High‐Molecular‐Weight Isobutene–Isoprene Copolymers Containing Unusually High Isoprene Content

Abstract

Summary: The 1:2 adduct of the highly electrophilic borane B(C6F5)3 with n‐decanoic (stearic) acid, [n‐C17H35CO2H][B(C6F5)3]2 exhibits sufficiently enhanced acidity that it is an excellent initiator for the carbocationic copolymerization of isobutene with isoprene in methylene chloride and methyl chloride. High conversions to gel free, high‐molecular‐weight copolymers containing up to 15 wt.‐% isoprene are readily obtained, consistent with the anion [n‐C17H35CO2{BC6F5)3}2]− being very weakly coordinating. Thus chain transfer following IP incorporation into the growing polymeric chain, which normally results in low average molecular weights, is much less of a factor here.The acidic 1:2 adduct of B(C6F5)3 with n‐decanoic acid, [n‐C17H35CO2H][B(C6F5)3]2, as an initiator for the carbocationic copolymerization of isobutene with isoprene.magnified imageThe acidic 1:2 adduct of B(C6F5)3 with n‐decanoic acid, [n‐C17H35CO2H][B(C6F5)3]2, as an initiator for the carbocationic copolymerization of isobutene with isoprene.

The Relationship between Specific Structure and Gas Permeability of Bromobutyl Rubber: A Combination of Experiments and Molecular Simulations

“…Besides, T g values of IIR and BIIR were estimate sketchy by using Sythia module in MS. Figure suggests that the increasing isoprene (or SABI) content in IIR (or BIIR) results in a rise of T g , which is in accordance with the work reported by McInenly . Moreover, it shows that the SABI unit exerted a more significant impact than the isoprene unit on T g .…”

“…It was reported that the low‐level unsaturated units between long polyisobutylene segments will bring about the excellent gas barrier and good flex properties of BIIR . However, only a few experimental studies on altering the copolymer composition of IIR rather than BIIR have been reported . For example, Garratt et al developed an initiating system for preparing IIR with high isoprene content and confirmed the high efficiency of the system .…”

“…For example, Garratt et al developed an initiating system for preparing IIR with high isoprene content and confirmed the high efficiency of the system . McInenly et al successfully prepared a high isoprene content IIR and found that the T g increased with increasing isoprene content . Despite these studies, large amounts of the synthesized polymer are still difficult to make due to the limited experimental conditions.…”

Complete devulcanization of sulfur‐cured butyl rubber by using supercritical carbon dioxide

“…As can be seen from Figure 7, the high frequency resonances at 1.108 ppm and 1.412 ppm were attributed to the methyl proton and methylene proton of the polyisobutylene units of butyl rubber 24, 30. Because of the low unsaturation, the weak frequency resonances in the region of 1.50–2.20 ppm were assigned to the isoprenyl units.…”

Synthesis and properties of bromide‐ functionalized poly(isobutylene‐co‐p‐ methylstyrene) random copolymer

“…Polyisobutylene (PIB) based materials are widely used commercially in a variety of products, such as automobile tires, sporting equipment, adhesive sealants, viscosity modifiers, chewing gums and drug eluting stents . The widespread use of these polymers can be attributed to their favorable properties, including exceptional thermal and chemical stability, impermeability to gas and water, high damping and high elasticity.…”