The current invention provides a novel method to synthesize a mono-disperse non-porous polymer particles with a unique gradient composition from the core to the shell. In particular, the present invention offers the flexibility to design the chemical and physical properties of different sections of the particle. This flexibility allows for significant latitude in the design of particles for analyzing a large variety of samples in different fields—through using these particles in different chromatography techniques including, but not limited to, ion exchange HPLC (e.g., bio-separation at different modes), reversed-phase HPLC, narrow bore and capillary HPLC, hydrophilic/hydrophobic interaction liquid chromatography, capillary electrochromatography separation, and two dimensional liquid chromatography.