Lanxess (Canada)

Graphene oxide (GO), NaF and CaCl2 were mixed in their aqueous solutions to obtain a GO–CaF2 hybrid with CaF2 particles uniformly dispersed on GO surface, and further in situ reduced by hydrazine to obtain reduced-GO (RGO)-CaF2 hybrid. RGO–CaF2/brominated butyl rubber (BIIR) composites were obtained by solution mixing, in which RGO–CaF2 was well dispersed in nano-sized as confirmed by transmission electron microscope images. The RGO–CaF2/BIIR composites had much better mechanical properties than BIIR. The stress at 300% extension of BIIR increased 72% after the addition of 3 parts per hundreds of rubber (phr) RGO–CaF2. The improved mechanical properties benefited from the strong interaction between RGO and BIIR. The dielectric constant of RGO–CaF2/BIIR composites increased with increasing RGO–CaF2 loading. Because of the synergistic effect of RGO and CaF2, the stresses at various extensions, dielectric constant and thermal conductivity of RGO–CaF2/BIIR composites were higher than those of RGO/BIIR or CaF2/BIIR composites. The improved mechanical, dielectric and thermal properties bring BIIR the potential to be used in a wider range of application areas.

Butyl rubber-poly(ethylene oxide) (PEO) graft copolymers with high PEO content (40–83 wt %) were synthesized by the functionalization and activation of the double bond moiety of butyl rubber containing high (7 mol %) isoprene content and subsequent reaction with PEO of different molecular weights from 750 to 5000 g/mol. The properties of these copolymers, along with other butyl rubber-PEO graft copolymers were studied in films and in aqueous solution. Despite the high PEO content, films of the copolymers were quite stable in water with respect to mass loss and were capable of releasing an encapsulated probe molecule in a manner that was dependent on the PEO content. At high PEO content they were resistant to the adhesion and growth of C2C12 cells. Despite the resistance of films to dissolution, it was possible to prepare nanosized aqueous assemblies via a THF-water exchange process and the sizes of the assemblies were tuned by their method of preparation. The assemblies were also able to encapsulate a probe molecule and were found to be nontoxic in vitro. Combined, this set of properties makes these new amphiphilic copolymers promising for a wide range of potential applications. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3383–3394

Abstract Allylic halide displacement from brominated poly(isobutylene‐co‐isoprene) (BIIR) by carboxylate nucleophiles is used to prepare elastomer derivatives containing pendant polymerizable functionality. These solvent‐borne substitutions are conducted under homogeneous and phase‐transfer catalyzed reaction conditions to synthesize acrylate and vinylbenzoate esters in high yield. The resulting macro‐monomer derivatives are shown to crosslink efficiently with peroxide initiation to give high modulus, thermoset products that cannot otherwise be accessed from isobutylene‐rich elastomers. The extent of cure, as measured by the storage modulus of the vulcanizate, scales with RCH=CH2 content, and can be extended by co‐oligomerization of pendant unsaturation with that contained within multifunctional coagents. An alternate approach involving the introduction of pendant sulfonyl azide functionality is described, wherein thermal decomposition to nitrene intermediates supports an efficient crosslinking process. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

Abstract This article discusses the characterization of arborescent (hyperbranched) polyisobutylenes (arb‐PIBs) by size exclusion chromatography and differential scanning calorimetry, in comparison with linear PIB standards. The radius of gyration (〈r〉1/2 = Rz), measured from the angle dependence of light scattering of high‐molecular‐weight arb‐PIBs, was significantly larger than the hydrodynamic radius (Rh) from size exclusion chromatography/viscometry, and the Rh values were significantly smaller than Rh of linear PIBs. The glass‐transition temperature of arb‐PIBs having a branch molecular weight higher than the critical entanglement molecular weight was dependent on both the total number‐average molecular weight and BR up to BR ∼ 15. A modified Fox–Flory equation is proposed to describe the effect of architecture on the thermal transition. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1770–1776, 2006