Cationic polymerization of isobutylene in toluene: toward well-defined exo-olefin terminated medium molecular weight polyisobutylenes under mild conditions

Section: Synthesis Of Polyisobutylene and Isobutylene–isoprene Copolymentioning

confidence: 99%

“…). Because toluene is relatively weak base to coordinate with the growing cations, which primarily form the exo‐olefin end groups …”

Section: Synthesis Of Polyisobutylene and Isobutylene–isoprene Copolymentioning

confidence: 99%

Cationic half‐sandwich scandium complex for the synthesis of polyisobutylene with high molecular weight under mild conditions

Shen

et al. 2017

“…This was confirmed by the results of polymerization with water as the initiator in the presence or absence of impurities (Supporting Information Table S33–S36). In these experiments, water with EADC · CEE yields H + EADCOH − , which initiates the polymerization. By increasing the concentration of acetone, the polymerization rate decreases, and at [acetone] = [H 2 O] polymerization was absent.…”

Section: Resultsmentioning

confidence: 99%

Catalytic chain transfer polymerization of isobutylene: The role of nucleophilic impurities

Rajasekhar

Haldar

Emert

et al. 2017

Fast polymerization of isobutylene (IB) initiated by tert‐butyl chloride using ethylaluminum dichloride·bis(2‐chloroethyl) ether complex (T. Rajasekhar, J. Emert, R. Faust, Polym. Chem. 2017, 8, 2852) was drastically slowed down in the presence of impurities, such as propionic acid, acetone, methanol, and acetonitrile. The effect of impurities on the polymerization rate was neutralized by using two different approaches. First, addition of a small amount of iron trichloride (FeCl3) scavenged the impurity and formed an insoluble FeCl3··impurity complex in hexanes. The polymerization rate and exo‐olefin content were virtually identical to that obtained in the absence of impurities. Heterogeneous phase scavenger (FeCl3) exhibited better performance than homogenous phase scavengers. In the second approach, conducting the polymerization in wet hexanes, the fast polymerization of IB was retained in the presence of impurities with a slight decrease in exo‐olefin content. 1H NMR studies suggest that nucleophilic impurities are protonated in the presence of water, and thereby neutralized. Mechanistic studies suggest that the rate constant of activation (ka), rate constant of propagation (kp), and rate constant of β‐proton elimination (ktr) are not affected by the presence of impurities. To account for the retardation of polymerization in the presence of impurities, delay of proton transfer to monomer in the chain transfer step is proposed. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 3697–3704

“…The current method for the synthesis of PIBSI dispersants starts with the preparation of PIB with olefinic end groups through the acid‐catalyzed (AlCl 3 , BF 3 , and BF 3 complexes) polymerization of isobutylene (IB) . Development of new catalysts and catalyst complexes and more cost‐effective processes for the production of highly reactive (HR) PIB are currently active areas of research . Formation of PIB succinic anhydride (PIBSA) is accomplished by reaction of olefin‐terminated PIB with maleic anhydride (MAH), which occurs by either a chlorine‐mediated Diels–Alder reaction (traditional PIB derived from AlCl 3 catalyst) or a thermal ene reaction at temperatures greater than 200 °C (HR PIB derived from BF 3 catalyst) .…”

Section: Introductionmentioning

confidence: 99%

Synthesis of comb‐like dispersants and a study on the effect of dispersant architecture and carbon black dispersion

Holbrook

Masson

Storey

2019

Comb dispersants suitable for stabilization of carbonaceous deposits found in automotive lubricating oils were derived from the copolymerization of vinyl‐ether terminated polyisobutylene (VE‐PIB) macromonomers with maleic anhydride (MAH). The rate and degree of copolymerization of VE‐PIB with MAH was greatly influenced by the molecular weight of the VE‐PIB. Longer PIB tails imposed greater hindrance of the chain end resulting in slower propagation and lower degrees of copolymerization for PIB‐alt‐MAH copolymers. Functionalization of PIB‐alt‐MAH with a polyamine proceeded smoothly at elevated temperatures as evidenced by disappearance of anhydride stretches via Fourier transform infrared spectroscopy. Analogous linear and grafted dispersants were prepared to investigate the influence of architecture on the physical properties of the dispersants. Characterization of the intermediates and final dispersants was conducted by nuclear magnetic resonance, gel permeation chromatography, thermogravimetric analysis, and ultraviolet–visible. Using Langmuir adsorption studies and carbon black as a substitute for carbonaceous deposits, it was found that comb and grafted dispersants exhibit greater affinities for adsorption but decreased packing efficiencies in comparison to linear dispersants. Rheological studies investigating viscosity as a function of loading for dispersant/oil mixtures with carbon black present a similar finding. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1682–1696