An inorganic–organic hybrid CQDs@PVP lubricant additive: Achieving low friction and wear in PEG and water

High-temperature lubrication has always been a hot topic in the lubricant and grease industry, and is
also an essential concern in the high-end equipment sector to be addressed. Carbon quantum dots (CQDs)
are an emerging material widely applied in the field of lubrication, owing to their exceptional lubricity and
high load-bearing capacity. However, the vulnerability of CQDs to oxidation in air and reduced stability
dramatically restrict their high-temperature application capability. In this study, a nanocomposite of amphiphilic
polyvinyl pyrrolidone (PVP) homopolymer with excellent lubricating properties and thermal stability, which is
hydrogen bonded to CQDs (CQDs@PVP), was designed to achieve low friction and wear of lubricants at high
temperatures. The CQDs@PVP are consistently dispersed in both PEG400 and water, and exhibit superior
lubricity compared to unmodified CQDs at high temperatures (ranging from 200‒150 °C and 90‒50 °C).
Meanwhile, the dense carbon film on the wear surface and the chemically reactive film of iron compounds
directly contribute to the enhanced lubrication performance. These analytical results demonstrate the powerful
candidacy of CQDs@PVP as a lubrication additive and promote future high-temperature applications of CQDs
in industrial production.

高温润滑始终是润滑油与润滑脂行业的研究热点，同时也是高端装备领域亟待攻克的关键课题。碳量子点（CQDs）作为一类新兴材料，因其出色的润滑性能与高承载能力，被广泛应用于润滑领域。但碳量子点易在空气中氧化，且稳定性欠佳，极大限制了其高温应用能力。本研究设计了一种经氢键与碳量子点结合的两亲性聚乙烯吡咯烷酮（PVP）均聚物纳米复合材料（CQDs@PVP），该材料兼具优异润滑性能与热稳定性，可实现润滑剂在高温环境下的低摩擦与低磨损。CQDs@PVP可稳定分散于聚乙二醇400（PEG400）与水中，且在200‒150 ℃与90‒50 ℃的高温环境下，其润滑性能优于未改性的碳量子点。与此同时，磨损表面形成的致密碳膜与铁基化合物的化学反应膜，是润滑性能提升的直接成因。上述分析结果证实，CQDs@PVP作为润滑添加剂具备极强的应用潜力，可为碳量子点在工业生产中的高温应用推广提供有力支撑。