Strain-engineered particle diffusion in uniaxially deformed polymer networks

Precise control of particle diffusion is highly valuable in diverse modern technologies. Traditional methods for regulating particle diffusion are often limited by inherent properties of liquid medium. This study explores mechanical deformation as a new design space to engineer particle diffusion in stretchable soft materials. Combining experimental and theoretical analyses, we discover that particle diffusivity in a uniaxially deformed polymer network is governed by two dimensionless parameters: the ratio of particle size to the polymer network's mesh size and the stretch ratio applied to the polymer network. We further demonstrate a transition in the relationship between particle diffusivity and stretch ratio, characterized by a monotonic decrease for small particles and a non-monotonic trend for large particles. This transition is attributed to the synergistic effects involving geometric transformation of the deformed polymer network and energy modulation of the stretched polymer chains. This work introduces a new mechanism for controlling particle diffusivity in polymeric materials and establishes a theoretical foundation for developing previously inaccessible transport-based technologies.