TY - JOUR
T1 - Adsorption properties of poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) at a hydrophobic interface: Influence of tribological stress, pH, salt concentration, and polymer molecular weight
AU - Lee, Seunghwan
AU - Spencer, Nicholas D.
PY - 2008
Y1 - 2008
N2 - The adsorption properties of a graft copolymer of poly(ethylene glycol) (PEG) with a polycationic backbone,
namely, poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG), onto nonpolar, hydrophobic PDMS surfaces from
aqueous solution and the lubrication properties of the self-mated sliding contacts of PDMS surfaces modified with
PLL-g-PEG have been investigated. Whereas PLL-g-PEG is spontaneously attracted to negatively charged surfaces
as a result of the polycationic PLL backbone, the collective interaction of (CH2)4 hydrocarbon moieties on the lysine
units in the PLL backbone with nonpolar, hydrophobic surfaces also enables the adsorption of PLL-g-PEG onto
hydrophobic surfaces such as PDMS. The adsorption and lubrication properties of PLL-g-PEG have been investigated
by varying the aqueous solution parameters, such as pH (2, 7, and 12) and KCl concentration (0, 0.01, 0.1, and 1 M)
as well as the length of the PLL backbone of the copolymer (20 vs 375 kDa). In the absence of tribological stress,
the adsorption of PLL-g-PEG onto PDMS surfaces was mainly governed by the KCl concentration, whereas the role
of pH or the molecular weight of the copolymer was of relatively minor importance; for all pH values, the adsorbed
mass decreased with increasing KCl concentration. Under tribological stress, however, a clear dependence of the
lubrication properties of PLL-g-PEG on all of the studied parameters, including pH, KCl concentration, and backbone
molecular weight, was observed. The adsorption strength of PLL-g-PEG on PDMS surfaces, rather than the adsorbed
mass itself, appeared to be the most critical parameter in determining the lubrication properties.
AB - The adsorption properties of a graft copolymer of poly(ethylene glycol) (PEG) with a polycationic backbone,
namely, poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG), onto nonpolar, hydrophobic PDMS surfaces from
aqueous solution and the lubrication properties of the self-mated sliding contacts of PDMS surfaces modified with
PLL-g-PEG have been investigated. Whereas PLL-g-PEG is spontaneously attracted to negatively charged surfaces
as a result of the polycationic PLL backbone, the collective interaction of (CH2)4 hydrocarbon moieties on the lysine
units in the PLL backbone with nonpolar, hydrophobic surfaces also enables the adsorption of PLL-g-PEG onto
hydrophobic surfaces such as PDMS. The adsorption and lubrication properties of PLL-g-PEG have been investigated
by varying the aqueous solution parameters, such as pH (2, 7, and 12) and KCl concentration (0, 0.01, 0.1, and 1 M)
as well as the length of the PLL backbone of the copolymer (20 vs 375 kDa). In the absence of tribological stress,
the adsorption of PLL-g-PEG onto PDMS surfaces was mainly governed by the KCl concentration, whereas the role
of pH or the molecular weight of the copolymer was of relatively minor importance; for all pH values, the adsorbed
mass decreased with increasing KCl concentration. Under tribological stress, however, a clear dependence of the
lubrication properties of PLL-g-PEG on all of the studied parameters, including pH, KCl concentration, and backbone
molecular weight, was observed. The adsorption strength of PLL-g-PEG on PDMS surfaces, rather than the adsorbed
mass itself, appeared to be the most critical parameter in determining the lubrication properties.
U2 - 10.1021/la801200h
DO - 10.1021/la801200h
M3 - Journal article
C2 - 18652428
SN - 0743-7463
VL - 24
SP - 9479
EP - 9488
JO - Langmuir
JF - Langmuir
IS - 17
ER -