The degradation characteristics of perfluoropolyether(PFPE) for computer hard disk drive have been investigated. Thermal degradation in PFPE started at 170 ℃ and it was completed at 450 ℃. If PFPE was contacted with wear fragment from slider made by Al2O3ㆍTiC, the thermal degradation was accelerated by the catalytic Lewis acid degradation. The Lewis acid degradation mainly took placed in methylene oxide(fluoride) chain scission as well as methylene(fluoride) and hydroxy end chain. As a result, the degradation reaction accomplished as early as at 300 ℃. The photo oxidation due to UV exposure on PFPE caused the chain scission in methylene(fluoride), and end chain in PFPE without chain scission in methylene oxide(fluoride) and then the molecular weight of PFPE increased by expected secondary reactions between formed radicals in the photo oxidation.

컴퓨터 하드디스크 윤활제로 사용되고 있는 perfluoropolyether(PFPE)의 다양한 분해 거동을 살펴보았다. PFPE의 열분해는 170 ℃에서 시작하여 450 ℃에서 완전 분해가 일어나며 마모된 하드디스크 슬라이드의 재질인 Al2O3ㆍTiC가 윤활제와 접촉하는 경우, Lewis acid 촉매분해에 의하여 주사슬의 methylene oxide(fluoride)의 절단에 의한 급격한 분해반응과 methylene(fluoride)와 hydroxy 말단기의 열분해로 인하여 300 ℃에서 분해가 완료됨을 확인하였다. PFPE에 UV가 조사되면 광 분해 영향으로 Lewis acid 촉매분해와는 달리 methylene oxide (fluoride)의 절단 보다는 methylene(fluoride)와 말단기의 절단이 더 촉진되며 이때 생성된 라디칼의 2차 반응에 의한 chain extension에 의하여 PFPE의 분자량이 증가됨을 확인하였다.

Keywords: perfluoropolyether; lubricant; hard disk drive; Lewis acid degradation; UV degradation