Polyisobutylene Research Articles

Chemical Stability Investigations of Polyisobutylene as New Binder for Application in Lithium Air-Batteries

ABSTRACT The side reactions of LiO 2 , Li 2 O 2 and Li 2 O, formed during the discharge process at the cathode/electrolyte interphase, are still a main challenge of lithium-air batteries. During these reactions, polyvinylidene difluoride (PVdF), as the commonly used cathode binder material, is decomposing, leading to a shorter lifetime of the battery. In this paper, we introduced and investigated polyisobutylene (PIB), a chemically and electrochemically inert polymeric material, to substitute PVdF as binder for lithium-air batteries. Results obtained by X-ray diffraction and spectroscopic methods showed, that PIB is far more stable in the presence of O 2 − , O 2 2− as well as O 2− species compared to PVdF. This distinct inertness makes PIB a promising binder for lithium-air batteries.

End-quenching of tert-chloride-terminated polyisobutylene with alkoxybenzenes: comparison of AlCl3 and TiCl4 catalysts

Functional polyisobutylenes were prepared by quenching living carbocationic PIB with alkoxybenzenes such as (3-bromopropoxy)benzene using AlCl3 or TiCl4 as catalyst.

Role of thermal, mechanical and oxidising treatment on structure and chemistry of carbon black and its impact on wear and friction: Part 2 – Boundary lubrication condition

Mineral oil formulations with zinc dialkyl dithiophosphate (ZDDP) and dispersant (poly isobutylene succinimide ashless dispersant or ‘PIBSA’) and fully formulated oils with and without carbon black were subjected to thermal and mechanical treatment and tribologically tested on TE 77 (high frequency reciprocating rig or ‘HFRR’) machine to examine the frictional performance during the test. These results were compared to oils without carbon black and oils with diesel soot. Results indicate that oils with just ZDDP and dispersant had the highest friction that remains constant for the duration of the test while oils with carbon black in the milled and oxidised condition had the lowest coefficient of friction and the smallest surface roughness in the tribofilm. The mechanism of wear with treated carbon black and diesel soot was found to be polishing wear as evidenced by the scanning probe microscopy images of the tribofilms. Tribofilms were analysed with X-ray absorption near edge structure (XANES) and it was seen that oils without carbon black or even with untreated carbon black had sulphates at the surface, while the oils with carbon black that were treated had a higher proportion of sulphides. A combination of both FeS and ZnS was found in the tribofilms along with short chain phosphates of Zn.

Rheology and adhesive properties of filled PIB-based pressure-sensitive adhesives. I. Rheology and shear resistance

Two nanosized fillers (fumed silica Rosil-175 up to 20 wt% and halloysite nanotubes up to 40 wt%) were used to suppress cold flow of polyisobutylene (PIB)-based adhesives. Rheological measurements revealed the presence of the yield stress in the PIB-halloysite system which is indicative of the three-dimensional network formation in the bulk of the matrix. However, further rheology tests identified low strength of the network. In case of Rosil, no yield stress was detected, only gradual increase in the viscosity. Shear bank testing showed 4–5 times increase in the PIB-halloysite system time to failure when 40 wt% of halloysite was incorporated into the PIB matrix. Increase in the time to failure for PIB-Rosil systems was over two orders of magnitude – at the Rosil content up to 20 wt%. Such superior properties of the Rosil adhesion joints are considered to be the result of Rosil high specific area and low strength of the halloysite nanotubes network.

Direct Chain End Functionalization of Living Polyisobutylene Using Phenoxyalkyl (Meth)acrylates.

