Surface Modification of PolymersThe nature of the surface of the materials used in a product increasingly determines its success in almost every industry. This is true whether one is dealing with surface cleanliness, bonding of different components, biocompatibility, or mechanical performance of the part under conditions of use.
However, in most cases, an engineering polymer for instance is selected for a given application primarily because of its favorable bulk properties, such as thermal stability, mechanical strength, solvent resistance, cost, etc. The selected polymer has often surface characteristics that are less than optimum for the intended application. To correct this, the strategy of surface modification has been implemented.
Polymer surfaces can thereby be changed to achieve a variety of goals, including increasing adhesion, improving wettability, reducing friction, reducing susceptibility to harsh chemicals or environmental agents, and increasing dye absorption.
The inherent solvent resistance and lack of reactivity of engineering polymers imply that fairly aggressive and/or specialized procedures are required to achieve surface modification. The most commonly used procedures can be conveniently divided into two major categories: Conventional (wet) methods and energetic (dry) methods. The former group includes e.g. wet chemical oxidation, well-defined functionalization by classical organic chemistry and covalent attachment of polymer chains (e.g. graft polymerisation or polymer grafting). The latter group comprises e.g. plasma surface modifications, flame, ultraviolet, laser and corona surface treatments.