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[Display omitted] • Self-healing and recyclable thermosetting polyurethane composites (EPB) were synthesized through the Diels-Alder reaction. • The tensile strength of EPB with 0.5 wt% MBI is 54 MPa. • The recycled EPB can still maintain 93.3 % of its mechanical performance. • The V oc and I sc of the EPB-based TENG were 89 V and 3.6 μA, respectively. Improving the mechanical properties, self-healing capabilities, and recyclability of friction layer materials is crucial for the advancement of high-performance triboelectric nanogenerators (TENG). In this study, self-healing cross-linked polyurethanes were synthesized through the prepolymer technique, employing the Diels-Alder (D-A) reaction between the furan ring and Bismaleimide (BMI). The tensile strength of PU film with 10 wt% MBI is 54 MPa, and the shape recovery rate is 96.99 %. Moreover, it exhibits excellent self-healing and recyclable characteristics. Surface cracks can be healing within 10 min under heat, reshaped through hot pressing, while retaining 93.3 % of its mechanical properties. Additionally, the 2 cm × 2 cm area PU-based TENG can generate a short-circuit current, open-circuit voltage, transferred charge, and power density of 3.6 μA, 89 V, 29 nC, and 2.5 W/m2, respectively, at a frequency of 1 Hz. Futhermore, the self-healing efficiency of mechanical properties and the triboelectric output performances were found to reach 93.3 % and 98 %, respectively, after reprocessing. This study introduces a promising method for enhancing self-healing, shape memory characteristics, and the design of wearable TENG devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Imidazole-modified carboxygraphene was introduced into polyurethane coatings with disulfide bonds to successfully synthesize IAAC. • F-PUSS had outstanding anticorrosion function. • F-PUSS had excellent antibacterial and anti-algae functions. • F-PUSS showed distinguished self-healing function at 60 ℃. Marine corrosion and biofouling present significant challenges to maintaining maritime vessels and oceanic infrastructure. Developing coatings that integrate anti-fouling, anti-corrosion, and self-healing properties remains a critical issue. This study introduces imidazolium-modified carboxylated graphene (FCGO) into polyurethane coatings (F-PUSS) containing disulfide bonds to address this challenge. The incorporation of FCGO significantly enhances the mechanical properties of the coating, improving tensile stress by 40 % to 20.97 MPa. The barrier properties of FCGO also provide strong corrosion resistance, with |Z| 0.01Hz values an order of magnitude higher than the original samples, even after 15 days of immersion in sodium chloride (3.5 wt%). Additionally, F-PUSS retains corrosion resistance after repairs. The synergistic action of imidazole groups and graphene provides excellent antifouling performance with nearly to an alga rate of 100 % and an antimicrobial rate of 96 %. F-PUSS demonstrates remarkable self-healing capabilities, with a healing efficiency of 78 % after 48 h at 60 °C. This study provides valuable insights for designing multifunctional polymer materials with anti-fouling, anti-corrosion, and self-healing functions. [ABSTRACT FROM AUTHOR]

[Display omitted] • A super strong DAPU with efficient self-healing enabled by partially mixing reversible DA bonds was synthesized. • The tensile strength of DAPU reached up to 65 MPa and the elongation at break up to 1053 % with the toughness of 216 MJ/m3. • The self-healing process was completely healed in 2 h at 110 °C and the self-healing degree reached 95 %. The reversible chain extender Diels-Alder-diol (DA-diol) containing thermally dissociable Diels-Alder adducts (DA adducts) was synthesized and combined with 1,4-butanediol (BDO) as complexed chain extenders used for preparing a transparent polyurethane elastomer (DAPU) with high mechanical strength and efficient self-healing ability by partially mixing reversible hard domains. The optimal DAPU occupies a desired high tensile strength of 65 MPa, and its elongation at break and toughness are of 1050 % and 216 MJ·m−3, respectively. Meanwhile, the DAPU-0.2 elastomer heals at 110 °C for 2 h with a healing efficiency of 95 %. The desirable mechanical strength and efficient self-healing ability are attributing to the BDO chain extended hard segments ensure the high strength at room temperature, while DA-diol chain extended hard segments endow the as-prepared DAPUs with self-healing ability at an elevated temperature. This work overall points to a strategy in designing self-healing polyurethane elastomers with markedly improved mechanical strength and efficient self-healing ability by partially mixing reversible hard domains. [ABSTRACT FROM AUTHOR]

