Abstract
We report novel polymeric materials that may be used as viscosity index improvers (VII) for lubricant applications. Our efforts included probing the comb-burst hyper-branched aryl polyester architecture for beneficial viscosity and friction behavior when utilized as an additive in a group I oil. The monomer was designed as to undergo polymerization via polycondensation within the architectural construct (AB 2), typical of hyperbranched polymers. The monomer design was comprised of aliphatic arms (12 or 16 methylenes) to provide the necessary lipophilicity to achieve solubility in a non-polar medium. Once polymerized, via catalyst and heat, the surface alcohols were functionalized with fatty acids (lauric and palmitic). Controlling the aliphatic nature of the internal arms and peripheral end-groups provided four unique flexible polymer designs. Changing the reaction time and concentration provided opportunities to investigate the influence of molecular weight and branching density on oil-solubility, viscosity, and friction. Oil-solubility was found to decrease with fewer internal carbons, but the number of internal carbons appears to have little influence on the bulk solution viscosity. At concentrations of 2 wt % in a group I base oil, these polymer additives demonstrated an improved viscosity index and reduced friction coefficient, validating the basic approach.
Original language | English |
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Article number | 18624 |
Journal | Scientific Reports |
Volume | 6 |
DOIs | |
State | Published - Jan 5 2016 |
Funding
This project was funded by the Office of Vehicle Technology (VT) of the U.S. Department of Energy (US DOE), (under contract No. 27573). A portion of this research was performed using EMSL, a national scientific user facility sponsored by the Department of Energy’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. PNNL is proudly operated by Battelle for the U.S. DOE (under Contract DE_ AC06–76RLO 1830). The authors cordially acknowledge contributions from Erin Baker (PNNL) for performing electrospray ionization mass spectrometry and helpful discussions with Ewa Bardasz (Energetics) and Bruce Bunting (Energetics). The authors would like to express their gratitude to David Gray (Evonik) and JoRuetta Ellington (Evonik) for their technical assistance and guidance throughout the project. We thank Afton Chemical for generously donating base oils for screening purposes.