Living cationic polymerization of isobutylene (IB) with 1-chlorine-2,4,4-trimethyl pentane (TMPCl)/TiCl₄/isopropanol (iPrOH) or isoamylol (iAmOH) has been achieved in the presence of 2,6-di-tert-butylpyridine (DtBP) at −80°C. Polyisobutylenes with nearly theoretical M_n based on TMPCl molecules and more than 90% of tert-chlorine-end groups could be obtained at high [TMPCl]. The β-proton elimination from CH₃ in growing chain ends increased with increasing polymerization temperature and decreasing solvent polarity. A chain-transfer-dominated cationic polymerization process with H₂O/TiCl₄/iAmOH could be achieved in n-hexane at −30°C. The monomer conversion and content of exo-olefin end groups increased while molecular weight decreased with increasing [iAmOH]. To the best of our knowledge, this is the first example to achieve the direct synthesis of highly reactive polyisobutylene with low M_n of 1200∼1600, carrying more than 80% of exo-olefin terminals by a single-step process via cationic polymerization co-initiated by TiCl₄ in nonpolar hydrocarbon. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42232.

The suspension cationic polymerization of isobutyl vinyl ether (IBVE) in aqueous medium could be achieved by using H₃PW₁₂O₄₀, AlPW₁₂O₄₀, FePW₁₂O₄₀, K₃PW₁₂O₄₀, or Na₃PW₁₂O₄₀ as efficient water-tolerant coinitiators in the presence of HCl. The addition reaction of IBVE with H₂O occurred to form IBVE–H₂O adduct and then subsequent decomposition immediately took place or turned to acetaldehyde diisobutyl acetal (A) in the presence of AlPW₁₂O₄₀, and (A) decomposed rapidly to form 2-isobutanol (B) and acetaldehyde (C). Cationic polymerization of IBVE in aqueous medium was promoted greatly with increasing HCl concentration and proceeded extremely rapidly to get high polymer yield even at low concentration of AlPW₁₂O₄₀ of 0.3 mM. A sufficient amount of HCl was needed to decrease the hydrolysis of initiator IBVE–HCl and to accelerate the polymerization in aqueous medium simultaneously. The yield and molecular weight of poly(IBVE) increased with increasing concentrations of HCl and AlPW₁₂O₄₀ or with decreasing temperature. The isotactic-rich poly(IBVE)s with m diad of around 60%, having M_n of 1200–4500 g mol⁻¹ and monomodal molecular weight distribution could be obtained via cationic polymerization of IBVE in aqueous medium. This is the first example of cationic polymerization of IBVE in aqueous medium coinitiated by heteropolyacid and its salts. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

Cationic polymerizations of isobutylene (IB) with H₂O/FeCl₃/isopropanol (iPrOH) initiating system were conducted in nonpolar hydrocarbon media, such as n-hexane or mixed C₄ fractions at −40 to 20 °C. This cationic polymerization is a chain-transfer dominated process via highly selective β-proton elimination from CH₃ in the growing chain ends, leading to formation of highly reactive polyisobutylenes (HRPIBs) with large contents (> 90 mol %) of exo-olefin end groups (structure A). The content of structure A remained nearly constant at about 97 mol % during polymerization and isomerization via carbenium ion rearrangement could be suppressed in nonpolar media. First-order kinetics with respect to monomer concentration was measured for selective cationic polymerization of IB in the mixed C₄ fraction feed at −30 °C and the apparent rate constant for propagation was 0.028 min⁻¹. High polymerization temperature (T_p) or [FeCl₃] accelerate β-proton elimination or isomerizations and simultaneously decrease selectivity of β-proton abstraction from CH₃. Molecular weight decreased and molecular weight distribution (MWD) became narrow with increasing T_p or [FeCl₃]. To the best of our knowledge, this is the first example to achieve high quality HRPIBs with near 100% of exo-olefin terminals and relatively narrow MWD (M_w/M_n = 1.8) by a single-step process in nonpolar hydrocarbon media. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4200–4212

Highly reactive polyisobutylenes (HRPIBs) with very large proportion (up to 95 mol%) of exo-double bond end groups and number average molecular weight (M_n) of 5400–8500 Dalton (Da) could be successfully synthesized by the selective cationic polymerization of isobutylene (IB) from the mixed C₄ fraction feed using o-cresol/AlCl₃ as initiating system at −20°C. A possible mechanism was proposed for the cationic polymerization process. The presence of large weakly coordinating counteranion in propagating species could lead to decreasing the possibility of the side transfer reactions via carbenium ion arrangements. This o-cresol/AlCl₃ initiating system exhibited extremely high selectivity toward IB polymerization in the mixed C₄ fraction feed and a good property for rapid β-proton abstraction from CH₃ in the growing polyisobutylenes (PIBs) chain ends. High extent of α-double bond end groups in HRPIBs prepared in the mixed C₄ fraction feed could be comparable to that in those commercially produced by cationic polymerization of IB in inert solvent (e.g. hexane). To our knowledge, this is the first example to achieve HRPIBs via completely selective polymerization of IB from C₄ mixed feed with AlCl₃-based initiating system, providing a potentially practical process for its simplicity and low costs. Copyright © 2011 John Wiley & Sons, Ltd.

