Spontaneous Transport across Locally Nonchaotic Molecular-Sized Outward-Swinging Gates

In this research, we investigate an interesting concept: molecular-sized outward-swinging gates, which may be viewed as a locally nonchaotic entropy barrier. Our theoretical analysis, Monte Carlo simulation, and brutal-force solution of governing equations all indicate that across such gates, under the condition of local nonchaoticity, the probability of particle crossing is effectively asymmetric. It was confirmed experimentally by using a nanoporous membrane one-sidedly surface-grafted with bendable organic chains. Remarkably, across the membrane, gas could flow form the low-pressure side to the high-pressure side. The transport process was spontaneous and repeatable.



We show that although the phenomenon seems counterintuitive, it strictly follows the basic principle of maximum entropy. What makes the system unique is that the gates interrupt the probability distribution of local microstates, and impose additional constraints on the global microstates, so that entropy is maximized to a nonequilibrium maximum.



This finding will have profound impacts on many aspects of statistical mechanics. It may enable high-efficiency heat and mass transfer, novel metamaterials, high-efficiency energy harvesting, etc.