poly[N-(1-naphthyl)-N’-(n-octadecyl)carbodiimide (PNOC) displays distinct, reversible chiroptical switching, exhibiting varying ranges of specific optical rotation (SOR) values dependent upon temperature and solvent. PNOC’s chiroptical switching behavior have been detailed using variable temperature/solvent 15N NMR, calculated and theoretical models of VCD, and React-IR studies, with SOR’s ranging from +1050 for DCM and -790 for benzene. The identical, theoretical, and calculated models of VCD spectra for PNOC confirms that the polycarbodiimide backbone does not undergo helical inversion, but the chiroptical switching were due to the uniform flip of the pendant naphthyl rings.<br/>With PNOC’s heightened sensitivity to various solvents, state A v. state B population can be quantified depending on the solvent’s effect on PNOC, with benzene occupying the state A conformation, while DCM occupies the state B conformation. The chiroptical switching behavior was then subjected to RT-FTIR studies to quantitatively and qualitatively observe PNOC’s sensitivity to volatile organic compounds and their occupation in the polymer’s two conformations, with precise distinctions between solvents such as DCM and chloroform, and various alkanes. Unique surface reorganization behavior was also exhibited by the interaction of the highly regioregular, helical polymer to various solvents evidenced by the dynamic contact angle over time. Characteristic liquid crystal phases were also observed with the polymers reorganization in solvents such as benzene, chloroform, THF and Toluene.

Solid state sensing of non-polar VOCs using the bistable expansion and contraction of helical polycarbodiimides

255th National Meeting (2018)

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