Assessment of nanoadhesion and nanofriction properties of formulated cellulose-based biopolymers by AFM

Abstract

Hydroxypropyl methylcellulose (HPMC) constitutes one of the most dedicated polymers used in the production of film coatings for pharmaceutical applications (capsules, tablets, etc.). 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, nanoadhesion, and nanofriction properties of HPMC-formulated films. At nanoscale, atomic force microscopy in contact mode and in friction mode is a powerful tool for studying nanoadhesion and nanofriction. The presented chapter 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.