Simulation study of the conformation and dynamics of substrate-supported ring and linear polymer films

The effects of chain topology on the conformational and dynamic properties of substrate-supported ring and linear polymer films were investigated by molecular dynamics simulations. The study reveals that the adsorbed ring polymer chains exhibit stronger adsorbability but less deformation than the linear ones. This results in a slower desorption of ring chains in a short time. However, over a long time, the desorption rate of the ring chain is larger because of the faster diffusion of the ring chain in bulk. In addition, the non-adsorbed chains in the interface region also exhibit obvious deformation and suppressed diffusivity due to the interchain interaction between non-adsorbed chains and adsorbed ones. The suppression degree of diffusivity is approximately the same for both films. The possible underlying physics is that the interchain interaction between non-adsorbed chains and adsorbed ones in the linear polymer films is overall stronger, but each non-adsorbed ring chain experiences stronger interchain interactions with the adsorbed chains. The results show that tails in the linear polymer film and loops in the ring polymer film play an important role in the interchain interaction.