Within the context of precision polymer synthesis, stereochemical control is highly desirable, as it affects many properties, such as crystallinity, solubility, thermal transitions and mechanical strength. In combination with controlled radical polymerization (CRP), stereoregular (helical) polymers also have well-defined molecular weight and dispersity, which provide a number of potential applications in materials science, including asymmetric catalysis, enantioselective separations and nonlinear optics. Moreover, chiral amplification is believed to be the second step in the evolution of homochirality, a fundamental property of life. The fact that a small number of chiral molecules (“sergeants”) can induce a preferred handedness in macromolecules consisting of achiral units (“soldiers”) raises the question as to whether or not solid chiral interfaces can induce a preferred handedness in surface-grown polymer chains. Individual cellulose nanocrystals (CNCs) and nanofibrils (CNFs) exhibit consistent right-handedness and thus offer a unique interface for macromolecular chirality induction. Here we present the results of recent experiments involving surface-initiated atom transfer radical polymerization (SI-ATRP) of achiral monomers from CNCs in aqueous media. ATRP initiators were either unselectively attached to CNC hydroxyl groups via esterification or selectively attached to the reducing end groups via <i>N</i>-hydroxysuccinimide/carbodiimide-mediated chemistry. Following SI-ATRP, surface-tethered polymers were cleaved from CNC interfaces and analyzed by <sup>1</sup>H NMR spectroscopy, gel permeation chromatography (GPC) and circular dichroism (CD). CNC reducing end-initiated CRP may not only provide a new route to chiral amplification, but also novel anisotropic patchy colloids for complex self-assembling systems.

Effect of cellulose nanocrystal chirality on the stereochemistry of surface-tethered polymers

253rd National Meeting (2017)

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