate showed a high detection sensitivity (enhancement factor 2.49 × 10⁶) with excellent uniformity and reproducibility for Rhodamine 6G (R6G) (relative standard deviation of the intensity at 612 cm⁻¹ was 6.19%＜20%). The proposed strategy is facile to implement and thus a promising new method for the preparation of polymer/metal core-shell microspheres.