Authors: M. Brogly, A. Fahs, S. Bistac
Hydroxypropyl methylcellulose (HPMC) constitutes one of the most dedicated polymers used in the production of film coatings for pharmaceutical applications (capsules, tablets …). In order to control the surface properties of HPMC films, additives are frequently incorporated during film formulation: these are in most cases hydrophobic lubricant (like fatty acids) or hydrophilic plasticizer (like polyethylene glycol). The main objective is to present the surface characteristics in terms of structuration, surface morphologies, surface phase separation, surface energy, nano-adhesion and nano-friction properties of HPMC formulated films. At nanoscale, Atomic Force Microscopy (AFM) in contact mode and in friction mode (FFM) is a powerful tool for studying nano-adhesion and nano-friction. The presented paper underlines the strong dependence of film surface properties on additive nature, concentration and/or water sensitivity. It also shows that first the HPMC-additive compatibility seems to be an interesting factor behind the variation of surface properties of HPMC formulated films, and second that formulation is an effective way to tune surface properties of HPMC biopolymer films.
Keywords: HPMC biopolymer, Cellulose-based films, Nano-adhesion, Nano-friction, Atomic Force Microscopy