Polycarbodiimides are a relatively new class of helical, rigid macromolecules that possess a variety of interesting properties such as chiroptical switching and liquid crystalinity. By incorporating specific and modifiable functional groups at the end terminus of the polycarbodiimide chain, an interesting class of block copolymers can be synthesized containing both a chiral, helical block and a random coil block. Herein, we report the precise synthesis of alkyne end functionalized polycarbodiimides using functional Ni(II) initiators. Azide end capped polystyrene and poly(methyl methacrylate) were synthesized using atom transfer radical polymerization (ATRP) followed by post polymerization functionalization of the bromide end group with azidotrimethylsilane. These two specifically functionalized polymers undergo copper mediated alkyne-azide [3+2] cycloaddition (CuAAC) to yield rod-coil diblock copolymers. The thin film morphologies of these polymers are examined with tapping-mode atomic force microscopy (TM-AFM) and powder X-ray diffraction (XRD). Additionally, the chiroptical and thermal characterization of these polymers are reported using electronic circular dichoroism (ECD), vibrational circular dichroism (VCD), and differential scanning calorimetry (DSC).

Precise synthesis and characterization of novel rod coil diblock copolymers with helical, chiral polycarbodiimides segments

247th National Meeting (2014)

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