Polyisobutylene (PIB) phenol (meth)­acrylates were produced by reacting di- or triphenol-terminated PIB with (meth)­acryloyl chloride. 1H NMR, GPC, and MALDI-TOF MS characterization showed that meth­(acrylate) end-functionality was 2 and 3, respectively, and that targeted molecular weights and relatively low polydispersities were achieved. Comparative aliphatic PIB triol triacrylate was prepared by end-quenching living polyisobutylene with 4-phenoxy-1-butyl acrylate. A photopolymerization study of PIB diphenol di­(meth)­acrylates with M n about 3000 g/mol, PIB triphenol tri­(meth)­acrylates with M n about 4000 and 10 000 g/mol, and control aliphatic PIB triol triacrylate with M n about 10 000 g/mol was conducted. Darocur 1173 and Irgacure 819 and 651 photoinitiators were studied, and FTIR reaction monitoring showed that Darocur 1173 afforded the highest rate of photopolymerization and final conversion, apparently due to its higher solubility in PIB. At M n ≅ 4000 g/mol, the rate of photopolymerization and conversion of PIB triphenol triacrylate was faster than that of PIB triphenol methacrylate under the same conditions; at M n ≅ 10 000 g/mol, PIB triphenol triacrylate, PIB triphenol trimethacrylate, and aliphatic PIB triacrylate all showed the same high rate of photopolymerization, which was higher than any rate observed at M n ≅ 4000 g/mol. Similarly, PIB triphenol tri­(meth)­acrylate at M n ≅ 4000 g/mol displayed a higher rate of photopolymerization and double-bond conversion than PIB diphenol di­(meth)­acrylate at M n ≅ 3000 g/mol, although they have similar chain end concentrations. This phenomenon was attributed to reduced diffusional mobility at higher M n, resulting in decreased rate of bimolecular radical termination and autoacceleration. T g of UV-cured PIB networks decreased as M n of PIB macromer increased regardless of end-group type, and thermal stability of cured networks remained constant regardless of end-group type. Mechanical properties were characteristic of rubbery networks, but weak, apparently due to low M n and low PDI of the starting macromers and lack of chain entanglements. Networks from macromers with M n ≅ 10 000 g/mol gave higher elongations, but lower Young’s moduli, compared to those from macromers with M n ≅ 4000 g/mol.

The Ritter reaction, that is, reaction of a carbocation with a nitrile, was carried out on polyisobutylene (PIB) using a variety of reaction conditions. End quenching of PIB carbocations with acrylonitrile under living polymerization conditions (methyl chloride (MeCl)/hexane 60/40 (v/v) solvent mixtures at 270 8C) resulted in either tert-chloride end groups or loss of chain-end fidelity via carbocation rearrangement, as evidenced by NMR spectroscopy. Exo-olefin functionalized PIB substrates were also reacted with nitriles under a variety of reaction conditions including various acid and solvent medium combinations. In all cases, the result was either no reaction or PIB that had undergone severe backbone degradation, as determined via NMR spectroscopy and gel permeation chromatography. Finally, the Ritter reaction was performed on a series of exo-olefin functionalized oligoisobutylenes using acrylonitrile as the nitrile and either 60/40 dichloromethane/hexane or excess acrylonitrile as the solvent. In 60/40 dichloromethane/hexane, significant carbocation rearrangement and/or degradation resulted in a variety of isomeric, acrylamide-functionalized oligomers. In excess acrylonitrile, the desired Ritter reaction was the only reaction observed, resulting in the smooth formation of the terminal acrylamide. The various N-oligoisobutylacrylamides thus obtained represent new hydrophobic monomers useful for the introduction of hydrophobic moieties into acrylamide-based water-soluble polymers.

Polyisobutylene (PIB) bearing covalently bound antioxidants is reported. TiCl4‐catalyzed cleavage/alkylation reactions were conducted on poly(isobutylene‐co‐isoprene) (EXXON® Butyl 068; normalMfalse¯n = 3.37 × 105 g/mol, (Ð) = 1.29, and 1.08 mol % isoprene) at −70 °C in 60/40 hexane/dichloromethane in the presence of 2,6‐di‐tert‐butylphenol (DTP). Resulting PIB normalMfalse¯n s ranged from 30,000 to 85,300 g/mol and number average DTP functionalities (Fn) ranged from 4.3 to 12.0. 1H 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 (T10 = 380–381 °C) relative to both control PIBs produced by living polymerization (tert‐chloride end groups) and DTP‐functionalized PIBs (T10's all within the range of 366–370 °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 °C to 410 °C; DTP‐functionalized PIBs did not suffer 90% weight loss in air until 412–414 °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. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1836–1846

Linear, multi‐functional polyisobutylene (PIB) macromers bearing pendent and terminal (meth)acrylate moieties were prepared via electrophilic cleavage/alkylation of butyl rubber in the presence of (3‐bromopropoxy)benzene, followed by displacement of the resulting bromide moieties with potassium (meth)acrylate. Number average functionality (Fn) ranged from 2.8–7.9; functional equivalent weights ranged from 2.3–4.7 kg/mol. For comparison, a three‐arm, end‐functional PIB triacrylate with equivalent weight of 3.3 kg/mol was also synthesized via living polymerization and end quenching with 4‐phenoxy‐1‐butyl acrylate. All polymers were photocured using Darocur 1173 photoinitiator, and curing kinetics were monitored by real time Fourier‐transform infrared spectroscopy. All systems reached ~100% conversion by 1,800 s, but the linear macromers displayed slower curing rates compared to the PIB triacrylate. The curing rate of linear macromers increased as molecular weight decreased. Cured networks were characterized using dynamic mechanical analysis and tensile testing. Tensile strength varied from 0.15–0.80 MPa. Young's modulus varied from 0.13–1.8 MPa. Strain at break for most networks ranged from 34–54%, but the network derived from the lowest molecular weight PIB reached 113% at failure. Percent extractables, measured using solvent extraction, was about 2% for linear macromers and about 4% for PIB triacrylate.