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A series of polyurethane elastomers ( PUEs) derived from three thiacalix[4]arene derivatives ( TC4As), namely p-tert-butylthiacalix[4]arene, tetrasodium thiacalix[4]arenetetrasulfonate and thiacalix[4]arenetetrasulfonic acid, as a portion of chain extender in a mixture with glycerol were synthesized. The effects of the chemical structure of TC4As used as chain extenders on the various properties of the prepared PUEs were investigated and compared with PUE extended with only glycerol as chain extender using Fourier transform infrared ( FTIR) spectroscopy, differential scanning calorimetry ( DSC), thermogravimetric analysis ( TGA), X-ray diffraction ( XRD), scanning electron microscopy and a universal tensile tester. Moreover, the effect of the introduction of TC4As as a portion of chain extender on the hydrophobicity of the PUEs was also evaluated. DSC, FTIR spectroscopy and XRD revealed that the degree of phase separation and crystallinity in TC4A-based PUEs was much higher than that of the glycerol-based ones. Thus, it was concluded that the presence of TC4As in TC4A-based PUEs seems to favour the formation of a more ordered structure due to an increase in the degree of phase separation. The TGA results also showed that, with incorporation of TC4As into the polyurethane backbone, the thermal stability of PUEs was improved. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

In this study, biocompatible magnetic FeO/polyurethane elastomer nanocomposites were synthesized using in situ polymerization method. Pure FeO nanoparticles were synthesized by coprecipitation method and characterized by X-ray diffraction, Fourier transform infrared (FTIR), vibrating sample magnetometer and transmission electron microscopy. The chemical structure, thermal properties, and mechanical properties of the FeO/PU nanocomposites, as well as the evaluation of effect of nanoparticles content on thermal and mechanical properties, were studied by FTIR, thermogravimetric analyzer (TGA), dynamic mechanical thermal analysis (DMTA), and tensile analysis. The dispersion and morphology of the nanoparticles in the nanocomposites were studied by scanning electron microscopy (SEM) technique. SEM results confirmed that nanoparticles tend to be more agglomerated in polyurethane matrices with increasing of nanoparticles content. TGA analysis also showed a decrease in the thermal stability of FeO/polyurethane nanocomposites compared to pure polyurethane, which was attributed to disruption of hydrogen bonds between polyurethane chains by FeO nanoparticles. DMTA results also showed an increase in glass transition temperature of FeO/PU nanocomposites compared to pure polyurethane. Biocompatibility studies demonstrated that fabricated nanocomposites can be good candidates for biomedical application. [ABSTRACT FROM AUTHOR]

The effect of structural chemistry of different soft segments on various structural properties of polyurethane-urea (PUU) elastomers was evaluated in this study. A series of PUU elastomers were prepared by the reaction of 4,4'-diisocyanato dicylohexylmethane (H12MDI) with polycaprolactone (PCL), Polytetramethylene glycol (PTMG), Polyethylene glycol (PEG), Polybutylene adipate (PBA) and amine chain extender 4,4'-methylenebis(2,6-diethylaniline) (MBDEA). Fourier transform infrared (FTIR) spectroscopy was used to study the synthesis of final PUU elastomers. Thermal behaviour of PUU elastomers was investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis. The surface properties and hardness of elastomers were characterized by measuring contact angle and hardness in shore A scale. The results showed highest thermal stability and hydrophobicity of PUPCL i.e., Polycaprolactone polyol based PUU elastomer. The proposed synthesis of PUU elastomers was confirmed by the appearance of -NH peak at 3305-3315 cm-1 and disappearance of -NCO peak at 2270 cm-1 in FTIR spectra. [ABSTRACT FROM AUTHOR]

Magnetic polyurethane elastomer nanocomposites were prepared by incorporating pure and thiodiglycolic acid (TDGA) surface-modified Fe3O4 nanoparticles into polyurethane matrix using in situ polymerization method. Surface modification of Fe3O4 nanoparticles was carried out to enhance the dispersion of the nanoparticles in polyurethane matrix. Pure and TDGA surface-modified Fe3O4 nanoparticles were synthesized by coprecipitation method and characterized by Fourier Transform Infrared Spectroscopy, X-ray diffraction, and Vibrating Sample Magnetometer. The morphology and dispersion of the nanoparticles in the magnetic polyurethane elastomer nanocomposites were studied by Scanning Electron Microscope. It was observed that surface modification of Fe3O4 nanoparticles with TDGA enhanced the dispersion of the nanoparticles in polyurethane matrices. Furthermore, effect of surface modification of Fe3O4 nanoparticles on thermal and mechanical properties of magnetic polyurethane elastomer nanocomposite was investigated by thermogravimetric analysis, dynamic mechanical thermal analysis, and an Instron type Tensile Tester. It was concluded that surface modification of Fe3O4 nanoparticles allowed preparation of the magnetic nanocomposites with better mechanical properties. Moreover, study of fibroblast cells interaction with magnetic nanocomposites showed that the products can be a good candidate for biomedical application due to their in vitro biocompatibility and non-toxicity. [ABSTRACT FROM AUTHOR]