Phenoxyalkyl acrylates and methacrylates were studied as quenching (capping) agents for living carbocationic polymerization of isobutylene (IB) at -70 °C in 40/60 (v/v) hexane/methyl chloride, catalyzed by TiCl4. Quenching reactions were carried out by reactivation by TiCl4 of preformed difunctional tert-chloride-terminated polyisobutylene (PIB) or by a one-step method in which IB polymerization and quenching were conducted sequentially in the same reactor. Chain-end concentrations ranged from 0.02 to 0.1 M, and quenchers were used at concentrations of 1.5-2.5 times the chain ends. The phenoxyalkyl (meth)acrylates were synthesized by reaction of (meth)acryloyl chloride with the corresponding phenoxyalkanol; alkylene tethers from two to eight carbons were examined. Quenched polymers were characterized by 1H and 13C NMR, MALDI-TOF mass spectrometry, and size exclusion chromatography (SEC). Alkylation was observed to occur exclusively at the para position of the phenoxy moiety, and SEC showed no coupling or molecular weight degradation as a result of quenching. For short tethers of two or three carbons, quenching was slow and incomplete due to competing loss of living chain ends presumably by carbocation rearrangement. For tethers of four, six, or eight carbons, quenching was much faster and yielded quantitative (meth)acrylate chain-end functionality (number-average functionality ≥1.98 by 1H NMR). MALDI-TOF-MS results were consistent with the expected end group structures. The carbonyl group of the quencher consumes one equivalent of Lewis acid in formation of a 1:1 complex; thus, the highest rate of quenching at a given Lewis acid concentration is achieved by using only a modest excess of quencher relative to living chain ends.

Thermoplastic elastomers of alloocimene and isobutylene triblock copolymers

A novel triblock copolymer, having a center block of high molecular weight polyisobutylene (PIB) and alloocimene (allo) end-blocks, was synthesized and the mechanical properties characterized. The phase-separated morphology consists of tethered PIB, with the glassy allo domains functioning as reinforcing filler. Thus, at ambient temperature the dynamic modulus is larger than that of PIB homopolymer by about 40%, and there is pronounced reinforcement from the glassy domains. The triblock polymer exhibits thermoplastic elastomer behavior, consistent with the structure. For temperatures above the allo glass transition (71 °C), the material undergoes an order–disorder transition, which causes substantial softening; however, this lability of the mechanical response is largely reversible. Since the repeat units of polyisobutylene cannot be crosslinked, this new material offers a route to processible, PIB based networks.

Synthesis of poly(poly(ethylene glycol) methacrylate)-polyisobutylene ABA block copolymers by the combination of quasiliving carbocationic and atom transfer radical polymerizations.

Systematic investigations are carried out on the synthesis of a series of new, unique ABA-type triblock copolymers consisting of the hydrophobic and chemically inert polyisobutylene (PIB) inner and the hydrophilic comb-shaped poly(poly(ethylene glycol) methacrylate) (PPEGMA) polymacromonomer as an outer block. Telechelic PIB macroinitiators with narrow molecular weight distributions (MWD) are synthesized by quasiliving carbocationic polymerization of isobutylene with a bifunctional initiator followed by quantitative chain end derivatizations. Atom transfer radical polymerization (ATRP) of PEGMAs with various molecular weights is investigated by using these macroinitiators. It is found that CuBr is an inefficient ATRP catalyst, while CuCl leads to high, nearly complete conversions of the PEGMA macromonomers. Gel permeation chromatography (GPC) analyses reveal slow initiation of PEGMA at relatively high PIB/PEGMA ratios or with PEGMAs of higher molecular weights due to steric hindrance between the macroinitiator and macromonomer. The occurrence of slow initiation, and not permanent termination, is proven by highly efficient ATRP of a low-molecular-weight monomer, methyl methacrylate, with the block copolymers as macroinitiators. Successful synthesis of PPEGMA-PIB-PPEGMA ABA block copolymers is obtained by using either low-molecular-weight PEGMA or relatively low macroinitiator/macromonomer ratios. Differential scanning calorimetry (DSC) indicates phase separation and significant suppression of the crystallinity of the pendant poly(ethylene glycol) (PEG) chains in these new block copolymers.

The Mitigation Effect of Synthetic Polymers on Initiation Reactivity of CL-20: Physical Models and Chemical Pathways of Thermolysis

In this paper, the thermal decomposition physical models of different CL-20 polymorph crystals and their polymer bonded explosives (PBXs) bonded by polymeric matrices using polyisobutylene (PIB), acrylonitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), Viton A, and Fluorel binders are obtained and used to predict the temperature profiles of constant rate decomposition. The physical models are further supported by the detailed decomposition pathways simulated by a reactive molecular dynamics (ReaxFF-lg) code. It has been shown that both e-CL-20 and α-CL-20 decompose in the form of γ-CL-20, resulting in close activation energy (169 kJ mol–1) and physical model (first-order autoaccelerated model, AC1). Fluoropolymers could change the decomposition mechanism of e-CL-20 from the “first-order autocatalytic” model to a “three-dimensional nucleation and growth” model (A3), while the polymer matrices of Formex P1, Semtex, and C4 could change e-CL-20 decomposition from a single-step process to a multis...

