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Abstract Helical poly(isocyanide)s are an important class of synthetic polymers possessing a static helical structure. Since their initial discovery, numerous examples of these helices have been fabricated. In this contribution, the synthesis of a chiral, azobenzene (azo)‐containing isocyanide monomer is reported. Upon polymerization with nickel(II) catalysts, a well‐defined circular dichroism (CD) trace is obtained, corresponding to the formation of a right‐handed polymeric helix. The helical polymer, dissolved in chloroform and irradiated with UV light (365 nm), undergoes acistotransisomerization of the azobenzene side‐chains. After the isomerization, a change in conformation of the helix occurs, as evidenced by CD spectroscopy. When the solution is irradiated with LED light, the polymer returns to a right‐handed helical conformation. To open up the possibility for chain‐end post‐polymerization modification of this light‐responsive system, an alkyne‐functionalized nickel(II) catalyst is also used in the polymerization of the azobenzene monomer, resulting in a stimuli‐responsive, terminal‐alkyne‐containing helical poly(isocyanide).
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Orthogonal Images Concealed Within a Responsive 6‐Dimensional Hypersurface
Abstract A photochemical printer, equipped with a digital micromirror device (DMD), leads to the rapid elucidation of the kinetics of the surface‐initiated atom‐transfer radical photopolymerization ofN,N‐dimethylacrylamide (DMA) andN‐isopropylacrylamide (NIPAM) monomers. This effort reveals conditions where polymer brushes of identical heights can be grown from each monomer. With these data, hidden images are created that appear upon heating the substrate above the lower critical solution temperature (LCST) of polyNIPAM. By introducing a third monomer, methacryloxyethyl thiocarbamoyl rhodamine B, a second, orthogonal image appears upon UV‐irradiation. With these studies, it is shown how a new photochemical printer accelerates discovery, creates arbitrary patterns, and addresses long‐standing problems in brush polymer and surface chemistry. With this technology in hand a new method is demonstrated to encrypt data within hypersurfaces.
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- Award ID(s):
- 2032176
- PAR ID:
- 10449332
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials
- Volume:
- 33
- Issue:
- 21
- ISSN:
- 0935-9648
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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