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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We describe the synthesis, characterization, and select properties of a novel polyurethane (PU) prepared using a new polyisobutylene diol, HO‐CH2CH2‐S‐PIB‐S‐CH2CH2‐OH, soft segment and conventional hard segments. The diol is synthesized by terminal functionalization of ally‐telechelic PIB followed by low‐cost thiol‐ene click chemistry. Properties of ‐S‐ containing PU (PIBS‐PU) containing 72.5% PIB were investigated and compared to similar PUs made with HO‐PIB‐OH (PIBO‐PU). Hydrolytic resistance was studied by contact with phosphate‐buffered saline, oxidative resistance by immersing in concentrated HNO3, and metal ion oxidation resistance by exposure to CoCl2/H2O2. Hydrolytic and oxidative resistances of PIBS‐PU and PIBO‐PU are similar and superior to a commercial PDMS‐based PU, Elast‐Eon™ E2A. According to 1H NMR spectroscopy the ‐S‐ in PIBS‐PUs remained unchanged upon treatment with HNO3, however, oxidized mainly to ‐SO2‐ by CoCl2/H2O2. Static mechanical properties of PIBS‐PU and PIBO‐PU are similar, except creep resistance of PIBS‐PU is surprisingly superior. The thermal stability of PIBS‐PUs is ∼15 °C higher than that of PIBO‐PU. FTIR spectroscopy indicates H bonded S atoms (N‐H…S) between soft and hard segments, which noticeably affect properties. DSC and XRD studies suggest random low‐periodicity crystals dispersed within a soft matrix. Energy dispersive X‐ray spectroscopy–scanning electron microscopy indicates homogeneous distribution of S atoms on PIBS‐PU surfaces. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1119–1131

Sulfur-containing polyisobutylene (PIB)-based polyurethane nanocomposite (PIB s -PU/NC) was synthesized using HOACH 2 CH 2 ASAPIBASACH 2 CH 2 AOH for the soft segment, conventional hard segments of MDI and BDO, and organically modified montmorillonite (OmMMT) nanolayers. The properties of PIB s -PU/NC containing 72.5% PIB and 0.5% OmMMT were studied and contrasted with unmodified PIB s -PU. PIB s -PU/ NC produces colorless optically clear films exhibiting enhanced tensile strength, elongation, oxidative-hydrolytic stability, and creep resistance relative to that of PIB s -PU. FTIR spectroscopy indicates H bonded S atoms between soft and hard segments, and OmMMT nanolayers. DSC and XRD suggest randomly dispersed low-periodicity crystals and urea groups between galleries. We propose that minute amounts of OmMMT nanolayers become covalently attached to polyurethane chains and beneficially affect properties by acting as co-chain extender/reinforcing filler.

We report the synthesis of high-molecular-weight linear polyisobutylenes (PIBs) and PIB networks from low-molecularweight PIB by thiol-ene click chemistry. Thus, liquid allyl-telechelic PIB was reacted with small di-and tri-thiols, and the thiolated intermediates chain-extended by UV-or thermally induced free radical initiation to linear and crosslinked products. PIB networks were also prepared by crosslinking SH-telechelic PIB with a small triallyl compound. Linear products were characterized by 1 H NMR spectroscopy and GPC, and networks by FTIR spectroscopy, extractables, swelling, and permanent set. The effect of reaction conditions (nature of thiol chain extender, concentration of photo-and thermal initiators, UV radiation time, and reagent concentrations) on chain extension and crosslinking was investigated. Under well-defined conditions high-molecular-weight PIBs and tight PIB networks were prepared. Thiol-ene click chemistry provides novel thiolated PIB derivatives and is a useful strategy for the convenient preparation of high-molecular-weight rubbery PIBs and tight PIB networks from low-molecular-weight PIB precursors.