Damage and Repair in Informational Poly(N‐substituted urethane)s

Abstract

The degradation and repair of uniform sequence‐defined poly(N‐substituted urethane)s was studied. Polymers containing an ω‐OH end‐group and only ethyl carbamate main‐chain repeat units rapidly degrade in NaOH solution through an ω→α depolymerization mechanism with no apparent sign of random chain cleavage. The degradation mechanism is not notably affected by the nature of the side‐chain N‐substituents and took place for all studied sequences. On the other hand, depolymerization is significantly influenced by the molecular structure of the main‐chain repeat units. For instance, hexyl carbamate main‐chain motifs block unzipping and can therefore be used to control the degradation of specific sequence sections. Interestingly, the partially degraded polymers can also be repaired; for example by using a combination of N,N′‐disuccinimidyl carbonate with a secondary amine building‐block. Overall, these findings open up interesting new avenues for chain‐healing and sequence editing.

Efficient molecular encoding in multifunctional self-immolative urethanes

“…These particular oligourethanes can be sequenced chemically, sans purification, via the self-immolation LC-MS protocol, providing a robust and highly accurate readout. 37 , 38 Further, parallel synthesis and sequencing methodologies were developed to afford rapid writing and reading. To demonstrate this paradigm, a passage from Jane Austen’s Mansfield Park was converted to a hexadecimal using our Mol.E-coder software and encoded in 18 oligourethanes.…”

Sequencing of Uniform Multifunctional Oligoesters via Random Chain Cleavages

“…Interestingly, a single LC–MS analysis was sufficient for a successful determination of the monomer order since every crucial fragment was present at a specific point in time. Using a similar approach, Lutz and co‐workers reported the self‐immolation of N‐substituted oligourethanes, whereby the depolymerization could be inhibited by increasing the spacer length between different carbamate moieties [26] . Whilst both examples provide interesting insights—sequencing by means of conventional MS 1 techniques remains a highly desirable feature for industrial applications—the majority of synthetic macromolecules is not able to spontaneously depolymerize upon the application of a certain stimulus.…”

Discrete, self-immolativeN-substituted oligourethanes and their use as molecular tags

“…[17][18][19][20][21][22][23][24][25][26] Using an analogous self-immolation process, Lutz and coworkers demonstrated that increasing the spacer length between the carbamate and the terminal alcohol of N-substituted oligourethanes resulted in decreased depolymerization kinetics. 27 In addition, the depolymerization could be completely stalled by making use of a longer hexyl spacer, which was utilized by the authors as a method to selectively erase specific parts of an informational sequence. However, no attempts were made to use this process for the molecular sequencing of the macromolecules, and the parameters that influence the rate of depolymerization were not further investigated.…”

“…Initially, a series of model studies were carried out to investigate which parameters influence the rate of the intramolecular cyclization event and, hence, impact the efficiency of the depolymerization process. While N-substituted oligourethanes are generally obtained via a solid-phase approach, [27][28][29] we herein describe a simple, robust and support-free strategy for their multigram scale synthesis. Finally, the oligomers were physically incorporated in a crosslinked polyurethane network in order to demonstrate their use as macromolecular anti-counterfeit tags that can be sequenced by means of ESI-or LC-MS.…”