Highlights: [•] Novel elastomeric samples were prepared from cationic polyurethanes and alginate. [•] Extremely stretchable properties appeared for prepared samples. [•] Novel nanoparticles of sodium alginate were found in micro-structure studies. [•] Excellent compatibility was shown for samples containing alginate below 10%. [Copyright &y& Elsevier]

The article presents the conducted study to analyze the chemical structures of the biodegradable polyurethane (PU) elastomers that were synthesized through the reaction of poly(&#x03B5-caprolactone) (PCL) and isophorone diisocyanate (IPDI), which are extended with various mass ratio of chitosan and 1,4-butane diol (BDO). The methods used in the study include the Fourier transform infrared (FTIR) spectrometry, thermogravimetric analysis (TGA) and X-ray diffraction (XRD). The properties that were examined include crystallinity.

Abstract: Chitin based polyurethane (PU) elastomers constituted on 4,4´-diphenylmethane diisocyanate (MDI), poly(ε-caprolactone) (PCL) and extended with blends of chitin/1,4-butane diol were synthesized via two step polymerization technique. The synthesized samples were irradiated for 50, 100 and 200h in an UV exposure chamber as such the spectral distribution of the light is good match for terrestrial solar radiation. The crystalline behavior of the irradiated PU samples were investigated by X-ray diffraction (XRD), differential scanning calorimetery (DSC) and dynamic mechanical thermal analysis (DMTA) techniques. The effect of irradiation time and chitin contents on crystallinity were studied and investigated. The maximum decrease in the crystalline behavior of samples after irradiation observed by XRD, DSC and tan δ peaks were found for the PU samples extended with lower contents of chitin (chitin/BDO; 0/100). In comparison with irradiation times the 200h irradiation showed maximum change in the crystalline behavior. [Copyright &y& Elsevier]

Abstract: Biodegradable polyurethane elastomers with tunable hydrophobicity were synthesized by step-growth polymerization techniques using poly(ɛ-caprolactone) (PCL) and 4,4′-diphenylmethane diisocyanate (MDI). The prepolymer was extended with different mass ratios of chitin and 1,4-butane diol (BDO). The effect of chitin contents in chain extenders (CE) proportion on surface properties was studied and investigated. Incorporation of chitin contents into the final PU showed decrease in surface free energy and its polar component. Simultaneously, the work of water adhesion to polymer decreases significantly by increasing the chitin contents in the synthesized polymer. Contact angle measurement, water absorption and swelling behavior of the synthesized polyurethane samples were affected by varying the chitin contents in the chemical composition of the final PU. The interactions of the final PU films with solvents on the surface were displayed clear dependent on the contents of chitin in to the final polyurethane formulation. The results of different tests demonstrated that the synthesized products are a potential candidate as non-absorbable suture as previously investigated into their in vitro biocompatibility and non-toxicity [K.M. Zia, M. Zuber, I.A. Bhatti, M. Barikani, M.A. Sheikh, Int. J. Biol. Macromol. 44 (2009) 18–22]. [Copyright &y& Elsevier]

Abstract: Shape memory polyurethanes (SMPUs) were prepared from polycaprolactone diol 4000 (PCL 4000), 1,4-butanediol (BDO), chitin, dimethylol propionic acid (DMPA), triethylamine (TEA) and 4,4′-diphenylmethane diisocyanate (MDI), and the structures of the synthesized materials were verified by infrared spectroscopy. The effects of chitin and DMPA contents in the polyurethane formulation on surface properties were investigated. DMPA provides function of making hydrophilic polyurethanes. The crystalline structure of chitin enhanced the hydrophobicity of the synthesized materials. Contact angle, water absorption, surface free energy, work of water adhesion and swelling behavior of the synthesized polyurethanes were affected by varying the DMPA and chitin contents. The interactions of the PU films with solvents on the surface were clearly related to the contents of DMPA and chitin in the final polyurethane formulation. [Copyright &y& Elsevier]

