Issue 10, 2020

Diffusion dynamics of a single collapsed homopolymer globule at the solid–liquid interface

Abstract

Contradictive to the conventional wisdom that a collapsed polymer globule in poor solvents adsorb on surfaces in a way analogous to the spreading of a liquid droplet, here we have shown via single molecule measurements that a single poly(N-isoporpylacrylamide) (PNIPAM) globule can jump from one spot to another as an elastic nonadhesive ball even on a hydrophobic polystyrene surface. The molecular weight dependence of the effective surface diffusion coefficient measured for the adsorbed globule suggested that it exhibited mostly a similar globular conformation to that in the bulk solution. Both the displacement and waiting time distributions of the adsorbed globules were found to follow a power-law decay rather than an exponential process, suggesting a broad distribution of binding energies due to the difference in degree of globule deformation. These effects together reflect a character of the viscoelasticity even in a single-chain globule in dilute solutions. Our findings also demonstrate that it is not the single-chain globule but the inter-globule aggregates at high concentration that lead to irreversible adsorption on the surface, which provides novel dynamics and mechanisms of how a thermosensitive polymer adsorbs on the hydrophobic surface above its lower critical solution temperature.

Graphical abstract: Diffusion dynamics of a single collapsed homopolymer globule at the solid–liquid interface

Associated articles

Article information

Article type
Paper
Submitted
26 Nov 2019
Accepted
06 Jan 2020
First published
06 Jan 2020

Soft Matter, 2020,16, 2431-2436

Diffusion dynamics of a single collapsed homopolymer globule at the solid–liquid interface

S. Cai, J. Liu, M. Tian, K. Wang and L. Shen, Soft Matter, 2020, 16, 2431 DOI: 10.1039/C9SM02335F

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