[Display omitted] • High mechanical strength and toughness polyurethane-based thermally conductive composite was prepared. • Mechanical and thermal property are notably affected by the isocyanate index. • Composite with an isocyanate index of 1 exhibited the exceptional comprehensive property performance. • Mixed failure mode obtained the highest tensile lap-shear strength. New requirements for thermal interface materials to combine both mechanical properties and heat dissipation have been proposed by long cruising range and lightweight cell-to-pack (CTP) battery system. Here we report an environment-friendly thermally conductive composite based on polyurethane (PU) as the matrix and alumina (Al 2 O 3) as the thermally conductive filler, which presented all of the thermally conductive, notable mechanical strength and toughness, and electrical insulation with a thermal conductivity of 0.84 W/(m·K), a tensile strength of 8.09 MPa, an elongation at break of 117.51 %, and a volume resistivity of 4.3 × 1014 Ω·cm. Aluminum alloy 5052 adherends were used to manufacture the single-lap joints (SLJs) of composites with different isocyanate indices, and the single-lap shear test was used to investigate the tensile lap-shear strengths and failure modes of the joints. A critical discussion was conducted regarding the relationship between the isocyanate index (R index) and the bonding mechanism. It was found that changing the isocyanate index under the premise of fixed hard segment content enhanced the lap-shear strength of joints from 4.49 MPa to 8.24 MPa. Meanwhile, the failure mode transitioned from the adhesive failure mode to the adhesive/cohesive mixed failure mode, and then to the cohesive failure mode. Hence, the present study sheds light on the rational design of thermally conductive composites to promote the multi-functionality of thermal management applications in the new energy vehicle battery domains. [ABSTRACT FROM AUTHOR]

[Display omitted] • A self-healing and conductive polyurethane was constructed based on coordination interactions. • The polyurethane displayed well fatigue resistance and recyclability. • The polyurethane indicated fast response and stable sensing to varied human motions. Polyurethane elastomers were considered as an ideal material for flexible devices. However, the application of polyurethane elastomers was still largely limited by the disadvantages of poor self-healing property and low conductivity. In this work, a self-healing polyurethane with adjustable mechanical performances was constructed via the introduction of reversible dynamic interactions in the polyurethane matrix, such as metal ion-tripyridine coordinations, disulfide bonds and hydrogen bonds. And lithium salt was incorporated into the polyurethane to achieve ionic conductivity. The obtained polyurethane exhibited adjustable breaking strength with a range of 0.77 ∼ 10.75 MPa, breaking elongation in the range of 1719 ∼ 1863 %, and conductivity in the range of 0.08 ∼ 1.57 × 10−3 S/m by adding different LiTFSI (5 ∼ 35 wt%) into the polyurethane. In addition, the polyurethane displayed efficient self-healing behavior, well fatigue resistance, and recyclability. Also, the polyurethane showed great application prospects as flexible sensors by performing stable and sensitive responses to a wide range of human body movements. [ABSTRACT FROM AUTHOR]

• PU/SiO 2 film with vertical differential density. • Controllable self-rolling behavior. • Reversible and tunable shape of self-rolling film as actuator. In this paper we report a new kind of self-rolling polyurethane (PU) film with the vertical gradient structure – top solid PU layer and bottom PU/SiO 2 hybrid layer. The differential swelling properties of these two layers allow the film to exhibit reversible shape transformation upon exposure to different solvents and their mixtures. We investigated correlation between shapes (tube/scroll/spiral) formed upon self-rolling and the size/shape of the films, fraction of silica particles, the aspect ratio of the film, and the external solvents. We have also found that Timoshenko bilayer model allows prediction of rolling behavior basing on properties of each layer. The reversible self-rolling behavior of the bilayer films with differential structure is expected to allow development of new actuator in the near future. [ABSTRACT FROM AUTHOR]

