Effect of Salt on Phosphorylcholine-based Zwitterionic Polymer Brushes

Zhang, Zhenyu J.; Moxey, Mark; Alswieleh, Abdullah M.; Morse, Andrew J.; Lewis, Andrew L.; Geoghegan, Mark; Leggett, Graham

doi:10.1021/acs.langmuir.6b00763

Cited by 83 publications

(84 citation statements)

References 62 publications

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“…A linear friction-load relationship was not observed for any salt at the concentrations used in this work for either experimental geometry. A similar phenomenon was reported in recent work on the effect of salt on the frictional properties of poly[2-(methacryloyloxy)-ethyl phosphorylcholine] (PMPC) which is highly lubricious and generally displayed a linear friction-load relationship [40]. In that particular study, KI was determined to have a larger coefficient of friction than KBr, but that is due to the nature of the interaction between halide anions and the functional groups.…”

Section: Discussionsupporting

confidence: 84%

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Salt Dependence of the Tribological Properties of a Surface-Grafted Weak Polycation in Aqueous Solution

et al. 2017

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The nanoscopic adhesive and frictional behaviour of end-grafted poly[2-(dimethyl amino)ethyl methacrylate] (PDMAEMA) films (brushes) in contact with gold-or PDMAEMA-coated atomic force microscope tips in potassium halide solutions with different concentrations up to 300 mM is a strong function of salt concentration. The conformation of the polymers in the brush layer is sensitive to salt concentration, which leads to large changes in adhesive forces and the contact mechanics at the tip-sample contact, with swollen brushes (which occur at low salt concentrations) yielding large areas of contact and friction-load plots that fit JKR behaviour, while collapsed brushes (which occur at high salt concentrations) yield sliding dominated by ploughing, with conformations in between fitting DMT mechanics. The relative effect of the different anions follows the Hofmeister series, with I − collapsing the brushes more than Br − and Cl − for the same salt concentration.

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Section: Discussionsupporting

confidence: 84%

“…Recent work has shown that there is a low adhesion regime whereby single asperity contact mechanics is insufficient to describe the interaction of a polymer brush with an AFM tip [11,12,[39][40][41][42][43][44]. The AFM tip can reasonably be considered as a single asperity probe given its small radius.…”

Section: Introductionmentioning

confidence: 99%

Salt Dependence of the Tribological Properties of a Surface-Grafted Weak Polycation in Aqueous Solution

et al. 2017

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“…Zwitterionic polymers, which contain both anionic groups and cationic groups along their molecular chains, play an important role in oil recovery, seawater desalination, sewage treatment, and biomaterials, enhancing their performance in saline water . For polyzwitterions, ionic groups can be either divided into different monomer units or concentrated in the same monomer unit.…”

Section: Introductionmentioning

confidence: 99%

Solution behavior of water‐soluble poly(acrylamide‐co‐sulfobetaine) with intensive antisalt performance as an enhanced oil‐recovery chemical

Zhang

Gou

Zhao

et al. 2018

J of Applied Polymer Sci

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In the process of oilfield development, salt tolerance is an important property for enhanced oil‐recovery (EOR) chemicals. In this study, we synthesized two acrylamide‐based sulfobetaine copolymers containing 2‐hydroxy‐3‐[(3‐methacrylamidopropyl)dimethylammonio]propane sulfonate (SHPP) or 3‐(4‐acry‐loyl‐1‐methyl‐piperazinio)‐2‐hydroxypropane sulfonate (SHMP). The interactions between these two copolymers and inorganic salts were compared, and the apparent viscosity (ηapp) behaviors of copolymer–salt solutions at different shear rates and temperatures were investigated. We found that the ηapp of PAPP and PAMP showed intensive antisalt performance, exhibiting an excellent antipolyelectrolyte effect. The ηapp retention value of 30,000 mg/L PAMP in brine was 86.47 mPa s at 510 s−1, and when the temperature was increased to 90 °C, it was 99.73 mPa s; this was better than that of PAPP under the same conditions. Therefore, PAMP was more applicable as an EOR chemical that have outstanding salt tolerance and temperature resistance. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46235

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“…This effect can be mimicked by end-anchoring polymers to surfaces to form so-called polymer brushes [4]. With these brushes, effective and durable lubricants have been developed that can work under aqueous [5,6] as well as oil environments [7].…”

Section: Introductionmentioning

confidence: 99%

Polymer Brush Friction in Cylindrical Geometries

2019

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Polymer brushes are outstanding lubricants that can strongly reduce wear and friction between surfaces in sliding motion. In recent decades, many researchers have put great effort in obtaining a clear understanding of the origin of the lubricating performance of these brushes. In particular, molecular dynamics simulations have been a key technique in this scientific journey. They have given us a microscopic interpretation of the tribo-mechanical response of brushes and have led to the prediction of their shear-thinning behavior, which has been shown to agree with experimental observations. However, most studies so far have focused on parallel plate geometries, while the brush-covered surfaces might be highly curved in many applications. Here, we present molecular dynamics simulations that are set up to study the friction for brushes grafted on the exterior of cylinders that are moving inside larger cylinders that bear brushes on their interior. Our simulations show that the density distributions for brushes on the interior or exterior of these cylinders are qualitatively different from the density profiles of brushes on flat surfaces. In agreement with theoretical predictions, we find that brushes on the exterior of cylinders display a more gradual decay, while brushes on the interior of cylinders becomes denser compared to flat substrates. When motion is imposed, the density profiles for cylinder-grafted brushes adapt qualitatively differently to the shear motion than observed for the parallel plate geometry: the zone where brushes overlap moves away from its equilibrium position. Surprisingly, and despite all these differences, we observe that the effective viscosity is independent of the radius of the brush-grafted cylinders. The reason for this is that the viscosity is determined by the overlap between the brushes, which turns out to be insensitive to the exact density profiles. Our results provide a microscopic interpretation of the friction mechanism for polymer brushes in cylindrical geometries and will aid the design of effective lubricants for these systems.

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Effect of Salt on Phosphorylcholine-based Zwitterionic Polymer Brushes

Cited by 83 publications

References 62 publications

Salt Dependence of the Tribological Properties of a Surface-Grafted Weak Polycation in Aqueous Solution

Salt Dependence of the Tribological Properties of a Surface-Grafted Weak Polycation in Aqueous Solution

Solution behavior of water‐soluble poly(acrylamide‐co‐sulfobetaine) with intensive antisalt performance as an enhanced oil‐recovery chemical

Polymer Brush Friction in Cylindrical Geometries

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