Coated hollow and evacuated insulation spheres (CEIS)

A method of making an insulation medium, comprising the steps of:

• providing a plurality of microspheres, each microsphere comprising a porous core comprising a porous core material and having an exterior surface;
• positioning a gas within the porous core;
• applying a coating layer covering all of the exterior surface of the porous core to provide a coated porous core, wherein the coating layer comprises a coating material which transitions from a first state to a second state, and wherein in the first state the coating material is permeable to the gas, and in the second state the material is impermeable to the gas;
• applying a vacuum to the coated porous core, wherein some of the gas will diffuse through the coating material in the first state to establish a partial vacuum of the gas within the porous core;
• transitioning the coating material from the first state to the second state while maintaining the partial vacuum of the gas within the porous core, wherein the coating in the second state will seal the porous core with the partial vacuum of the gas inside.