Micellization and Adsorption to Carbon Black of Polyisobutylene-Based Ionic Liquids

Document Type

Article

Publication Date

1-15-2020

School

Polymer Science and Engineering

Abstract

Ionic liquid‐terminated polyisobutylene (PIB‐IL) dispersants suitable for stabilization of carbonaceous deposits found in automotive lubricating oils were derived by the quaternization of tertiary amines (1‐methyl‐imidazole, pyridine, and isoquinoline) with primary bromide‐terminated PIB. Characterization of PIB intermediate and PIB‐IL dispersants was carried out by nuclear magnetic resonance, gel‐permeation chromatography, thermogravimetric analysis (TGA), matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry, and differential scanning calorimetry. PIB‐IL micellization in dodecane and characteristics thereof (hydrodynamic radius, aggregation number, and critical micelle concentration) were investigated by static (SLS) and dynamic light scattering; whereupon, the self‐association of PIB‐IL was found to be highly sensitive to anion hydrophobicity. Qualitative adsorption of PIB‐IL onto carbon black was confirmed by Fourier transform infrared and TGA measurements. Using Langmuir adsorption studies, the affinity for and adsorption to carbon black of PIB‐IL were characterized. PIB‐IL adsorption onto carbon black occurred via cation–π interactions and was identified to be highly dependent on the molar volume of the cation and independent of the anion. From the parameters obtained by the Langmuir adsorption isotherms, the spatial arrangement of PIB‐IL on the carbon black surface was elucidated, in which all adsorbed PIB‐IL were determined to exist in the elongated brush regime.

Publication Title

Journal of Polymer Science

Volume

58

Issue

2

First Page

280

Last Page

299

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