The use of poly(1-methylpyrrol-2-ylsquaraine) particles as a sacrificial template for the preparation of core-shell materials

Sixty-four elements from the periodic table, mainly in the form of metal oxides or chloride/sulfate salts dissolved in either HCl or H2SO4, have been adsorbed into tetraethyl orthosilicate treated poly(1-methylpyrrol-2-ylsquaraine) particles and then heat treated to remove the polysquaraine core to produce core-shell materials. Powder X-ray diffraction techniques were utilised as the primary means of identification for each inorganic compound/mixture inside the amorphous silica shells. In twelve cases (B, Al, Ca, Ti, Ga, As, Se, Mo, Sb, Os, Hg, and Tl) no crystalline material was identified within the shells but analysis of these sample powders (except B) using X-ray fluorescence techniques identified the presence of all bar three elements (Ga, Se, and Hg). The colour of each resultant powder has been reported and in several cases indicated the creation of new physical characteristics. The process was shown to also work with a selected mixture of starting materials with the production of 2% Eu doped YVO4 inside the silica shells. Further results have been presented for the previously published Fe2O3 core – SiO2 shell sample plus additional electron microscopic analysis of the Ag core - SiO2 shell and Au core - SiO2 shell samples. This paper demonstrates a proof-of-concept methodology for the production of new core-shell materials. [Display omitted] •Core-shell materials made from sixty-four elements of the periodic table.•Poly(1-methylpyrrol-2-ylsquaraine) particles used as sacrificial templates.•Crystalline core compounds identified using powder XRD techniques.•Nine core compounds were amorphous; three core compounds decomposed.•Physical characteristics of several core compounds differ inside silica shells.