Conformationally asymmetric block copolymers

✍ Scribed by M. W. Matsen; F. S. Bates

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 228 KB
• Volume: 35
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/(sici)1099-0488(19970430)35:6<945::aid-polb9>3.0.co;2-g

✦ Synopsis

The standard parameters controlling AB diblock copolymer phase behavior are xN and f A , where x is an A-B segment interaction parameter, N is the overall degree of polymerization, and f A is the volume fraction of the A block. Recently, it has been recognized that the ratio of the A and B statistical segment lengths a A /a B also represents another important parameter. Here, we theoretically examine the effects of this latter parameter on the phase behavior using the standard Gaussian chain model. Calculations are performed using both self-consistent field theory (SCFT) and strong segregation theory (SST). The ratio a A /a B is shown to have strong effects on orderorder phase boundaries. Furthermore, it significantly affects the relative stability of the complex phases. In particular, it enhances the metastability of the perforated lamellar phase and may actually cause it to become an equilibrium structure. We also illustrate that varying a A /a B produces large changes in the relative domain spacings at order-order phase boundaries, which could strongly affect the kinetics of these transitions.