Polymer Surface Diffusion in the Dilute Limit

Abstract

The molecular weight (M) dependence of the surface diffusion coefficient (D) is measured for polystyrene adsorbed from chloroform, a good solvent, in the dilute limit of surface coverage. On as-received smooth quartz surfaces, we reproduce D ~ M -3/2 , the same power law observed earlier in aqueous systems for a much smaller range of M. This is consistent with computer simulations in the literature regarding 2D diffusion between obstacles. But on smoother surfaces, mica and thermally annealed quartz, we observe Rouse scaling, D ~ M -1 , to our knowledge the first time this theoretically-expected scaling has been observed for polymer diffusion at the solid-liquid interface. For polystyrene of the highest molecular weight diffusing on the rougher surfaces, in the range 1 to 6.7 x 10 5 g-mol -1 , the dependence on M softens to weaker than a power law of -3/2, suggesting reversion to Rouse behavior.

Computer simulation of soft matter at the growth front of a hard-matter phase: incorporation of polymers, formation of transient pits and growth arrest

“…These slow dynamics of the polymer at the interface then mean that growth occurs around it and the polymer is incorporated into the phase, in a process that is intrinsically very far from equilibrium. This prediction looks rather generic as it just relies on slow dynamics, and real three-dimensional polymers on surfaces have such slow dynamics 23,[25][26][27][28][29][30][31] . So although there are many differences between our model and experiments, because the effect is so generic, we expect that in both cases incorporation can be driven by the slow dynamics of the soft matter at the growth front failing to keep up with the advance of this front.…”

“…Diffusion of adsorbed single polymers at a surface can be studied in experiment, and the diffusion constant, D S , measured [29][30][31] . If this could be done on a growing crystal surface, then the prediction is as follows.…”

“…A single polymer on a surface, although it may never desorb, can diffuse on this surface. This diffusion has been studied, and found to be much slower than in the bulk of the solution [29][30][31] .…”

Signal Oscillation Is Another Reason for Variability in Microarray-Based Gene Expression Quantification

“…Furthermore, lower surface-to-solution diffusivity ratio of target DNA improves signal-to-noise ratio. Since 2D diffusivity depends on polymer length much strongly than the solution diffusivity [54], transcripts of longer length may improve resolution. Although for measurement of ratios of the same transcript under different treatment conditions its length may not be important, for comparison of amounts of different transcripts including splice variants the signal intensity should be corrected for difference in transcript length.…”

Unexpected crossover dynamics of single polymer in a corrugated tube

“…A similar behavior is also observed for the diffusion of a single polymer chain adsorbed on solid surface. 28 While the cross-over scalings are always of great interest, it is yet imperative to understand the molecular origin of the behavior, which is directly accessible in molecular dynamics simulations. As of the N −1 scaling at large values of N, an expected argument would be that polymers may move as uncorrelated domains and thus lead to Rouse dynamics.…”