Thiolated polymers  designated thiomers  are functional polymers used in biotechnology product development with the intention to prolong mucosal drug residence time and to enhance absorption of drugs. The name thiomer was coined by Andreas Bernkop-Schnürch in 2000. Thiomers have thiol bearing side chains. Sulfhydryl ligands of low molecular mass are covalently bound to a polymeric backbone consisting of mainly biodegradable polymers, such as chitosan, hyaluronic acid, cellulose derivatives, pullulan, starch, gelatin, polyacrylates, cyclodextrins, or silicones.
Thiomers exhibit properties potentially useful for non-invasive drug delivery via oral, ocular, nasal, vesical, buccal and vaginal routes. Thiomers show also potential in the field of tissue engineering and regenerative medicine. Various thiomers such as thiolated chitosan and thiolated hyaluronic acid are commercialy available as scaffold materials. Thiomers can be directly compressed to tablets or given as solutions.  In 2012, a second generation of thiomers – called "preactivated" or "S-protected" thiomers – were introduced. 
In contrast to thiomers of the first generation, preactivated thiomers are stable towards oxidation and display comparatively higher mucoadhesive and permeation enhancing properties. Approved thiomer products for human use are for example eyedrops for treatment of dry eye syndrome or adhesive gels for treatment of nickel allergy.