Polyisobutylene (PIB) bearing covalently bound antioxidants is reported. TiCl4-catalyzed cleavage/alkylation reactions were conducted on poly(isobutylene-co-isoprene) (EXXON (R) Butyl 068; M over bar n = 3.37 x 10(5) g/mol, () = 1.29, and 1.08 mol % isoprene) at -70 degrees C in 60/40 hexane/dichloromethane in the presence of 2,6-di-tert-butylphenol (DTP). Resulting PIB M over bar n s ranged from 30,000 to 85,300 g/mol and number average DTP functionalities (F-n) ranged from 4.3 to 12.0. H-1 NMR showed that 25%-40% of the DTP moieties underwent de-tert-butylation to form mono-tert-butyl phenol moieties. DTP-functionalized and nonfunctionalized control PIBs were subjected to thermogravimetric analysis in nitrogen and in air. In nitrogen, commercial control PIBs (olefinic end groups) showed delayed onset of thermal degradation (T-10 = 380-381 degrees C) relative to both control PIBs produced by living polymerization (tert-chloride end groups) and DTP-functionalized PIBs (T-10's all within the range of 366-370 degrees C). All PIBs showed lower degradation temperatures in air compared to nitrogen. Various control PIBs suffered 90% weight loss in air at temperatures ranging from 372 degrees C to 410 degrees C; DTP-functionalized PIBs did not suffer 90% weight loss in air until 412-414 degrees C. Oxidative induction time analysis showed that all control PIBs suffered catastrophic degradation within 6 min, and most within 1 min, but DTP-functionalized PIBs resisted degradation for >100 min. (c) 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019