Open AccessPoly(ethylene glycol)s in Semidilute Regime: Radius of Gyration in the Bulk and Partitioning into a Nanopore
Author(s) -
Philip A. Gurnev,
Christopher B. Stanley,
M. Alphan Aksoyoglu,
Kwangjoon Hong,
V. Adrian Parsegian,
Sergey M. Bezrukov
Publication year - 2017
Publication title -
macromolecules
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.994
H-Index - 313
eISSN - 1520-5835
pISSN - 0024-9297
DOI - 10.1021/acs.macromol.6b02571
Subject(s) - nanopore , radius of gyration , polymer , ethylene glycol , peg ratio , gyration , neutron scattering , polymer chemistry , chemical physics , conductance , materials science , chemistry , chemical engineering , hydrodynamic radius , analytical chemistry (journal) , scattering , nanotechnology , chromatography , organic chemistry , physics , optics , copolymer , geometry , mathematics , finance , condensed matter physics , engineering , economics
Using two approaches, small-angle neutron scattering (SANS) from bulk solutions and nanopore conductance-fluctuation analysis, we studied structural and dynamic features of poly(ethylene glycol) (PEG) water/salt solutions in the dilute and semidilute regimes. SANS measurements on PEG 3400 at the zero-average contrast yielded the single chain radius of gyration ( R g ) over 1-30 wt %. We observed a small but statistically reliable decrease in R g with increasing PEG concentration: at 30 wt % the chain contracts by a factor of 0.94. Analyzing conductance fluctuations of the α -hemolysin nanopore in the mixtures of PEG 200 with PEG 3400, we demonstrated that polymer partitioning into the nanopore is mostly due to PEG 200. Specifically, for a 1:1 wt/wt mixture the smaller polymer dominates to the extent that only about 1/25 of the nanopore volume is taken by the larger polymer. These findings advance our conceptual and quantitative understanding of nanopore polymer partitioning; they also support the main assumptions of the recent "polymers-pushing-polymers" model.