Synthesis and Solution Processing of a Rigid Polymer Enabled by Active Manipulation of Intramolecular Hydrogen Bonds

Abstract

Global intramolecular hydrogen bonds were installed and manipulated in a rigid artificial synthetic polymer in order to actively control its conformation for synthesis and processing. The polymer solubility was switched on and off by chemically inhibiting and regenerating these preorganized intramolecular hydrogen bonds. Such active manipulation made it possible to synthesize this highly rigid polymer with elevated molecular weights. A well-solubilized, noncoplanar polymer precursor with thermally cleavable Boc groups was synthesized (M n = 32.4 kg/mol). After processing this precursor into thin films, in situ thermal treatment regenerated the latent intramolecular hydrogen bonds and led to a rigid ladder-type conformation. Such manipulation of the intramolecular hydrogen bonds allowed for multilayer deposition of this polymer, laying the foundation for potential additive manufacturing using this strategy.

Optimizing the self‐assembly of conjugated polymers and small molecules through structurally programmed non‐covalent control

“…21 This can be achieved by including substituents that can participate in hydrogen bonding, and can yield more complex secondary structures such as nanofibers. 22,23 Like conjugated polymers, conjugated oligomers can model hydrogen bonding self-assembly, as they can be rigorously purified, and their three-dimensional structure can be precisely elucidated through X-ray crystallography and other means. As with polymers, the intramolecular configuration, as well as the intermolecular assembly of oligomers can impact the semiconducting abilities of conjugated oligomers.…”

“…Selected chemical structures of some hydrogen bonding conjugated polymers and oligomers. 23,24,30,32,36 Hydrogen bond donor and acceptor groups (blue) form hydrogen bonding interactions (red dashes) and can be intramolecular (top) or intermolecular (bottom) in nature, depending on structure F I G U R E 2 Schematic representation of two-dimensional supramolecular material developed by Li et al Reproduced with permission. 41 Copyright 2017, Wiley-VCH as an effective cross-linking method, as demonstrated by Nyayachavadi et al, 42 in which isoindigo-based donoracceptor polymers were appended with reactive 1,3-butadiyne groups that self-assembled due to hydrogen bonding amides within the butadiyne chains.…”

“…A relatively common function of hydrogen bonding interactions within conjugated materials is to control both their intramolecular and intermolecular structural configurations in the solid state 21 . This can be achieved by including substituents that can participate in hydrogen bonding, and can yield more complex secondary structures such as nanofibers 22,23 . Like conjugated polymers, conjugated oligomers can model hydrogen bonding self‐assembly, as they can be rigorously purified, and their three‐dimensional structure can be precisely elucidated through X‐ray crystallography and other means.…”

“…Selected chemical structures of some hydrogen bonding conjugated polymers and oligomers 23,24,30,32,36 . Hydrogen bond donor and acceptor groups (blue) form hydrogen bonding interactions (red dashes) and can be intramolecular (top) or intermolecular (bottom) in nature, depending on structure…”

One‐Step Route to Ladder‐Type C–N Linked Conjugated Polymers

“…Ladder‐type conjugated polymers are a specific subtype of ladder polymers in which all the fused rings in the backbone are pi‐conjugated, which have raised considerable interest because of their unique structures and attractive properties . Many attempts have been made to explore novel approaches for synthesizing new class of ladder‐type conjugated polymers . Müllen's group developed the route to ladder‐type pentaphenylenes by syntheses via a pentaphenylene intermediate which was then treated with boron trifluoride to afford a blue‐emitting ladder‐type pentaphenylene .…”