Topochemical photo-reversible polymerization of a bioinspired monomer and its recovery and repolymerization after photo-depolymerization

Abstract

Solid-state topochemical polymerization is one way to synthesize novel macromolecular architectures with stereoregular chain structures. Topochemical reactions are attractive, ''green'' synthetic pathways in material design, since they occur in solvent-free conditions and in response to external stimuli, such as heat and light. For the first time, we have used the reversible [2p + 2p]-cycloaddition of a bioinspired bis-thymine monomer to topochemically synthesize a polymer. The polymer can be fully photodepolymerized to the monomer and then reversibly and repeatedly photo-polymerized and photodepolymerized. This is the first demonstration of complete photo-depolymerization and subsequent monomer recycling using this mechanism.

Unraveling two-dimensional polymerization in the single crystal

“…Structure investigations of partially polymerized structures are rare and often restricted to a single intermediate state (Grimm et al, 1982;Albouy et al, 1983). Even rarer is work regarding depolymerization (Johnston et al, 2012). To the best of our knowledge, there has been no extensive structural and kinetic study of 2DPs with similar detail to the studies on 1DPs.…”

Wavelength-gated photoreversible polymerization and topology control

“…[50][51][52] As a consequence, previously reported polymerization reactions induced by photocycloadditions only occurred efficiently in the crystalline state upon precise alignment via crystal engineering. 53,54 We propose that the polymerization reaction described here proceeds efficiently for two reasons: (i) the combination of large aromatic systems with a polar PEG linker lead to a prearrangement of the styrylpyrene units in THF, favored by dispersion interactions between the large aromatic systems. (ii) The relatively low photon energies of the applied wavelengths (>430 nm) prevent non-specic photodamage of the reactive groups and polymeric backbone.…”

Light‐Responsive Polymer Membranes

“…Photodimerization is an interesting photoreversible reaction for its applications as photoresists, self‐healing materials, nanocarriers, and responsive polymers . In addition, dimerizations can be considered green chemistry reactions because photons do not leave residues and reactions can take place at room temperature and even in the solid state …”