Endfunctional polymers possess significant industrial and scientific importance. Sulfonyl endgroups, such as tosyl and nosyl endfunctionalities, due their ease of substitution are highly desired for ...a variety of polymer structures. The sulfonylation of hydroxyl-terminated polyisobutylene (PIB-OH), a chemically and thermally stable, biocompatible, fully saturated polymer, with tosyl chloride (TsCl) and nosyl chloride (NsCl) is presented in this study. PIB-OHs derived from commercial exo-olefin-ended PIB (PIB
-OH) and allyl-terminated polymer made via quasiliving carbocationic polymerization of isobutylene (PIB
-OH) were tosylated and nosylated in the presence of 4-dimethylaminopyridine (DMAP), pyridine and 1-methylimidazole (1-MI) catalysts and triethylamine (TEA). Our systematic investigations revealed that the end product distribution strongly depends on the relative amount of the components, especially that of TEA. While PIB
-OTs with quantitative endfunctionality is readily formed from PIB
-OH, its nosylation is not as straightforward. During sulfonylation of PIB
-OH, the formed tosyl and nosyl endgroups are easily substituted with chloride ions, formed in the first step of sulfonylation, leading to chloride termini. We found that decreased amounts of TEA afford the synthesis of PIB
-OTs and PIB
-ONs with higher than 90% endfunctionalities. These sulfonyl-ended PIBs open new ways for utilizing PIB in various fields and in the synthesis of novel PIB-containing macromolecular architectures.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Under optimized synthesis conditions, for the first time, polyisobutylene‐based polyurethane (PIB–PU) is prepared with 70% PIB soft segment (i.e., a bioinert and calcification‐resistant PU) with Mn > ...100 000 Da, 32 MPa ultimate strength, and 630% elongation. The key parameters for this achievement are a) the precise stoichiometry of the polyurethane forming reaction, specifically the use of highly purified di‐isocyanate (4,4′‐methylene‐bis (phenyl isocyanate), MDI), and b) the increased solid content of the synthesis solution to the limit beyond which increased viscosity prevents stirring. The shape of the stress–strain trace of PIB–PU indicates a two‐step failure starting with a reversible elastic (Hookean) region up to ≈50% yield, followed by a slower linearly increasing high‐modulus‐deformation region suggesting the strengthening of PIB soft segments by entanglement/catenation, and the hard segments by progressively ordering urethane domains. This PIB–PU is a candidate for a fully synthetic bioprosthetic heart valve since preliminary studies show that PIB–PU has impressive fatigue life.
The improved synthesis of polyisobutylene‐based polyurethane (PIB–PU) containing 70 wt% PIB leads to superior thermoplastic elastomers for the preparation of a fully synthetic bioprosthetic heart valve and other impantable medical devices.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Calcification of implanted biomaterials is highly undesirable and limits clinical applicability. Experiments were carried out to assess the calcification resistance of polyisobutylene (PIB), ...PIB‐based polyurethane (PIB‐PU), PIB‐PU reinforced with (CH3)3N+CH2CH2CH2NH2 I−‐modified montmorillonite (PIB‐PU/nc), PIB‐based polyurethane urea (PIB‐PUU), PIB‐PU containing S atoms (PIBS‐PU), PIBS‐PU reinforced with (CH3)3N+CH2CH2CH2NH2 I−‐modified montmorillonite (PIBS‐PU/nc), and poly(isobutylene‐b‐styrene‐b‐isobutylene) (SIBS), relative to that of a clinically widely implanted polydimethylsiloxane (PDMS)–based PU, Elast‐Eon (the “control”). Samples were incubated in simulated body fluid for 28 days at 37°C, and the extent of surface calcification was analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), energy‐dispersive X‐ray spectroscopy (EDX), X‐ray photoelectron spectroscopy (XPS), and Fourier‐transform‐infrared (FT‐IR) spectroscopy. Whereas the PDMS‐based PU showed extensive calcification, PIB and PIB‐PU containing 72.5% PIB, ie, a polyurethane whose surface is covered with PIB, were free of calcification. PIBS‐PU and PIB‐PUU, ie, polyurethanes that contain S or urea groups, respectively, were slightly calcified. The amine‐modified montmorillonite‐reinforcing agent reduced the extent of calcification. SIBS was found slightly calcified. Evidently, PIB and materials fully coated with PIB are calcification resistant.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Although perovskite solar cells (PSC's) have produced remarkable energy conversion efficiencies, their underperforming durability is the key challenge for the technology to be commercially viable. In ...this work, for the first time, we use gas chromatography - mass spectrometry (GC-MS) to reveal signature volatile products of the decomposition of organic hybrid perovskites under thermal stress. In addition, we are able to use GC-MS to confirm that a low-cost polymer/glass stack pressure-tight encapsulation is effective in supressing such outgassing. Using such encapsulation scheme, CH
NH
(MA) containing multi-cation multi-halide perovskite solar cells survived more than 1800 hours of Damp Heat test and 75 cycles of Humidity Freeze test exceeding the requirement of IEC61215:2016 standard for the first time.
