Polymers of intrinsic microporosity (PIMs) have shown promise in pushing the limits of gas separation membranes, recently redefining upper bounds for a variety of gas pair separations. However, many of these membranes still suffer from reductions in permeability over time, removing the primary advantage of this class of polymer. In this work, a series of pentiptycene-based PIMs incorporated into copolymers with PIM-1 are examined to identify fundamental structure–property relationships between the configuration of the pentiptycene backbone and its accompanying linear or branched substituent group. The incorporation of pentiptycene provides a route to instill a more permanent, configuration-based free volume, resistant to physical aging via traditional collapse of conformation-based free volume. PPIM-ip-C and PPIM-np-S, copolymers with C- and S-shape backbones and branched isopropoxy and linear n-propoxy substituent groups, respectively, each exhibited initial separation performance enhancements relative to PIM-1. Additionally, aging-enhanced gas permeabilities were observed, a stark departure from the typical permeability losses pure PIM-1 experiences with aging. Mixed-gas separation data showed enhanced CO₂/CH₄ selectivity relative to the pure-gas permeation results, with only ∼20% decreases in selectivity when moving from a CO₂ partial pressure of ∼2.4 to ∼7.1 atm (atmospheric pressure) when utilizing a mixed-gas CO₂/CH₄ feed stream. These results highlight the potential of pentiptycene’s intrinsic, configurational free volume for simultaneously delivering size-sieving above the 2008 upper bound, along with exceptional resistance to physical aging that often plagues high free volume PIMs. Significance Gas separation membranes are an emerging energy-efficient alternative toward conventional, energy-intensive separation technologies such as cryogenic distillation. Ladder polymers with intrinsic microporosity show exceptional promise toward redefining state-of-the-art gas separation membranes due to their high permeability (throughput) and selectivity (separation efficiency). However, they are typically inhibited by major reductions in permeability over time due to collapsing membrane free volume (open space between polymer chains), forfeiting their greatest asset. This work explores a route toward enhanced aging resistance and overall separation performance by incorporating pentiptycene (an H-shaped scaffold containing five fused arene rings) into ladder-like polymers to incorporate natural, more permanent “micropores” that aren’t susceptible to densification of polymer chains that occurs over time in traditional microporous polymers.

Directed high-speed motion of nanoscale objects in fluids can have a wide range of applications like molecular machinery, nano robotics, and material assembly. Here, we report ballistic plasmonic Au nanoparticle (NP) swimmers with unprecedented speeds (~336,000 μm s⁻¹) realized by not only optical pushing but also pulling forces from a single Gaussian laser beam. Both the optical pulling and high speeds are made possible by a unique NP-laser interaction. The Au NP excited by the laser at the surface plasmon resonance peak can generate a nanoscale bubble, which can encapsulate the NP (i.e., supercavitation) to create a virtually frictionless environment for it to move, like the Leidenfrost effect. Certain NP-in-bubble configurations can lead to the optical pulling of NP against the photon stream. The demonstrated ultra-fast, light-driven NP movement may benefit a wide range of nano- and bio-applications and provide new insights to the field of optical pulling force.