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stract This article reviews polymer behavior at the air-water interface with a focus on the Langmuir technique and spreading processes to gain insight into this interface. The influence of the solvent and the water subphase on some polymer monolayers is discussed. The surface pressure–area isotherms (π–A) are described in terms of the chemical structure and the hydrophilic-hydrophobic balance of selected polymeric systems, with an emphasis on the behavior of the specific diblock copolymer films at the air-water interface. In some cases, molecular dynamic simulation studies can be used to visualize the organization and orientation of polymers at the air-water interface and to identify the main molecular interactions involved in such processes.

a variety of organizational and dynamic interfacial behaviors dependent on the chemical structure of the molecule and its affinity with the phases. These phases can be two non-miscible solvents or one solvent and air (air-water interface). When the molecule is a macromolecule or a polymer, the interactions between polymers adsorbed onto the surface lead to important properties. For example, it is believed that polysaccharides incorporated into the membrane of a cell are responsible for the cell adhering onto a surface, and polymers adsorbed onto surfaces also play an important role in stabilizing industrial colloidal dispersions such as paints and inks.16 A number of techniques have been used to study the structure of polymers at interfaces, such as nuclear magnetic resonance,17–19 electron spin resonance,20 surface quasi-elastic light scattering,21 ellipsometry,22 and Brewster angle microscopy.22

Langmuir Technique. Air-Water Interface The air-water interface is one of the most studied interfaces because it occurs in many materials systems. Langmuir films reside at the air-water interface. The films can be formed using a Langmuir trough-Wilhelmy plate method (Figure 1). Polymer monolayers are spread onto the aqueous subphase (air-water interface) using organic solvent solutions. After spreading, the monolayer is allowed to equilibrate (about 20 minutes),

Introduction Most of the polymeric materials used in our daily lives are composed of several phases, so it is of interest to know the properties of these phases, particularly of their interfacial regions.1 The boundary between a liquid and a gas or a liquid and another liquid marks a transition between the composition and properties of two bulk phases. A surface layer exists with different properties from those of either bulk phase. This is an interface region. Certain molecules will orient themselves at the interface between a gaseous and a liquid phase (air-water interface) to minimize their free energy. The resulting surface film is one molecule thick, commonly called a monolayer. A Langmuir monolayer is a film of amphiphilic molecules on a water surface. Over the last three decades, data have been accumulated on the Langmuir monolayer formation of preformed polymers on water and their spreading behavior.2–4 This article