Detecting the Rouse and Sub-Rouse Modes in Poly(Butyl Acrylate) and Poly(Ethyl Acrylate) Through Two-Dimensional Dynamic Mechanical Spectra

The difficulties of observing sub-Rouse modes (SRM) and Rouse modes (RM) in acrylate polymers has resulted in many arguments and disputes concerning the nature of their glass-rubber transition. Because different modes have different sensitivity to external perturbations, the two-dimensional dynamic analysis mechanical spectra (2D-DMS) was introduced to detect the local segments motion (LSM), SRM, and RM in poly(butyl acrylate) (PBA) and poly(ethyl acrylate) (PEA). The results of the asynchronous spectra showed the LSM, SRM, and RM of PBA and PEA are located, respectively, at about (−46 ∼ −29°C), (−28 ∼ −10°C), (−4 ∼ 27°C), and about (−12 ∼ −5°C), (−3 ∼ 6°C), and (10 ∼ 44°C). Furthermore, the LSM and SRM of PBA and PEA have an overlap in the synchronous spectra. This is suggested to be caused by the higher coupling effect in PBA and PEA when compared with strong glass formation polymers, like polyisobutylene (PIB).

Synthesis and properties of arborescent polyisobutylene‐poly(ethylene oxide) graft copolymers: a comparison of linear and arborescent graft copolymer architectures

AbstractPolymer architecture can have a significant effect on the properties and potential applications of materials. In this study, arborescent polyisobutylene (PIB)‐poly(ethylene oxide) (PEO) graft copolymers with varying PEO content were synthesized from arborescent PIB‐co‐polyisoprene and compared with linear PIB‐PEO graft copolymers. By AFM imaging, phase separation was detected in a 48 wt% PEO arborescent copolymer. Tensile testing revealed that, in general, increasing PEO content led to increased tensile strength and Young's modulus but decreased elongation at break. Arborescent analogues exhibited lower elongation at break and lower strength compared with linear analogues but also less plastic deformation and yielding behaviour. Like linear analogues of comparable PEO content, films of the arborescent graft copolymers resisted the adsorption of rhodamine‐labelled fibrinogen, suggesting that they may also exhibit non‐fouling properties. Finally, the assembly of these amphiphilic copolymers in aqueous solution was investigated. Unlike the linear analogues, the sizes of the assemblies were not greatly affected by their method of preparation. This work demonstrates that it is possible to prepare PIB‐based materials with a wide range of interesting properties by tuning not only the content of PEO but also the architectures of the macromolecules. © 2014 Society of Chemical Industry

The Application of Heavy Alkyl Benzene in Engine Oil and Hydraulic Fluid Formulations

Heavy alkyl benzene (HAB) is a byproduct in the process of linear alkyl benzene (LAB) production. It is used as heat transfer oil and lubricating greases. In this article the potential of the usage of HAB in the formulation of gasoline and diesel engine oils as well as hydraulic fluid is indicated. With the aim of passing 5W30, 5W40, 10W40, and 15W40 standards, different engine oils have been formulated. The formulations contain various amounts of HAB as minor component, and miscellaneous quantities of solvent neutral 100 (SN-100), SN-150, and SN-650 as major component. The measurement of typical properties of obtained oils indicates that some of them do have the intended criteria. Test field of the recent oils designate that they have good performance. In the next step, different blends of HAB as major component and polyisobutene (PIB) as minor component have successfully been employed in the formulation of several ISO grade hydraulic fluids. The achieved materials do have suitable air release and demulsibility.

