Boundary Lubrication of PEO-PPO-PEO Triblock Copolymer Physisorbed on Polypropylene, Polyethylene, and Cellulose Surfaces

Yangyang Li, O. J. Rojas, J. P. Hinestroza*

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    27 Citations (Scopus)

    Abstract

    In situ lateral force microscopy (LFM) and X-ray photoelectron spectroscopy (XPS) were used to probe the lubrication behavior of an aqueous solution of poly(oxyethylene)-poly(oxypropylene)-poly(oxyethylene) (PEO-PPO-PEO) symmetric triblock copolymer on thin films of polypropylene (PP), polyethylene (PE), and cellulose. LFM experiments were carried out while the substrates were immersed in water and in solutions of the copolymer. The friction coefficient on PP and PE was reduced after adsorption from the PEO-PPO-PEO aqueous solution while the opposite effect was observed for cellulose surfaces. A critical normal loading force, at which the friction coefficient of the lubricated and unlubricated surfaces is equal, was identified and related to the affinity of the polymer with the substrate. Further experiments were performed to mimic practical operations involving lubricant addition during manufacturing and postprocessing removal. XPS was used to verify the presence of the lubricant on the polymeric substrates and to evaluate its removal by water washing. The lubricant layer was easily removed by water from the PP and cellulose surfaces while a durable layer was found on PE. The XPS results were in agreement with the highest critical normal loading force measured for PE (52 nN for PE in contrast to a minimum of 10 nN for cellulose). While several reports exist on lubrication on hard surfaces, friction behavior on soft surfaces is still not well documented as the substrates usually deform under loading pressure. Therefore, we also propose a simple lubrication model for PP, PE, and cellulose and the use of critical normal loading force as a parameter to predict lubricity and durability of adsorbed nonionic block copolymers.

    Original languageEnglish
    Pages (from-to)2931-2940
    Number of pages10
    JournalIndustrial and Engineering Chemistry Research
    Volume51
    Issue number7
    DOIs
    Publication statusPublished - 22 Feb 2012
    MoE publication typeA1 Journal article-refereed

    Keywords

    • ATOMIC-FORCE MICROSCOPY
    • SELF-ASSEMBLED MONOLAYERS
    • SYNTHETIC-FIBERS
    • INTERFACIAL FRICTION
    • ADSORPTION
    • FILMS
    • THIN
    • SURFACTANTS
    • ROUGHNESS
    • GRAPHITE

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