Determination of the Orientation of Pendants on Rigid‐Rod Polymers.

Bis‐norbornene and bis‐cyclobutene with different kinds of linkers have been extensively used for the synthesis of double stranded ladderphanes under ruthenium‐ or molybdenum‐catalyzed ring opening metathesis polymerization (ROMP) conditions. The key to the success relies on the selective formation of comb‐like polynorbornenes or polycycloubtenes, where pendants are all aligned towards similar direction. This minireview summarizes various methods (chemical methods, spectroscopic means, and nonlinear optical measurements) for determining the comb‐like conformations of pendants on these rigid‐rod polymers. The approach is based on the proximal relationship between adjacent pendants. Interactions between these adjacent pendants would enable a change in chemical reactivity [ABSTRACT FROM AUTHOR]