A mid-infrared sensor for the determination of perfluorocarbon-based compounds in aquatic systems for geosequestration purposes

Perfluorocarbon (PFC) compounds have been used as chemical tracer molecules to understand the movement of supercritical carbon dioxide for geosequestration monitoring and verification purposes. A commonly used method for detecting PFCs involves the collection of a sample from either soil-gas or the atmosphere via carbon-based sorbents which are then analyzed in a laboratory. However, PFC analysis in aquatic environments is neglected and this is an issue that needs to be considered since the PFC is likely to undergo permeation through the overlying water formations. This paper presents for the first time an innovative analytical method for the trace level in situ detection of PFCs in water. It reports on the development of a sensor based on mid-infrared attenuated total reflection (MIR-ATR) spectroscopy for determining the concentration of perfluoromethylcyclohexane (PMCH) and perfluoro-1,3-dimethylcyclohexane (PDCH) in aquatic systems. The sensor comprises a zinc selenide waveguide with the surface modified by a thin polymer film. The sensitivity of this device was investigated as a function of polymer type, coating thickness, and solution flow rates. The limit of detection (LOD) was determined to be 23ppb and 79ppb for PMCH and PDCH, respectively when using a 5μm thick polyisobutylene (PIB) coated waveguide. This study has shown that the MIR-ATR sensor can be used to directly quantify PFC-based chemical tracer compounds in water over the 20–400ppb concentration range.

Synthesis of amphiphilic ABA triblock copolymer bearing PIB and perfluorocyclobutyl aryl ether-containing segments via sequential living carbocationic polymerization and ATRP

A series of amphiphilic ABA triblock copolymers containing polyisobutylene (PIB) and poly(p-(2-(4-biphenyl)perfluorocyclobutoxy)phenyl methacrylate) (PBPFCBPMA) segments was synthesized via sequential living carbocationic polymerization and atom transfer radical polymerization (ATRP). Living carbocationic polymerization of isobutylene was initially performed at -78 degrees C in n-hexane-CH3Cl followed by end-capping with 1,3-butadiene to provide a well-defined diallyl-Cl-terminated PIB with a narrow molecular weight distribution (M-w/M-n = 1.26). The PIB functionalized at both ends was further transformed into Br-PIB-Br, an ATRP macroinitiator bearing one ATRP initiating group at each end. The target triblock copolymers of PBPFCBPMA-b-PIB-b-PBPFCBPMA with a relatively narrow molecular weight distribution (M-w/M-n <= 1.42) were obtained via ATRP of BPFCBPMA at 70 degrees C in tetrahydrofuran initiated by Br-PIB-Br. The self-assembly behavior of these triblock copolymers in n-hexane, acetone, and 1,1,1-trifluoroacetone was investigated by transmission electron microscopy. It was found that large spherical compound micelles with PIB blocks as coronas were formed in n-hexane, whereas large compound micelles with fluorine-containing PBPFCBPMA blocks as coronas were formed in acetone and 1,1,1-trifluoroacetone.

Using Polyisobutylene as a Non-Fluorinated Binder for Coated Lithium Powder (CLiP) Electrodes

Binder formulations based on N-methylpyrrolidone/polyvinylidene fluoride (NMP/PVdF) or water/carboxymethyl cellulose (H2O/CMC) are state of the art in the fabrication of anodes for lithium-ion battery (LIB) applications. However, in combination with metallic lithium these materials tend to degrade. Therefore, for the production and operation of anodes employing metallic lithium particles another binder system, which is flexible, chemically and electrochemically inert, inexpensive, commercially available and, especially for industrial applications, usable within a broad temperature range, is needed. Polyisobutylene (PIB) is able to fulfil these criteria. The advantages of this binder are its inert structure and its solubility in alkanes (e.g. heptane), which are inert against lithium metal, as well. In this work we will introduce heptane/PIB as a binder formulation for the preparation of electrodes from coated lithium powder (CLiP) particles. We demonstrate that CLiP electrodes fabricated with this binder system exhibit better electrochemical performance than electrodes made with NMP/PVdF or tetrahydrofuran (THF)/PVdF formulations. Furthermore, CLiP immersed in heptane/PIB show also better thermal stability compared to CLiP immersed in NMP/PVdF and THF/PVdF.

