Abstract: The invention provides materials and methods for forming coatings on substrates. The coatings are durable and resistant to damage from environmental, chemical, thermal, and/or radiative sources. In some embodiments, the coatings comprise bilayers of electrostatically charged materials. The bilayers are created by alternately applying solutions comprising water-soluble, electrostatically charged materials. Durability is imparted to the coatings by the formation of crosslinks that are formed within and between layers after deposition of the coatings.