FIG. 6A is a dark field microscopic image of silica capsule dispersion in water and FIG. 6B is a dark field microscopic image of hetero-coagulated silica capsules with poly-NIPAM latex particles prepared from a method in accordance with an example embodiment disclosed herein. The scale bar in both figures represents 50 pm. FIG. 7 is a graph showing the particle size distribution of a silica capsule obtained after heterocoagulation. FIG. 8A is a thermogravimetric analysis (TGA) graph of silica capsules and FIG. 8B is a thermogravimetric analysis (TGA) graph of hetero-coagulated silica capsules with poly-NIPAM latex particles prepared from a method in accordance with an example embodiment disclosed herein. FIGS. 9A-9C are scanning electron microscopy (SEM) images of sub-20 micron silica capsules stabilised by cetyltrimethylammonium bromide (CTAB) in accordance with an example embodiment disclosed herein, taken at various stages of polymer coating. These images are captured after 2-3 hours after heterocoagulation and film formation under SEM conditions. FIG. 9A shows an SEM image taken at 5,000x magnification, with the scale bar representing 1 pm. FIG. 9B shows an SEM image taken at 5,000x magnification, with the scale bar representing 1 pm. FIG. 9C shows an SEM image taken at 1,000x magnification, with the scale bar representing 10 pm. FIG. 10A is a scanning electron microscopy (SEM) image of original silica capsules and FIG. 10B is a scanning electron microscopy (SEM) of polycaprolactone particles coated on silica capsules after hetero-coagulation in accordance with an example embodiment disclosed herein. FIG. 10A shows an SEM image taken at 1,000x magnification, with the scale bar representing 10 pm. FIG. 10B shows an SEM image taken at 2,000x magnification, with the scale bar representing 10 pm.