Permeability of block copolymers to vapors and liquids

Permeability of block copolymers is an important feature for a broad range of applications including packaging, bio-materials (e.g. for controlled release or encapsulating membranes), barrier materials, high performance impermeable breathable clothing and membrane separation processes. This paper reviews the literature on permeability of block copolymers to pure or mixed vapors and liquids for the past 40 years. Different types of block copolymers are considered, starting with the most investigated polyurethanes and polyurethaneureas followed by polyimides, polyamides and miscellaneous types of block copolymers (e.g. block copolymers containing siloxane segments, hydrocarbon block copolymers and related materials). Block copolymers offer a great structure versatility which is highly interesting for a fundamental analysis of permeation through polymeric materials. A special attention has been paid to the key permeability properties and their correlation to the chemical structure of block copolymers. Systematic structure/property relationships have been emphasized to promote the future design of block copolymers with improved permeability properties. Far from being limited to fundamental investigations, this literature review points out the originality of block copolymers, which combine a great structure versatility with several high potential industrial prospects. Many patents on block copolymers indeed reflect a strong industrial interest in applications based on their (selective) permeability. A sharp increase in the related patents for the past 10 years certainly shows the strong potential of block copolymers to take up several current challenges in the medical, chemical and petrochemical fields. (C) 2002 Elsevier Science Ltd. All rights reserved.