Phenoxyalkyl acrylates and methacrylates were studied as quenching (capping) agents for living carbocationic polymerization of isobutylene (IB) at −70°C in 40/60 (v/v) hexane/methyl chloride, catalyzed by TiCl 4 . Quenching reactions were carried out by reactivation by TiCl 4 of preformed difunctional tert-chloride-terminated polyisobutylene (PIB) or by a one-step method in which IB polymerization and quenching were conducted sequentially in the same reactor. Chain-end concentrations ranged from 0.02 to 0.1 M, and quenchers were used at concentrations of 1.5−2.5 times the chain ends. The phenoxyalkyl (meth)acrylates were synthesized by reaction of (meth)acryloyl chloride with the corresponding phenoxyalkanol; alkylene tethers from two to eight carbons were examined. Quenched polymers were characterized by 1 H and 13 C NMR, MALDI-TOF mass spectrometry, and size exclusion chromatography (SEC). Alkylation was observed to occur exclusively at the para position of the phenoxy moiety, and SEC showed no coupling or molecular weight degradation as a result of quenching. For short tethers of two or three carbons, quenching was slow and incomplete due to competing loss of living chain ends presumably by carbocation rearrangement. For tethers of four, six, or eight carbons, quenching was much faster and yielded quantitative (meth)acrylate chain-end functionality (number-average functionality ≥1.98 by 1 H NMR). MALDI-TOF-MS results were consistent with the expected end group structures. The carbonyl group of the quencher consumes one equivalent of Lewis acid in formation of a 1:1 complex; thus, the highest rate of quenching at a given Lewis acid concentration is achieved by using only a modest excess of quencher relative to living chain ends. P olyisobutylene (PIB) macromonomers and telechelic polymers possessing (meth)acrylate end groups are of great scientific and technological interest for the preparation of graft copolymers, 1 amphiphilic conetworks, 2−5 and various UV and/or thermally cured networks for sealants, encapsulants, adhesives, and coatings. 6,7 PIB is advantageous in these applications due to its low-temperature flexibility, adhesive strength, exceptional gas-barrier and energy damping properties, chemical, thermal, and oxidative stability, and biocompatibility. 3 The aim of this work was to develop a single-step synthesis of telechelic PIB (meth)acrylates using direct end quenching of living PIB. In the past, PIB (meth)acrylates have been synthesized by reaction of (meth)acryloyl chloride with primary hydroxyl-terminated PIB (PIB-OH) 1,8,9 or by reaction of alkali metal (meth)acrylates with primary bromine-terminated PIB (PIB-Br). 6,7,10−12 The PIB-OH routes involve either exo-olefin-or allylterminated PIB as an intermediate. In the 1980s, PIBs carrying tert-chloride end groups became available via the inifer method 13 and were converted to the exo-olefin derivatives by dehydrochlorination using potassium tert-butoxide. 14,15 More recently, exo-olefin-terminated PIB has been obtained by endquenching livi...

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Thiol‐terminated polysulfides (PS) are cured by mixing with an oxidant, resulting in limited shelf‐ and/or pot‐life, depending on whether formulated as a one‐ or two‐component system. Mixtures of thiol‐ and alkene‐terminated polysulfides offer the potential for an on‐demand curing process through thiol–ene photopolymerization. Thiol end groups of commercial polysulfides, PS‐1 (1000 g/mol) and PS‐2 (3000 g/mol), were converted to alkene by reaction with (meth)allyl bromide. Photopolymerizations were performed by irradiating films of equimolar thiol:ene mixtures at 320–500 nm (30 mW/cm2) in the presence of 5 wt % 2,2‐dimethoxy‐2‐phenyl‐acetophenone (DMPA). Reaction kinetics were measured using real‐time FTIR by monitoring absorbances at 3075 cm−1 (alkene) or 2550 cm−1 (thiol). In the absence of any reactive diluent, mixtures of thiol and alkene polysulfides failed to gel notwithstanding high reaction conversion (>90%). Partial or total replacement of the thiol polysulfide component with pentaerythritol tetrakis(3‐mercaptopropionate) (PETMP) yielded solid elastomeric films and ultimate reaction conversions of 80–96% after 5 min irradiation. Crosshatch adhesion measured on glass, aluminum, and steel was very poor (0B) for (meth)allyl PS‐1/PETMP and poor (2B) for (meth)allyl PS‐2/PETMP without adhesion promoters. (3‐Mercaptopropyl)trimethoxysilane (1 wt %) significantly improved adhesion of (meth)allyl PS‐2/PETMP on all substrates (4B) but yielded no improvement for (meth)allyl‐terminated PS‐1/PETMP. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45523.

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