Dynamics of Charged Ring Polymers under Gel Confinement

Abstract

Ring polymers are ubiquitous in various fields including biomaterials, drug release and gene therapy. All of these applications involve the dynamics and diffusion process of ring polymers in a confined environment. By using dynamic light scattering (DLS), we discovered a dynamical transition for charged ring polymers with increasing ring concentration in the gel matrix from a diffusive state to a non-diffusive topological frustrated state with a more compact conformation. When the ring polymer size is smaller than the mesh size of the gel matrix, the rings are diffusive at low concentration of 5 g/L. The ring diffusion coefficient in the gel matrix is an order of magnitude smaller than that of rings in solution, obeying the Ogston’s model. At high ring concentration of 40 g/L, the collective dynamical behavior of the charged rings exhibits a topologically frustrated non-diffusive state, which may originate from the inter-ring threading with the external confinement from the gel matrix. Based on our previous theoretical work, we also conjectured that in such a non-diffusive state, the ring polymers might adopt a more compact conformation with the overall size exponent v=1/3.