Abstract: A series of polyurethane elastomers were prepared by the reaction of poly ε-caprolactone and 4,4′-diphenylmethane diisocyanate. The prepolymer was extended using α, ω-alkane diols as chain extenders having 2–10 methylene units in their structure. The synthesized samples were irradiated for 50, 100 and 200h in an ultra violet (UV) exposure unit. Modifications in the chemical structure before and after irradiation were characterized using Fourier Transform Infrared spectroscopy. The thermal and mechanical properties were affected by the ultra violet irradiation time and the number of methylene units in the chain extenders. The experimental results indicated that the morphological structure changed during irradiation as a consequence of hard segment and soft segment degradation. [Copyright &y& Elsevier]

Abstract: Chitin based polyurethane elastomers (PUEs) were synthesized by step growth polymerization techniques using poly (ε-caprolactone) (PCL), 4, 4′- diphenylmethane diisocyanate (MDI) and blends of chitin and 1,4-butanne diol (BDO). The conventional spectroscopic characterization of the samples with FT-IR, 1H NMR and 13C NMR were in accordance with proposed PUEs structure. The crystalline behavior of the synthesized polymers were investigated by X-ray diffraction (XRD), differential scanning calorimetery (DSC), optical microscopic technique and loss tangent curves (tan δ peaks). Results showed that crystallinity of the synthesized PUEs samples was affected by varying the chitin contents used as chain extender. The contents of chitin favors the formation of more ordered structure, as higher peak intensities were obtained from the PU extended with chitin than 1,4-butane diol (BDO). X-ray diffraction experiments results correlates with optical microscopy findings. The higher ΔH value; 41.57(Jg−1) was found in the samples extended with chitin than BDO (31.32Jg−1). [Copyright &y& Elsevier]

Abstract: Polyurethane elastomers (PUEs) based on 4,4′-diphenylmethane diisocyanate (MDI), poly (ɛ-caprolactone) (PCL) and extended with series of chain extender (CE) were synthesized via two step polymerization technique. The synthesized samples were irradiated for 50, 100 and 200h in an UV exposure unit as such the spectral distribution of the light is good match for terrestrial solar radiation. The modifications in the chemical structures of the PU before and after irradiation were characterized using Fourier transform infrared (FT-IR) technique. The effect of irradiation time and chain extenders length on surface properties were studied and investigated. Photo-oxidation of PU surface leads to fast increase in surface free energy and its polar component. Simultaneously, the work of water adhesion to polymer increases significantly during UV-irradiation. The higher changes in surface properties, observed by water absorption (%), equilibrium degree of swelling, as well as monitored by ATR-FT-IR and contact angle measurement, were found for the PU samples extended with higher number of methylene unit and irradiation time. [Copyright &y& Elsevier]

A series of polyurethane elastomers (PUEs) based on 4,4′-cyclohexamethylene diisocyanate (H 12 MDI)/1,2-ethanediol as hard segment with the soft segments having different molecular weights of polycaprolactone diols, were effectively polymerized by two step technique. The structural characterization was performed by FT-IR spectroscopy. The X-ray diffraction (XRD) technique was used to study the crystallinity and hydrophilicity of the prepared polymer films. It was found that crystallinity and hydrophilicity increased with increasing the chain length of soft segments. The effect of molecular weight of polyols on the contact angle, water absorption (%) and swelling behavior of the synthesized polyurethanes were also studied. Moreover, the scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques revealed that the degree of micro-phase separation increases with increasing molecular weight of polyol which confirmed the results pattern shown by XRD diffractogram. [ABSTRACT FROM AUTHOR]

Abstract: Chitin-based polyurethane elastomers having potential for biomedical applications with tunable mechanical properties were synthesized by step growth polymerization techniques using poly(ɛ-caprolactone) (PCL) with different diisocyanates. The prepolymer was extended using chitin and/or 1,4-butane diol (BDO). The structures of the resulted polymers were determined by Fourier transform infrared (FTIR), 1H NMR and 13C NMR spectroscopic techniques. The effect of structure of diisocyanates and chain extenders on mechanical properties and in vitro biocompatibility were investigated. The results revealed that the final polymers extended with chitin are preferred candidates for surgical threads with on going investigations into their in vitro biocompatibility and non-toxicity. [Copyright &y& Elsevier]