Chemistry Reference
In-Depth Information
Figure 5.15 Examples of linker cross-linked polymer networks exhibiting liquid crystalline
polymer characteristics.
They demonstrated that the linker length influenced the median diameter of the
spherical aggregate that was formed, resulting in good control over the aggregate
dimension.
Nair and Weck (2007) extended this approach by using a recognition motif
attached to the polymer that is able to form two different and potentially competing
hydrogen bonding motifs. This strategy has the potential to tailor material properties
as well as the degree and strength of the cross-linking in a highly controllable fashion.
The Weck system is based on a polynorbornene backbone that was functionalized
with cyanuric acid groups (poly-CA) along the side chains. The cyanuric acid
side chains then could be noncovalently cross-linked with linker molecules by
hydrogen bonding interactions in two distinct ways: with three-point cyanuric
acid-diaminotriazine or six-point cyanuric acid-Hamilton wedge interactions as
shown in Figure 5.17.
Figure 5.16 2,6-Diaminopyridine side chain functionalized polystyrene cross-linked via
bis-thymine cross-linking agents.
