ABSTRACT
In the pharmaceutical and packaging industries, lms are dened as a ne layer to protect drugs or food materials. Films can be formed into pouches, capsules, bags, or casings through further fabrication processes. However, coatings are a particular form of lms directly applied to the surface of materials. They usually consist of biopolymers and food-grade additives able to provide mechanical strength and other important functions [1]. Films mainly limit diffusion of water vapor, oxygen, carbon dioxide, and so on, and enhance the quality of drugs and food products, protecting them from physical, chemical, and biological deterioration. Film-forming biopolymers can be proteins (gelatin, gluten, etc.), polysaccharides (starch, cellulose, chitosan, etc.), or lipids (waxes, fatty acids, etc.). They can also be hydrophilic or hydrophobic and the solvents used are restricted to water and ethanol. Surfactants, plasticizers, and other additives are combined with the lm-forming biopolymers to modify the physical properties or functionality of lms [2-5]. In the last few years, research has focused on the development of lms and coating from environmentally friendly materials. Among these, polysaccharide polymers such as cellulose ethers (carboxymethyl cellulose (CMC), methylcellulose (MC), hydroxypropyl methylcellulose (HPMC)), and chitosan have been particularly studied [6-9]. The use of these materials presents many advantages including widespread availability, low cost, and biodegradability.
