Described herein are all-dry encapsulation methods that enable well-defined polymers to be applied around particles. One aspect of the invention relates to a method of coating a particle, comprising the steps of: placing said particle in a vessel at a pressure; rotating said vessel at a rotating speed for a period of time; mixing together a first gaseous monomer at a first flow rate, and a gaseous initiator at a second flow rate, thereby forming a mixture; introducing said mixture into said vessel via a vapor feedline; heating said mixture, thereby forming a reactive mixture; contacting said particle with said reactive mixture; thereby forming a polymer coating on said particle. The methods may be modified forms of initiated chemical vapor deposition using a thermally-initiated radical polymerization to create conformal coatings around individual particles while avoiding agglomeration. Particle surfaces may be coated with a range of functional groups.