Stannous octoate sn oct 2

Titanium tetrachloride (TiCl₄) (99%; Tokyo Chemical Industry Co.) were dried over phosphorus pentoxide (P₂O₅) under N₂ atmosphere for 12 hours before use, n-hexane (99.5%; Beijing Yanshan Petroleum Chemical Co.) were refluxed and distilled with sodium under N₂ atmosphere for 48 hours before use, 1,4-butadiene (BD) (99%; Beijing Yanshan Petroleum Chemical Co.) and isobutylene (IB) (99.9%; Beijing Yanshan Petroleum Chemical Co.) were condensed in a cold bath in a glove box prior to polymerization. 5-tert-Butyl-bis(2-methoxy-2-propyl)benzene (t-Bu-m-DiCuOMe) was prepared by 5-tert-butylisophthalic acid through grignard reaction. Methyl chloride (MeCl) (99%; Beijing Chemical Reagent Co.), commercial polyurethane (PU) (Pellethane5863, Lubrizol, Mn = 10 000 g mol⁻¹), 4,4′-methylenebis(phenyl isocyanate) (MDI) (97%; Tokyo Chemical Industry Co.), tetrabutylammonium hydroxide (TBAH) (27wt% solution in H₂O; Tokyo Chemical Industry Co.), stannous octoate ((Sn(Oct)₂) (95%; Tokyo Chemical Industry Co.), 1,4-butanediol (BDO) (99%; Tokyo Chemical Industry Co.), tetrahydrofuran (THF) (99.9%; Tokyo Chemical Industry Co.), 2,6-di-tert-butylpyridine (DtBP) (96%; Tokyo Chemical Industry Co.), methanol (99%; Beijing Chemical Reagent Co.), nitric acid (68%; Beijing Chemical Reagent Co.) were used as received.