{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T05:04:01Z","timestamp":1787029441232,"version":"build-2736575974"},"reference-count":36,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2026,2,20]],"date-time":"2026-02-20T00:00:00Z","timestamp":1771545600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100021171","name":"Guangdong Basic and Applied Basic Research Foundation","doi-asserted-by":"crossref","award":["2022A1515110306"],"award-info":[{"award-number":["2022A1515110306"]}],"id":[{"id":"10.13039\/501100021171","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Polymers"],"abstract":"<jats:p>In low Earth orbit (LEO), special environments such as atomic oxygen (AO), alternating high and low temperatures, and high vacuum can seriously affect the reliability and service lifetime of moving parts of space equipment. Therefore, there is an increasingly urgent demand for long-life, high-performance lubricating protective coatings with the rapid evolution of astronautical technology. In this study, polyimide (PI) was modified by polyhedral oligomeric silsesquioxane (POSS) with different numbers of functional groups to fabricate PI-based self-stratifying gradient composite lubricating coatings. The coating exhibited significantly enhanced AO resistance, and its vacuum tribological properties under alternating high and low temperature conditions were investigated. Results show that the mass loss of the gradient coating under AO exposure was significantly reduced by 78%, and the tribological properties of the coating under high and low temperature alternating conditions were significantly different. The friction coefficient was more stable and was smaller than that at high temperatures, and the wear rates of the POSS-modified coating also decreased by 77.5% and 50% for both high and low temperatures compared with that of the PI\/PTFE coating.<\/jats:p>","DOI":"10.3390\/polym18040521","type":"journal-article","created":{"date-parts":[[2026,2,20]],"date-time":"2026-02-20T10:32:37Z","timestamp":1771583557000},"page":"521","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Spatial Tribological Properties of PI\/PTFE Based Self-Stratifying Composite Coatings Grafted by Amino-POSS"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0308-5471","authenticated-orcid":false,"given":"Chuanyong","family":"Yu","sequence":"first","affiliation":[{"name":"School of Mechatronic Engineering and Automation, Foshan University, Foshan 528225, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3258-2159","authenticated-orcid":false,"given":"Min","family":"Wei","sequence":"additional","affiliation":[{"name":"School of Mechatronic Engineering and Automation, Foshan University, Foshan 528225, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qiwei","family":"Wang","sequence":"additional","affiliation":[{"name":"Institute of Advanced Wear & Corrosion Resistant and Functional Materials, Jinan University, Guangzhou 510632, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wei","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Mechatronic Engineering and Automation, Foshan University, Foshan 528225, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,2,20]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"613","DOI":"10.1007\/s12567-020-00323-7","article-title":"A cutting edge 6U CubeSat ADCS design for Earth observation with sub-meter spatial resolution at 230\u2013380 km altitude","volume":"12","author":"Kuiper","year":"2020","journal-title":"CEAS Space J."},{"key":"ref_2","first-page":"10","article-title":"Mission for Super-Low Earth Orbit, SLATS","volume":"198","author":"Sasaki","year":"2017","journal-title":"Space Res. 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