Bi- and trifunctional periodic mesoporous organosilicas (PMOs) with phenylene, thiophene, and ethane bridging groups were synthesized using 1,2-bis(triethoxysilyl)ethane (BTEE), 1,4-bis(triethoxysilyl)benzene (BTEB), and 2,5-bis(triethoxysilyl)thiophene (BTET) organosilica precursors and a poly(ethylene oxide)-Poly(D,L-lactic acid-coglycolic acid)-poly(ethylene oxide) (PEO-PLGA-PEO) triblock copolymer template under low acidic conditions. The PMO samples with different concentrations of organic bridging groups were obtained in the form of spherical particles having average diameters of 2-3,urn and 2D hexagonal (p6m) mesostructure with pore diameters of 7.3-8.4 run. The particle morphology and chemistry of pore walls were tailored using different mixtures of organosilica precursors. Adsorption and structural properties of the aforementioned PMOs have been studied by nitrogen adsorption and small-angle X-ray scattering, whereas their framework chemistry was quantitatively analyzed by solid-state C-13 and Si-29 MAS NMR.