Formation and characterization of chitosan-based coatings on stainless steel

Chitosan, the second most abundant organic material on earth, is a bio-polymer found in crustaceans, fungi, insects, bacterial spore coats and other natural sources and has been successfully used in medical applications, such as wound dressings and delivery of pharmaceuticals, and in environmental treatment applications, such as sorption of heavy metals. Chitosan provides a low cost and safe base material for development of functionalized coatings. A strong scientific underpinning is needed if such 'green' biomaterials are to be developed and used effectively for engineering applications. In particular, it is important to understand mechanisms for creating composite chitosan-based materials with strong interfaces. In this paper, we demonstrate the formation of adherent, durable layers of chitosan on stainless steel substrates, through a recently developed electrochemical method. Spectroscopic (X-ray diffraction and FTIR and Raman spectroscopies) and mechanical testing (atomic force acoustic microscopy, microscratch tests and tribotesting) are used to characterize the structure and properties of the deposited materials. Chitosan-based layers are formed relatively quickly, and demonstrate a number of properties which suggest new engineering applications, including environmental, biomedical and mechanical uses.