Polymer coatings for membrane applications

 
Separation of different gases or liquids is an often encountered task in our everyday life. Separation of CO2 from natural gas or separation of nitrogen from oxygen are typical examples for gas separation, while the purification of water from bacteria or viruses is a typical example for a liquid system. Polymer membranes are powerful tools for these and similar separation tasks, as both the chemical composition of a polymer and the way it is processed to become a membrane are most influential on its final properties. In comparison to inorganic membranes, polymer-based membranes are much cheaper and also easier in handling. To achieve a good performance, membranes should have a thin separating layer, which is mechanically supported by a suitable substructure. The substructure should ne contribute resistivity against the flux. Then the membrane can achieve a good selectivity and a good permeability at the same time, which is the goal in membrane development. In this contribution different examples of thin film polymer membranes and their preparation will be presented and discussed. These include block copolymer membranes for gas and liquid separations. as well as thermally rearranged polymers, which represent a novel class of polymer materials for membrane production.