Orthogonal self-assembly of stimuli-responsive supramolecular polymers using one-step prepared heterotelechelic building blocks

The one-step preparation of heterodifunctional telechelic polymers containing 2,2':6',2 ''-terpyridine (tpy) and 2-ureido-4[1H]-pyrimidinone (UPy) end-groups, as orthogonal supramolecular moieties, is reported. The utilization of an appropriately functionalized alkoxyamine, as an initiator for the nitroxide-mediated radical polymerization (NMP), directly constitutes the end-groups of the resultant polymers. The targeted alkoxyamines are based on the nitroxide structure of 2,2,5-trimethyl-3-(1-phenylethoxy)-4-phenyl-3-azahexane (TIPNO) and were obtained via stepwise functionalization of a heterodifunctional alkoxyamine skeleton. Controlled radical polymerization of styrenics using the alkoxyamine tpy-TIPNO-UPy, as an initiator, is demonstrated to generate well-defined telechelic polymers in one step. These telechelics represent promising building blocks for supramolecular architectures via self-assembly processes, yielding linear chain-extended polymers of high molar masses. Due to the orthogonality of the metal ion complexation and hydrogen bonding, the system can be addressed selectively by external stimuli. Besides for various applications, e.g. as self-healing materials, the strategy is highly attractive for tailoring the material's properties of supramolecular polymers, since the nature and the length of the polymer chain between the terminal supramolecular motifs can be controlled in a facile way.