Yan Xia

Our interest in unique ladder-shaped (macro)molecules led to the development of unusual materials. We developed Catalytic Arene-Norbornene AnnuLation (CANAL) to synthesize ladder polymers consisting of fused conformationally rigid rings from norbornadiene and aryl bromides. The produced hydrocarbon ladder polymers show high thermal and chemical stability and high microporosity. Mechanically robust membranes from these polymers exhibit a strong size-sieving effect, leading to excellent performance in energy-efficient chemical separations, which account for half of total industrial energy consumption in the US. We also developed several families of polymers with ladder-type repeat units that readily rearrange their backbone structures under various mechanical stimuli. The mechanochemical backbone rearrangement dramatically changes all the intrinsic properties of polymers at once. Mechanistic study revealed intriguing non-equilibrium dynamic effects and cascade reactivities as well as features that significantly lower the threshold force for response. Understanding of mechanically triggered molecular reactivities guides the design of materials with multifaceted mechanical response and robust mechanical performance.

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