A simple but effective FeCl₃-based initiating system has been developed to achieve living cationic polymerization of isobutylene (IB) using di(2-chloro-2-propyl) benzene (DCC) or 1-chlorine-2,4,4-trimethylpentane (TMPCl) as initiators in the presence of isopropanol (iPrOH) at −80 °C for the first time. The polymerization with near 100% of initiation efficiency proceeded rapidly and completed quantitatively within 10 min. Polyisobutylenes (PIBs) with designed number-average molecular weights (M_n) from 3500 to 21,000 g mol⁻¹, narrow molecular weight distributions (MWD, M_w/M_n ≤ 1.2) and near 100% of tert-Cl terminal groups could be obtained at appropriate concentrations of iPrOH. Livingness of cationic polymerization of IB was further confirmed by all monomer in technique and incremental monomer addition technique. The kinetic investigation on living cationic polymerization was conducted by real-time attenuated total reflectance Fourier transform infrared spectroscopy. The apparent constant of rate for propagation (k_p^A) increased with increasing polymerization temperature and the apparent activation energy (ΔE_a) for propagation was determined to be 14.4 kJ mol⁻¹. Furthermore, the triblock copolymers of PS-b-PIB-b-PS with different chain length of polystyrene (PS) segments could be successfully synthesized via living cationic polymerization with DCC/FeCl₃/iPrOH initiating system by sequential monomer addition of IB and styrene at −80 °C. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Summary: GPPS/cis-SB blends with high performance were prepared by adding 3–5 wt.-% stereoregular butadiene-styrene block copolymers (cis-SB) with a high cis-1,4 configuration of around 97% into general purpose polystyrene (GPPS). The micromorphology of the GPPS/cis-SB blends was characterized by transmission electron microscopy (TEM). Mechanical properties including tensile and impact properties were studied and the fracture surfaces of tensile and impact test specimens were characterized by scanning electron microscopy (SEM). PB domains of 10–30 nm with a blurry interface were tethered by continuous PS domains. The fracture surface of the tensile test piece of GPPS was relatively smooth while the fractography of patch patterns separated by river patterns was formed when the tensile specimens of GPPS/cis-SB blends were broken, which may be due to the nanometer-scale rubber phases with high cis-1,4 configuration and some partially crystalline PS segments in the cis-SB block copolymer. It is found that GPPS could be greatly toughened by introduction of a small amount of cis-SB and the tensile strength and elongation at break could also be increased.

The controlled cationic polymerization of isobutylene (IB) initiated by H₂O as initiator and TiCl₄ as coinitiator was carried out in n-Hexane/CH₂Cl₂ (60/40, v/v) mixture at −40 °C in the presence of N,N-dimethylacetamide (DMA). Polyisobutylene (PIB) with nearly theoretical molecular weight (M_n = 1.0 × 10⁴ g/mol), polydispersity (M_w/M_n) of 1.5 and high content (87.3%) of reactive end groups (tert-Chlorine and α-double bond) was obtained. The Friedel-Crafts alkylation of triphenylamine (TPA) with the above reactive PIB was further conducted at different reactions, such as [TPA]/[PIB], solvent polarity, alkylation temperature, and time. The resultant PIBs with arylamino terminal group were characterized by ¹H NMR, UV, and GPC with RI/UV dual detectors. The experimental results indicate that alkylation efficiency (A_eff) increased with increases in [TPA]/[PIB], reaction temperature, and reaction time and with a decrease in solvent polarity. The alkylation efficiency could reach 81.0% at 60/40(v/v) mixture of n-Hex/CH₂Cl₂ with [TPA]/[PIB] of 4.49 at 50 °C for 54 h. Interestingly, the synthesis of PIB with arylamino terminal group could also be achieved in one pot by combination of the cationic polymerization of IB initiated by H₂O/TiCl₄/DMA system with the successive alkylation by further introduction of TPA. Mono-, di- or tri-alkylation occurred experimentally with different molar ratio of [TPA]/[PIB]. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 936–946, 2008