What Happens When Threading is Suppressed in Blends of Ring and Linear Polymers?

• Main Authors: Benjamin Crysup, Sachin Shanbhag
• Format: Article
• Language: English
• Published: MDPI AG 2016-11-01
• Series: Polymers
• Subjects: ring polymer; cyclic polymer; diffusion; probe diffusion; polymer blend; Monte Carlo simulation
• Online Access: http://www.mdpi.com/2073-4360/8/12/409

Self-diffusivity of a large tracer ring polymer, D r , immersed in a matrix of linear polymers with N l monomers each shows unusual length dependence. D r initially increases, and then decreases with increasing N l . To understand the relationship between the nonmonotonic variation in D r and threading by matrix chains, we perform equilibrium Monte Carlo simulations of ring-linear blends in which the uncrossability of ring and linear polymer contours is switched on (non-crossing), or artificially turned off (crossing). The D r ≈ 6 . 2 × 10 − 7 N l 2 / 3 obtained from the crossing simulations, provides an upper bound for the D r obtained for the regular, non-crossing simulations. The center-of-mass mean-squared displacement ( g 3 ( t ) ) curves for the crossing simulations are consistent with the Rouse model; we find g 3 ( t ) = 6 D r t . Analysis of the polymer structure indicates that the smaller matrix chains are able to infiltrate the space occupied by the ring probe more effectively, which is dynamically manifested as a larger frictional drag per ring monomer.