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Abstract The fabrication of truly hierarchically folded single‐chain polymeric nanoparticles with primary, secondary, and defined 3D architecture is still an unfulfilled goal. In this contribution, a polymer is reported that folds into a well‐defined 3D structure from a synthetic sheet‐helix block copolymer. The sheet‐like poly(p‐phenylene vinylene) (PPV) block is synthesized via the ring‐opening metathesis polymerization of a thymine‐bearing dialkoxy‐substituted [2.2]paracyclophane‐1,9‐diene. The PPV block is terminated with a Pd complex using a Pd‐containing chain‐terminating agent. The terminal Pd complex catalyzes the polymerization of isocyanide monomers with side‐chains containing either a chiral menthol or an achiral diaminopyridine resulting in the formation of a helical poly(isocyanide) (PIC) random copolymer. The PIC side‐chains are capable of engaging in complementary hydrogen‐bonding with thymine units along the PPV block resulting in the folding of the two secondary structural domains into a well‐defined 3D structure. The folding and unfolding of the polymer in both chloroform and THF are monitored using dynamic light scattering and NMR spectroscopy. This work is the first example of a hierarchically folded synthetic polymer featuring a defined 3D structure achieved by using two different polymer backbones with two distinct secondary structures.
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Functionalized [2.2]Paracyclophanedienes as Monomers for Poly( p -phenylenevinylene)s
Poly(p-phenylenevinylene)s (PPVs) featuring complex side-chains, to date, have only been synthesized by non-living polymerization methods which have no control over PPVs molecular weights, dispersities, or end groups. [2.2]Paracyclophane-1,9-diene (pCpd) have gained attention as a monomer for its ability to be ring-opened to PPV in a living fashion. pCpd, an organic cyclic scaffold with planar chirality, has seen minimal structural diversity due to the harsh reaction conditions required to afford the highly strained compound. Herein, we introduce a general method to overcome this by targeting the synthesis of a monohydroxy-pCpd via mono-demethylation of a dialkoxy-pCpd. The monohydroxy-pCpd can then be functionalized easily which we demonstrate using three distinct side-chains with four moieties commonly incorporated in conjugated polymers: an alkyl bromide, an oligo(ethylene glycol) chain, an enantiomerically pure side-chain, and a Boc-protected amine. These monofunctionalized-pCpds were investigated as monomers in the ring-opening me-tathesis polymerizations (ROMP) to afford functionalized PPVs in a living manner. The functional group-containing PPVs are synthe-sized with full control over their end groups, repeat units, and dispersities. The feasibility of post-polymerization modifications to incor-porate any desired moiety to PPV fabricated by this method was demonstrated using an azide-alkyne click reaction. All PPVs synthesized were soluble in organic solvents and display the same fluorescent emission indicating their conjugated backbones are unaltered.
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- Award ID(s):
- 2203929
- PAR ID:
- 10494056
- Publisher / Repository:
- American Chemical Society
- Date Published:
- Journal Name:
- ACS Macro Letters
- ISSN:
- 2161-1653
- Page Range / eLocation ID:
- 112 to 117
- Subject(s) / Keyword(s):
- Chemistry, Polymers, self-assembly
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1021/acsmacrolett.3c00714
