Robust, Low Permeability, Water-Filled Microcapsules

The Navy is actively developing a self-sealing, water-activated fuel bladder to mitigate fuel leaks upon mechanical shock (e.g. penetration by a .50 caliber bullet). To circumvent the requirement of an external water source to activate the self-sealing, this system will require water-filled microcapsules that can be incorporated directly into the polymeric matrix of the fuel bladder. Upon mechanical shock, the capsules will rupture and release water to initiate the self-sealing mechanism; however, currently available water-filled microcapsules can contain water only for days to weeks before the water permeates the microcapsule shell. There is a need to develop robust water-filled microcapsules that exhibit low to zero water permeability for 20 years, thermal stability from -40°F to 135°F, and mechanical robustness to prevent premature rupture of the capsules during processing in viscous pre-polymer liquids. Scientists at Luna Innovations, in partnership with the Southwest Research Institute (SwRI), have developed an encapsulation approach that will provide excellent water barrier properties, mechanical durability, and monodisperse size control. This technology will enable the development of robust, thermally stable, and water-impermeable microcapsules that meet the stringent requirements of the Navy.