• Fluoride-responsive degradable unit can be incorporated into PUs with a range of adhesive properties. • The mechanical properties can be tuned by varying structure and density of H-bonding monomers. • Introducing crystallinity into the adhesives can lower the bonding temperature to 50 °C. • The adhesives undergo depolymerisation to facilitate debonding on addition of fluoride ions. This paper reports the solvent-free synthesis of a series of six fluoride responsive debond-on-demand polyurethane (PU) adhesives that contain a silyl functionalised degradable unit (DU). To optimise the adhesion strength and debonding nature of the adhesives, the chemical composition of the PUs was varied according to the structure of the polyol or the diisocyanate component in the polymer mainchain. 1H NMR spectroscopy was used to study the depolymerisation behaviour in solution state. It showed that tetra -butylammonium fluoride (TBAF) triggered the breakdown of the DU unit without fragmenting the polyol mainchain indiscriminately. On exposure to fluoride ions, the PUs underwent depolymerisation with reductions in M n ranging from 64 to 90% as measured by GPC analysis. The morphology and thermal properties of the PUs were characterised by differential scanning calorimetry (DSC), rheology and variable temperature (VT) SAXS/WAXS analysis. Each technique demonstrated the reversibility of the supramolecular polymer network under thermal stimuli. PUs containing poly(butadiene) soft segments were amorphous with glass transition and viscoelastic transition temperatures dependent on the nature of the soft segment and diisocyanate starting materials. The PU containing a polyester soft segment exhibited a defined melting point at 49 °C. Mechanical stress-strain analysis of the series of PUs showed each exhibited greater than 70% reduction in toughness after treatment with TBAF for 30 min as a consequence of the chemo-responsive degradation of the polymer mainchain. The material featuring an ester-based polyol demonstrated excellent adhesion at bonding temperatures as low as 60 °C. Moreover, this material could be thermally rebonded if broken by force without loss in adhesion strength over three debond-rebond cycles. Lap shear adhesion tests showed a reduction in adhesive strength of approximately 40% (from 11.4 MPa to 7.3 MPa) on exposure to fluoride ions. [ABSTRACT FROM AUTHOR]

[Display omitted] • The limitations and developmental directions of polyurethane materials in cardiovascular therapy are reviewed. • The mechanisms underlying the poor biostability of polyurethane materials are elucidated, and research progress in corresponding enhancement methods is provided. • Modification methods to enhance polyurethane for use in cardiovascular materials are discussed. • The macroscopic morphology and processing techniques required for polyurethane materials in cardiovascular applications are discussed. The long-term stability and safety of polymeric vascular grafts, particularly those made of polyurethane, have been a major concern due to biodegradation problems and biocompatibility issues. This review aims to provide an overview of the development history, performance characteristics, and current status of polyurethane vascular grafts. Specifically, it focuses on the biological performance issues associated with polyurethane materials used in artificial vascular applications. Additionally, the review outlines various surface modification methods that have been employed to improve the biocompatibility of polyurethane and discusses the advancements made in the process technology of new polyurethane vessels. By utilizing modification strategies, polyurethane has been transformed from an inert material to a bioactive material. Furthermore, electrospinning technology has further enhanced the performance of polyurethane in vascular applications. Finally, the potential of polyurethane materials for clinical applications in vascular medicine is evaluated. [ABSTRACT FROM AUTHOR]

