Stoichiometric complexes of hyaluronic acid with alkyltrimethylammonium surfactants bearing octadecyl, eicosyl and docosyl groups were prepared by ionic coupling in aqueous solution. The complexes were non soluble in water but soluble in organic solvents. In the solid state they self-assembled in a biphasic layered structure with the alkyl side chains forming a separate phase that melted in the 50–60 °C range. They were stable to heating up to above 200 °C.
Tolentino, A. [et al.]. Comb-like ionic complexes of hyaluronic acid with alkyltrimethylammonium surfactants. "Carbohydrate polymers", 30 Gener 2013, vol. 92, núm. 1, p. 691-696.