A fiber of linear polymer coated with a siloxane-carborane polymer or a thermoset or ceramic made therefrom. An organic fiber coated with a siloxane-carborane polymer or a thermoset or ceramic made therefrom and a surfactant. An organic fiber coated with a siloxane-carborane polymer made from a hydrosilation reaction of a siloxane-carborane compound containing at least two unsaturated carbon-carbon bonds and a silane compound or a thermoset or ceramic made therefrom. A method of coating a fiber by contacting a fiber to an aqueous solution of a siloxane-carborane polymer and a surfactant or to a solution of a siloxane-carborane polymer in a non-halogenated organic solvent. A method of contacting a fiber to a solution of a siloxane-carborane polymer, drying the coating to a temperature that does not change the polymer to a thermoset or ceramic, and using the dried, coated fiber in a process that requires that the fiber be flexible.