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Block copolymers of polyisobutylene (PIB) with side-chain fatty acid-containing polymethacrylate segment with varying n-alkyl side-chains were synthesized by the combination of living ...cationic and reversible addition-fragmentation chain transfer (RAFT) polymerizations. Hydroxyl-terminated PIB (PIB-OH) was converted into macro-chain transfer agent (PIB-CDP macro-CTA) and used during the RAFT polymerization of fatty ester methacrylate (FEMA) monomers to obtain the block copolymers. Block copolymers were characterized by 1H NMR spectroscopy, size exclusion chromatography (SEC), and thermogravimetric analysis (TGA). The block copolymers showed varied crystalline behaviour depending on the chain length of the fatty acids in the polymethacrylate segment, confirmed by differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS), wide-angle X-ray scattering (WAXS), polarized optical microscopy (POM), and transmission electron microscopy (TEM). SAXS and POM analysis above the crystalline melting temperature (Tm) of the block copolymers showed crystalline to amorphous phase transformation, which upon cooling below their Tm regenerated crystalline morphology (lamella-like structure). Density functional theory (DFT) calculations were performed to support interlamellar distances determined from the SAXS study. Overall the modification in the orderliness of the lamellar orientation due to the amorphous PIB segment within the fatty acid-containing block copolymer leads to a new direction toward materials with modified physical properties.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This publication concerns the synthesis of a novel class of hybrid thermoset/thermoplastic elastomers, i.e., double cross‐linked polyisobutylene‐based polyurethanes (xPIB‐PUs), together with their ...processing and some key properties. These materials are designed to exhibit a combination of properties for indwelling medical applications, specifically for heart valve prostheses. The chemical cross‐links are introduced by well‐defined 3‐arm PIB stars fitted with HO‐end groups of molecular weights (MWs) of Mn = 3081 and 9000 g mole−1 and narrow MW dispersities (<1.3). Processibility of xPIB‐PU containing 70 wt% PIB (for biocompatibility and calcification resistance) is achieved by driving the syntheses to high conversions (>97%) close to but still below the gel point and completing the cross‐linking in heated molds. The processibility period (minutes) is controlled by controlling the MW of the cross‐linking agent in the 3081 to 9000 g mole−1 range. Blends of 3‐arm stars and linear bifunctional PIBs can also control the processibility period. The creep resistance of xPIB‐PU is significantly improved (from 13.2% to 5.5%) relative to physically cross‐linked PIB‐PU. xPIB‐PUs exhibit negligible permanent set (1–2%), and high Young's modulus (41 MPa). The stress/strain properties of xPIB‐PUs are also investigated. The data clearly show the contribution of two modes of cross‐linking.
This work discloses a novel class of precision synthetized polymers, double cross‐linked polyisobutylene‐based polyurethanes (xPIB‐PU), together with the conditions for their processing, and key properties. xPIB‐PU of 30/70 wt% hard/soft phase is a promising indwelling medical material, specifically, for heart valve prosthesis. The figure helps visualizing the micromorphology of xPIB‐PU.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Naphthene transformer oil (NTO), poly-dimethyl-siloxane (PDMS), and polyisobutylene (PIB) are the most regularly used insulating oils in the power industry, but the comparative investigation on their ...degradation mechanism has not been carried out yet. Based on ReaxFF simulation, this work presents a microscopic examination of the cracking mechanisms of NTO, PDMS, and PIB. In setting up the study system, the elements influencing the cracking of insulating oil, such as time length, temperature, and moisture content, were set up as a single variable to be studied and assessed on a case-by-case basis. In addition, a macroscale comparison study is done in conjunction with a thermal aging experiment, and the simulation data are in good agreement with the experimental data. The creation of the characteristic gas accelerates as temperature rises, intensifying the breaking of all three insulating oils. Furthermore, it is discovered that temperature fluctuation has the biggest influence on the amount of the gas content in PIB. Based on the results, it is possible to further investigate the fault diagnosis criteria in order to ensure the safety of electrical equipment.
