Syntheses, properties and applications of fully conjugated ladder polymers are reviewed, together with an outlook to future opportunities and challenges.

The synthesis of a carbazole-derived, well-defined ladder polymer was achieved under thermodynamic control by employing reversible ring-closing olefin metathesis.

Well-defined, fused-ring aromatic oligomers represent promising candidates for the fundamental understanding and application of advanced carbon-rich materials, though bottom-up synthesis and structure-property correlation of these compounds remain challenging. In this work, an efficient synthetic route was employed to construct extended benzo[k]tetraphene-derived oligomers with up to 13 fused rings. The molecular and electronic structures of these compounds were clearly elucidated. Precise correlation of molecular sizes and crystallization dynamics was established, thus demonstrating the pivotal balance between intermolecular interaction and molecular mobility for optimized processing of highly ordered solids of these extended conjugated molecules.

Organic solvent nanofiltration (OSN) membranes composed of aromatic porous polymer networks are fabricated by in situ cross-linking. They exhibit excellent chemical/structural stability, molecular-sieving selectivity, and high permeability for OSN.

Molybdenum disulfide (MoS2) is a promising earth-abundant and low-cost electrocatalyst for the hydrogen evolution reaction (HER). In this study, we describe a stepwise synthetic approach comprising vapor transport, reduction, and topochemical sulfidation for creating 3D arrays of MoS2 nanosheets directly integrated onto carbon fiber paper (CFP) substrates. The sulfidation process results in a high density of edge sites along both the edges and the basal planes of MoS2. The obtained materials characterized by a high density of exposed edge sites exhibit promising electrocatalytic performance, including an overpotential (η10) of 245 mV at 10 mA/cm2, a Tafel slope of 81 mV/dec, and a turnover frequency (TOF) of 1.28 H2/s per active site at −0.2 V vs RHE in a 0.5 M acidic solution. The electrocatalytic properties of the MoS2 nanosheets are observed to be substantially enhanced by interfacing with solution-deposited buckminsterfullerene nanoclusters (nC60). A coverage of ca. 2% of nC60 yields a hybrid electrocatalyst exhibiting an η10 value of 172 mV, a Tafel slope of 60 mV/dec, and a TOF value of 2.33 H2/s per active site at −0.2 V vs RHE. The enhancement of electrocatalytic activity is found to derive from interfacial charge transfer at nC60/MoS2 p–n heterojunctions. The high conductivity of the interfacial layer formed as a result of charge transfer from nC60 to MoS2 is thought to substantially mitigate the limitations imposed by the poor basal plane conductivity of undoped MoS2. The hybrid catalysts illustrate an important design principle involving the use of structured interfaces to enhance the catalytic activity of low-dimensional materials.

The construction of coplanar conjugated ladder polymers featuring alternating donor–acceptor units has been achieved in high efficiency using ring-closing olefin metathesis.

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To improve methane storage capacity of porous organic materials, this work demonstrates that a rigid ladder-type backbone is more entropically favorable for gas adsorption and leads to a high gas uptake per unit surface area. A porous ladder polymer network was designed and synthesized as the model material via cross-coupling polymerization and subsequent ring-closing olefin metathesis, followed by characterization by solid-state nuclear magnetic resonance (NMR) spectroscopy. This material exhibited a remarkable methane uptake per unit surface area, which outperformed those of most reported porous organic materials. Variable-temperature thermodynamic adsorption measurements corroborated the significantly less negative entropy penalty during high-pressure gas adsorption, compared to its non-ladder-type counterpart. This method provides an orthogonal strategy for multiplying volumetric methane uptake capacity of porous materials. The entropic approach also offers the opportunity to increase deliverable gas upon pressure change while mitigating the performance decline in high-temperature applications.