Synthesis and characterization of arborescent (hyperbranched) polyisobutylenes from the 4‐(1,2‐oxirane‐isopropyl)styrene inimer

Abstract

The synthesis of the novel inimer (initiator‐monomer) 4‐(1,2‐oxirane‐isopropyl)styrene EPOIM and the copolymerization of this inimer with isobutylene (IB) to form arborescent polyisobutylene (PIB) is described. Polymerizations were accomplished by use of TiCl4 coinitiator and the effect of reaction conditions was investigated. Size exclusion chromatography (SEC) was used demonstrate EPOIM incorporation across the whole molecular weight distribution. The average number of branch points (B) per chain measured by use of selective link destruction increased with increasing EPOIM/IB ratio and decreased with [TiCl4]. Large scale polymerizations were carried out based on results from small scale polymerizations. Architecture analysis carried out through use of branching parameters based on the radii of gyration Rg and hydrodynamic radii Rh measured by multidetector SEC corroborated the proposed arborescent architecture. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5847–5856, 2007

Monte Carlo Model for Arborescent Polyisobutylene Production in the Batch Reactor

“…Notice that molecules with 20 inimer units (corresponding to B kin = 19) have a noticeable influence on the MWD, even though the average branching level is B kin = 7.4. The current MC model is a significant advance over our previous PREDICI model because it will permit simulation of experimental data sets with measured values of B kin up to 32 …”

“…The estimates that we used for k p IIapp and k p SIapp are highly uncertain and the estimates used for k p MMapp , k p MIapp , k p IMapp , and k p SMapp (see Table ) are inaccurate because they were obtained by assuming that k p IIapp = k p SIapp = 0 and that no molecules with >15 IM units exist in the batch reactor. As a result, further parameter estimation studies are recommended so that reliable predictions of experimental data can be obtained, especially for arborescent IB production with high branching levels …”

“…Inimer homopolymerization simulations conducted using the model confirm that the molecular weight behavior is similar to that encountered during condensation polymerizations, with a slow initial rise in degree of polymerization, followed by a dramatic increase at long reaction times where conversion is high. Systematic parameter estimation will be required so that accurate simulation results can be obtained and model predictions can be tested using experimental data with high branching levels . Unfortunately, long computation times encountered using this MC model would make computation times for parameter estimation prohibitively long unless powerful computers are used.…”

“…The concept of “one‐pot” living homopolymerization of IM molecules was first introduced by Fréchet et al in 1995, which they named self‐condensing vinyl polymerization (SCVP) . Later, self‐condensing vinyl copolymerization (SCVCP) of inimers and vinyl monomers was performed experimentally …”

Hairy particle‐supported 4‐N,N‐dialkylaminopyridine: An efficient and recyclable nucleophilic organocatalyst

“…We prepared 1-(4-(2-(2-(4-vinylbenzyloxy)ethoxy)ethoxy)methyl)phenyl-1-(2 0 ,2 0 ,6 0 ,6 0 -tetramethyl-1 0 -piperidinyloxy)ethane, which is an inimer (initiator/monomer) 11 containing an NMRP initiator (Scheme 2). The inimer was then incorporated into the shell layer of coreshell crosslinked PS particles by a seeded emulsion polymerization (Scheme 1).…”