Valentina Gomez, Susan E. Walley, Ajeet Kumar, Will R. Henderson, James B. Young, Brent S. Sumerlin, and Ronald K. Castellano

Department of Chemistry, University of Florida, Gainesville, FL

Paracyclophanes (pCps) have drawn significant attention due to their unusual structures and ability to be selectively functionalized to bear a variety of functional groups that can greatly modify their properties. Previously reported in our group, pCp units were tetra-functionalized with amide groups that established transannular hydrogen bonds allowing a preorganization of the molecules to allow intermolecular hydrogen bonds to occur (K_e= 2175 ± 90). The result upon self-assembly is a helical π-stacked supramolecular polymer and based on enantiomer selection of the pCp, we can control the helicity of the assembly. Current literature involving pCp derivatives in materials applications focuses mainly on the substitution of the pCp core for enhanced optoelectronic properties. In our current work, we envision using the directional hydrogen-bonding abilities of these pCp derivatives to achieve higher order reversible morphologies. Through their supramolecular nature they will be a perfect scaffold for a polymeric supramolecular bottle-brush. The purpose of this work is to use [2.2]paracyclophane cores as a template to synthesize four arm star polymers via grafting-from polymerization techniques. The objective of synthesizing these novel pCp-polymer conjugates is to deduce their structure-property relationships and the effect of polymers on our previously reported pCp self-assembly behavior. The incorporation of polymeric arms to this supramolecular moiety would yield higher order morphologies with potential application as self-healable materials. To access grafting-from methodologies, the synthesis of macro ATRP initiators was achieved using pCp molecules with various substitution patterns to use as comparator molecules. Preliminary studies conducted via variable concentration ¹H-NMR and IR show the addition of the initiator moieties interfere with the self-assembly of the pCp units. Concurrently, optimization of photocatalyzed MMA polymerizations successfully yielded controlled radical polymerizations for all the targeted pCp-polymer conjugates. The use of a different initiating moiety and monomer was successfully explored, yielding encouraging results regarding the self-assembly behavior of the resulting initiator and pCp-polymer conjugates.