Modulating the properties of azulene-containing polymers through controlled incorporation of regioisomers

Two libraries of random conjugated polymers are presented that incorporate varying ratios of regioisomeric azulene units connected via the 5-membered or 7-membered ring in combination with bithiophene or fluorene comonomers. It is demonstrated that the optoelectronic and stimuli-responsive properties of the materials can be systematically modulated by tuning the relative percentage of each azulene building block in the polymer backbone. Significantly, these materials exhibit stimuli-responsive behavior in the solid state with spin-coated thin fi lms undergoing rapid and reversible color switching. Ultimately, this work introduces a new design strategy in which the optoelectronic properties of conjugated polymers can be modulated by varying only the regiochemistry of the constituent building blocks along a polymer chain.