Investigation of pseudo lateral field excited acoustic wave gas sensors with finite element method

To improve the weak piezoelectric excitation of lateral field excited (LFE) acoustic wave sensors in air, a novel bulk acoustic wave device, named pseudo LFE acoustic wave sensor, is proposed in this paper. The commercially available finite element software, COMSOL Multiphysics, is adopted to analyze pseudo LFE acoustic wave gas sensors and further calculate their sensitivities to electric conductivity variation of the polyisobutylene (PIB) sensing film. An AT-cut quartz plate with a thickness of 185 µm is chosen as the piezoelectric substrate due to its tiny temperature coefficient to frequency for thickness shear mode (TSM). After the mesh convergence analysis, a mesh level is decided for following calculations. In frequency response analysis, a bare pseudo LFE sensor shows a pure TSM and a stronger excitation than a bare LFE sensor. The experiments also verify this result. In sensitivity analysis, a gradual conductivity increase of the sensing film from 0 to 3 S/m causes a significant resonance frequency decrease of the pseudo LFE sensor. Besides, the pseudo LFE sensor exhibits an excellent sensitivity to the film conductivity variation, about 30 times as high as the QCM sensor. Finally, the electrode dimensions of pseudo LFE sensors are discussed for optimizing device performances. One can find ringed floating electrodes exhibit greater sensitivity than circular ones. Moreover, a larger gap width between the LFE electrodes also contributes to larger sensitivity but weakens piezoelectric excitation. The results conclude that the pseudo LFE sensor exhibits a satisfactorily large admittance and an excellent sensitivity to external electrical fluctuation.

Using Soluble Polymers to Enforce Catalyst‐Phase‐Selective Solubility and as Antileaching Agents to Facilitate Homogeneous Catalysis

AbstractThe enforced phase‐selective solubility of polyisobutylene (PIB)‐bound RhII catalysts in biphasic heptane/acetonitrile mixtures can be used not only to recycle these catalysts but also to minimize bimolecular reactions with ethyl diazoacetate. When cyclopropanation and OH insertion reactions are carried out with PIB‐bound RhII catalysts either with or without addition of an unfunctionalized hydrocarbon polymer cosolvent, dimer by‐product formation is suppressed even without slow syringe pump addition of the ethyl diazoacetate. This suppression of by‐product formation is shown to be due to increased phase segregation of the soluble polymer‐bound catalyst and the ethyl diazoacetate reactant. These studies also reveal that added hydrocarbon polymer cosolvents can function as antileaching agents, decreasing the already small amount of a soluble polymer‐bound species that leaches into a polar phase in a biphasic mixture during a liquid/liquid separation step.

Using soluble polymers to enforce catalyst-phase-selective solubility and as antileaching agents to facilitate homogeneous catalysis.

The enforced phase-selective solubility of polyisobutylene (PIB)-bound Rh(II) catalysts in biphasic heptane/acetonitrile mixtures can be used not only to recycle these catalysts but also to minimize bimolecular reactions with ethyl diazoacetate. When cyclopropanation and O-H insertion reactions are carried out with PIB-bound Rh(II) catalysts either with or without addition of an unfunctionalized hydrocarbon polymer cosolvent, dimer by-product formation is suppressed even without slow syringe pump addition of the ethyl diazoacetate. This suppression of by-product formation is shown to be due to increased phase segregation of the soluble polymer-bound catalyst and the ethyl diazoacetate reactant. These studies also reveal that added hydrocarbon polymer cosolvents can function as antileaching agents, decreasing the already small amount of a soluble polymer-bound species that leaches into a polar phase in a biphasic mixture during a liquid/liquid separation step.

Synthesis of functionalized polyisobutylenes using the propylene epoxide/TiCl4initiating system

In this paper, we report the synthesis of symmetric and asymmetric telechelic polyisobutylenes (PIBs). A PIB with a primary hydroxy head group and an allyl end group (HO–PIB–Allyl, Mn = 4300 g mol−1; Mw/Mn = 1.2) was synthesized by living carbocationic polymerization of isobutylene (IB) using propylene epoxide as an initiator and allyltrimethylsilane as a terminating agent. Thiol–ene click chemistry using 2-mercaptoethanol and 1,2-ethanedithiol yielded an asymmetric HO–PIB–SEt–OH (Mn = 4646 g mol−1; Mw/Mn = 1.18) and a symmetric HO–PIB–OH (Mn = 8594 g mol−1; Mw/Mn = 1.2) respectively. A symmetric allyl telechelic PIB (Mn = 8669 g mol−1; Mw/Mn = 1.2) was prepared by enzymatic transesterification of divinyl adipate with the primary hydroxy group of HO–PIB–Allyl.