In this study, Alkenyl succinimides with different alkyl chain lengths were synthesized using polyisobutylene (PIB) with the molecular weights of 1000 and 1300, which displayed the best functional ...properties. The secondary amines found in b-Polyisobutylene succinimide (b-PIBSI) dispersants were prepared by attaching PIB chains to a polyamine core via two succinimide moieties. In this work, detergent/dispersant type additives were synthesized based on polyisobutylene succinic anhydride (PIBSA) and its aminated compounds (PIBSI) with tetraethylenepentamine (TEPA). The resulting PIBSA and PIBSI characterized by Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (
1
H-NMR), and gel permeation chromatography (GPC) spectroscopies were greatly complicated because of the interactions between the carbonyls of the succinimide groups and unreacted secondary amines of the Mb-PIBSI dispersants. The viscoelasticity of obtained PIBSI indicated the increase in storage modulus with time which illustrated the increase in the solid-like properties of PIBSI. Therefore, an alternative procedure was developed based on fluorescence quenching of the succinimides by secondary amines and urethane groups.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
A cost‐effective strategy has been developed for the synthesis of polystyrene‐polyisobutylene‐polystyrene (PS‐PIB‐PS) triblock copolymer (SIBS) with relative narrow molecular weight distribution ...(MWD) via the addition of Ti(OiPr)4. First, the controlled polymerization of styrene (St) was achieved by using TMPCl/TiCl4/Ti(OiPr)4 initiating system from −80 to −50°C in a cost‐effective solvent mixture n‐Hexane/CH2Cl2 (v/v = 6/4). The –OiPr group was present in the form TiCl3(OiPr) for TiCl4/Ti(OiPr)4 ratio more than 3/1 and moderated the lifetime of the growing PS cation. Subsequently, Ti(OiPr)4 was added to the living charge of PIB initiated by initiator 1,4‐dicumyl chloride (DCC), followed by the addition of styrene monomer. The success of this developed synthesis methodology was confirmed by comparing the findings from GPC (Gel permeation chromatography) traces with and without the addition of Ti(OiPr)4. SIBS with nearly 30% weight content of PS (SIBS30) was successfully obtained with an optimally narrow MWD of 1.49 at −80°C by employing the TiCl4/Ti(OiPr)4 ratio of 6/1. Interestingly, SIBS30 with a very narrow PDI of 1.22 could be successfully synthetized at an elevated temperature of −60°C.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
A number of imidazole-based acidic (χ(LA)≥0.6) ionic liquids (RmimCl-LA, where R = Et or Bu, LA = AlCl3, AlBr3, iBuAlCl2, FeCl3, GaCl3, and BBr3) has been synthesized and their activity in cationic ...polymerization of isobutylene has been assessed. Among different ionic liquids tested here, emimCl-AlCl3, emimCl-FeCl3 and emimCl-GaCl3 showed the best results in terms of monomer conversion, exo-olefin end group content and polydispersity. It was shown that reaction rate depended strongly on the rate of partial hydrolysis of corresponding ionic liquid and increased in the following order: emimCl-FeCl3<emimCl-GaCl3<emimCl-AlCl3. It was demonstrated that emimCl-FeCl3 is the most promising catalyst for the synthesis of HR PIB with desired low molecular weight (Mn < 2500 g mol−1) and polydispersity (Mw/Mn < 2.5) and high content of exo-olefin end groups (>85%). However, due to poor dispergation of emimCl-FeCl3 in n-hexane as well as its high stability toward hydrolysis, the catalyst aging and/or sonication of reaction mixture is required in order to provide acceptable polymerization rate.
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•Acidic ionic liquids are promising catalysts for the synthesis of highly reactive polyisobutylene.•Catalyst aging and/or sonication of reaction mixture leads to significant increase of the reaction rate.•EmimCl-FeCl3 affords polyisobutylene with desired low Mn (<2500 g mol−1) and polydispersity (Mw/Mn < 2.5).•Polyisobutylene with high content of exo-olefin end groups (>85%) was obtained at IB = 5.2 M and high temperature (>0 °C).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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