聚四氟乙烯Polytetrafluoroethylene

C–F 键能约 485 kJ/mol，是有机化学中最强的单键之一；体积较大的氟原子像紧密的外壳包住碳链，使链呈 13₆ 或 15₇ 螺旋构象，屏蔽了主链。氟的极化率很低，分子间作用力极弱，因此表面能极低（约 18 mN/m），不粘、不湿润，摩擦系数约 0.05–0.10。PTFE 熔点约 327 °C，但熔体黏度极高（约 10¹⁰ Pa·s），不能熔融注塑，只能用类似粉末冶金的压制-烧结法加工。

The C–F bond (about 485 kJ/mol) is among the strongest single bonds in organic chemistry, and the larger fluorine atoms sheath the carbon chain, twisting it into a 13₆ or 15₇ helix that shields the backbone. Fluorine's low polarisability makes intermolecular forces very weak, so the surface energy is very low (about 18 mN/m), nothing sticks or wets it, and the friction coefficient is about 0.05–0.10. PTFE melts near 327 °C, but its melt viscosity is enormous (about 10¹⁰ Pa·s), so it cannot be injection moulded and is shaped by pressing and sintering, like powder metallurgy.

1938 年 4 月，杜邦公司的罗伊·普朗克特在研究新型制冷剂时，打开一瓶储存的四氟乙烯气体，发现没有气体放出，锯开钢瓶后发现内壁有白色蜡状粉末，这就是自发聚合生成的聚四氟乙烯。二战期间它被曼哈顿计划用于制作耐六氟化铀腐蚀的密封件。1945 年以 Teflon 商标注册，1954 年法国的格雷瓜尔发明不粘锅。

In April 1938 Roy Plunkett at DuPont, working on new refrigerants, opened a cylinder of stored tetrafluoroethylene and found no gas came out; cutting it open revealed a white waxy powder, PTFE formed by spontaneous polymerisation. In the Second World War the Manhattan Project used it for seals resistant to uranium hexafluoride. It was registered as Teflon in 1945, and Marc Grégoire in France invented the non-stick pan in 1954.

PTFE 用于不粘锅涂层、化工管道衬里和阀门密封、实验室搅拌子、高频电缆绝缘、人工血管、膨体 PTFE 防水透气面料（Gore-Tex）和生料带。过去生产 PTFE 使用全氟辛酸（PFOA）作乳化剂，PFOA 环境持久、可在人体蓄积，已被《斯德哥尔摩公约》列入淘汰名单。PTFE 本身无毒，但在 350 °C 以上分解会释放有毒含氟气体。

PTFE is used for non-stick coatings, linings and seals in chemical plant, laboratory stir bars, high-frequency cable insulation, vascular grafts, expanded-PTFE breathable waterproof fabric (Gore-Tex) and thread-seal tape. Its manufacture once used perfluorooctanoic acid (PFOA) as an emulsifier; PFOA is persistent and bioaccumulative and is being phased out under the Stockholm Convention. PTFE itself is non-toxic, but above about 350 °C it decomposes to toxic fluorinated gases.