A cured polycyanurate, thermoset resins, and methods of producing the same that will have both high thermal resistance as well as high hydrophobicity. Naturally occurring 5-alkylresorcinols and synthetic analogs can be made into cyanate ester. Composites made from these products will have greater durability against atmospheric water exposure. Applications include use in fiber-reinforced composite materials for lightweight, strong, and water-resistant aerospace components.