Physical Mechanism Behind Non‐Monotonic Distribution of Gel Properties Induced by Centrifugal Polymerization

ABSTRACT Technologies for formation of polymer materials with a given spatial distribution of properties are widely in demand in both scientific and industry applications. Various chemical or physical effects are used to control the formation of polymers and influence their properties, enabling the creation of materials with controlled property gradients. Among the physical effects the use of centrifugal field is one of the most effective ways. Usually it is believed that this mechanism is able to form only a monotonous distribution of properties in the radial direction. In our work, the possibility of obtaining a non‐monotonic distribution of optical and mechanical polymer properties during polymerization in centrifuge is demonstrated by the example of acrylamide polymer. The use of interferometry in real‐time visualization of the polymerization process allowed us to demonstrate a key role of convective motion in the final distribution of polymer properties. The magnitude of the refractive index inhomogeneity turned out to be on the order of 10 −3 . We propose a physical mechanism responsible for the formation of a non‐monotonic distribution of polymer properties based on the competition of several effects at once: free convection, convection in a porous medium, and edge effects.