Work

Low-Temperature Performance and Tribological Properties of Poly(5-n-butyl-2-norbornene) Lubricating Oils: Effect of Molecular Weight and Hydrogenation on the Viscosity and Anti-Wear Activity

Year: 2025

Type: article

Abstract: A series of poly(5-n-butyl-2-norbornene) oils with controlled molecular weights was synthesized via metathesis polymerization, fully hydrogenated, and characterized in terms of viscosity and tribological performance. In contrast to established lubricant base stocks—such as poly(α-olefins) and multiply alkylated cyclopentanes—these novel norbornene-based polymers remain underexplored, despite their promising anti-wear activity. Based on differential scanning calorimetry (DSC) data, all the synthesized products are amorphous compounds whose thermograms show a single glass transition temperature. The effect of molecular weight and temperature on the viscosity of poly(5-n-butyl-2-norbornene) oils was quantified over an extended temperature range, including extra-cold conditions down to −80 °C. The pour points of the oils were determined and can be as low as −66 °C, indicating excellent low-temperature fluidity. The tribological performance of the synthesized oils was evaluated using the four-ball test, with friction coefficient and wear scar diameter measured to assess anti-wear and antifriction properties. The tribological results were benchmarked against commercially available polyalphaolefin (PAO) oils (PAO-4, PAO-20, and PAO-80). Metathesis and hydrogenated poly(5-n-butyl-2-norbornene) oils outperform conventional PAOs by up to 67% in wear protection and 30% in friction reduction. These findings establish alicyclic molecular strain as a viable design parameter for next-generation lubricating oils, thereby expanding the toolbox for material development beyond conventional chemical functionalization.

Source: Polymers

DOI: 10.3390/polym17243333

Authors: Valeriia R. Nazemutdinova, Sergey O. Ilyin, Aleksandr A. Morontsev, Igor S. Makarov, Alyona I. Wozniak, Maxim V. Bermeshev

Institutions: Russian Academy of Sciences, A.V. Topchiev Institute of Petrochemical Synthesis, Institute of Synthetic Polymeric Materials

Language: English

Topic: Lubricants and Their Additives

Subfield: Mechanical Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $3,258

Funders: Russian Science Foundation, Russian Academy of Sciences