(4e) Surface and Interface of Soft Materials

Surface and interface properties of soft materials (e.g. polymers) are governed by the first few nanometers on their surfaces or interfaces. These very small fractions of a material not only affect the bulk properties, but also dominate the surface energy, wetting behavior, adhesion, biocompatibility, and so on. A modification or treatment of the surface and interface can lead to dramatic changes in these properties. In this paper, I will demonstrate the importance of the surface and interface to a material with several research projects I have been involved. My future research interests revolving around these surface and interface phenomena will also be discussed. The examples will be presented in this paper are as follows: 1. Very strong dependence of the magnetic fluids and magnetic polymer particles containing magnetic particles on the dispersion, surfactant and the surface morphology of the particles was discovered. 2. Polymer blend or composite requires a compatiblizer or a surfactant to achieve the desired miscibility or dispersion for the target application. Block copolymers were designed to maintain a certain degree of immiscibility for control of morphology. 3. Particle formation using supercritical fluids utilizes the super low surface tension of supercritical fluids to prevent the aggregation of free particle products with very high surface area. 4. Other examples of the surface and interface phenomena will be discussed together with applications in polymer welding, adhesion, autohesion, lamination, and polymer coatings. 5. My current research involves polymer surface modification using a semi-fluorinated polymer or copolymer, which renders the surface a low surface free energy and tunable morphologies and topologies. Applications of such surfaces can be found in antimicrobial, antifouling, control of hydrophobicity and oleophobicity, biocompatible and biostable biomedical devices, etc.