Lubrication Behavior of Binary Blends of Solvent Neutral-150: Polyalpholefin-100 and Solvent Neutral-150: Polyisobutene

Different blends containing 5%, 10%, 15%, 20%, 25%, and 30% of polyalphaolefin-100 (PAO-100) as a minor component and solvent neutral-150 (SN-150) as a major component were prepared. The important lubrication properties of the blends were then measured. The obtained results indicate that upon increasing the weight percentage of PAO-100, the viscosity index (VI) rises, the cold cranking simulator (CCS) diminishes, and viscosities approach the corresponding values due to solvent neutral-500 (SN-500). Different equations were derived between the viscosity and VI and weight percentage of PAO-100. A similar procedure was employed for blends containing 1%, 5%, 10%, 12%, and 15% of polyisobutene (PIB). In this case, results parallel to PAO-100 were obtained. The 30% PAO-100: SN-150 and 12% PIB: SN-150 mixtures were successfully employed for the equalization of semisynthetic engine oil SAE 20W50 API SJ from Millers Company. Biodegradability as well as tribotests were performed on the recent blends and compared with corresponding values due to SN-150.

Field-Controlled Ion Doping of Graphene

Doping technologies are needed for the development of tunnel field-effect transistors based on graphene and other single-layer two-dimensional materials. Here we utilize Li+ and ClO4 − ions in polyethylene oxide (PEO) to enable dynamic and reconfigurable doping of graphene under electric field control. Ions are drifted across the PEO to the graphene where they induce electron or hole conductivity. Use of PEO:LiClO4 for ion-doping of carbon nanotubes [1], graphene [2, 3] and MoS2[4] have all incorporated the ion conductor and field plate above the transistor channel. This requires a dry process because the developers used in photolithography attack and contaminate PEO. This further restricts the field plate formation process to shadow evaporation or to macroscopic contacts formed by probes. Here we report on a new dry transfer process which allows the transistor to be placed on top of the PEO and the doping to be field-controlled by the substrate back gate. In this paper we show the transfer process and characteristics of the ion motion and conductivity modulation under field-control. The dry transfer process is illustrated in Fig. 1. To create the top portion of the device, source and drain contacts are patterned onto wide area graphene formed by chemical vapor deposition. Polyisobutylene (PIB) and a PDMS stamp are then applied as handling layers (Fig. 1b). The Cu substrate is then etched in ammonium persulfate (APS) and the top portion is joined to the bottom (Fig. 1e). We have fabricated devices with both Au and graphene backgates, and initial tests were performed with an Au backgate, patterned into stripes to minimize leakage current through the electrolyte (Fig. 2). Doping in the graphene channel is controlled by the backgate voltage (Vbg ). The conductivity, monitored by the drain current, (Id ), is varied by a factor of four by sweeping Vbg at 0.5 V/s from −10 to 10 V (Fig. 3). The shift of the current minima (Dirac points) from zero are a direct measure of the ion doping of the graphene channel.To characterize the retention of electrostatic doping, a 5 V backgate pulse is applied for 1 second and removed for 10 seconds while monitoring the drain current (Fig. 4). The current decreases by ~10% as the ions are polarized and then released. Acknowledgements: This work was supported in part by the Center for Low Energy Systems Technology (LEAST), one of the six SRC STARnet Centers, sponsored by MARCO and DARPA.[1] C. Lu et al. Nano Lett. 4, pp. 623–627 (2004)[2] A. Das et al., Nat. Nanotech, 3, pp. 201-215 (2008)[3] D. Efetov and P. Kim, Phys. Rev. Lett., 105, pp. 256805 (2010)[4] M. Lin, et al., J. Phys. D, 45, 345102 (2012).