[Display omitted] • Innovative use of Nano Ni@C particles that are commonly used as electrode materials as filler to strengthen polyurethane materials. • The synthesized polyurethane nanocomposites also have adjustable magnetic properties due to the loading of magnetic particles. • The synthesized polyurethane nanocomposites combines good mechanical properties and self-healing properties. Widely employed as polymers, polyurethanes also struggle to strike a balance between mechanical and self-healing qualities. Extrinsic self-healing can readily result in the production of material defects and stress concentration, which can result in the loss of mechanical property. In this study, self-healing and mechanical properties were combined to create a self-healing polyurethane nanocomposite film (PUHN) with good fatigue resistance. Reversible hydrogen and disulfide bonds were introduced to the polyurethane film, meanwhile, carbon-coated nickel nanoparticles were dispersed into the matrix as fillers during the early stage of polymerization. The results showed that PUHN combines outstanding mechanical properties with excellent self-healing properties, while the tensile strength of PUHN was increased by 38 % to 2.32 MPa due to the small-size effect caused by the introduction of nanoparticles. The introduction of reversible disulfide bonding and the presence of abundant hydrogen bonding give PUHN excellent self-healing properties, which can reach 91.2 % self-healing efficiency after 3 h in an oven at 80℃. Meanwhile, the fatigue resistance of the composite material also shows considerable application potential for use in packaging. [ABSTRACT FROM AUTHOR]

[Display omitted] • Valorization of monomers from different potential sustainable resources. • Chemical modifications of new sustainable aromatic diols for polyurethane synthesis. • Full thermal and mechanical characterizations of aromatic polyurethanes. • Novel macromolecular architectures-properties relationships analysis. Thermoplastic polyurethanes (TPUs) are known for their versatility due to the wide range of macromolecular architectures available. This study focuses on the synthesis and the architecture-properties relationships of new sustainable aromatic TPUs, derived from different potential sustainable resources, such as biomass and plastic waste. Thus, new sustainable aromatic short diols were synthesized from 4–hydroxybenzoic acid and syringic acid, and named HB.diol and Syr.diol, respectively. Subsequently, TPUs were prepared with these original diols as chain extenders, alongside conventional aromatic and aliphatic sustainable chain extenders, like 1,4–benzenedimethanol (BDM) and 1,4-butanediol. The investigation explored the effect of these chain extender structures on the properties of the resulting TPUs, using both aromatic and aliphatic diisocyanates in the synthesis. The thermal and mechanical characteristics of the TPUs were evaluated to identify key structural parameters that influence the properties of the macromolecular architectures. Notably, the presence of aromatic rings enhanced the incompatibility between soft and hard segments (HS), resulting in greater phase segregation. Ether bonds in HB.diol and symmetric structures in BDM enhanced hydrogen bonding, promoting the development of organized and crystalline HS, enhancing phase segregation, thus improving thermo–mechanical and mechanical properties. On opposite, methoxy groups in Syr.diol and the asymmetry of the aromatic diisocyanate hindered the organization of HS, leading to reduced TPUs structuration and lower mechanical properties. Overall, these findings highlight the potential for creating sustainable TPU macromolecular architectures with desirable properties by selecting appropriate raw materials. [ABSTRACT FROM AUTHOR]

• The polymerization strategy is effective for telechelic polyurethane synthesis. • The n amine /n isocianate molar ratio determines the polymerization rate. • Molar mass can be kinetically predicted. • The molar mass dispersity is smaller than 1.5. • Telechelic polyurethanes can be used as building blocks for block copolymer. Polyurethanes (PU) constitute one of the most versatile class of polymers with respect to composition, properties and applications. However, there are a lack of synthetic strategies capable of producing PU with controlled architecture, chain end functionality, molar mass and low molar mass dispersity (Ð); these characteristics could considerably improve the use of PU in advanced applications. In this study, we report a method for synthesizing polyurethanes based on the dissociation equilibrium of hindered urea groups. Diisopropylamine reacts promptly with isocyanates, forming hindered ureas in a dynamic fashion and establishing a dissociation equilibrium shifted towards hindered urea formation. The equilibrium reduces the concentration of isocyanates susceptible to the polyaddition with diols and, therefore, the step growth polymerization follows a controlled pathway resulting in PU with Ð < 1.3 and a weight average molar mass up to 5 kDa for bulk polymerization. Moreover, urea chain end functionality is maintained after purification and telechelic PU can be obtained for further use, such as the synthesis of block copolymers capable of self-assembly. [ABSTRACT FROM AUTHOR]

• The PU/SF composite porous film act as a support for decoration with Ag@AgCl NPs. • The Ag@AgCl-PU/SF exhibit a good photocatalytic activity on degradation of RhB under the UV and visible light. • The Ag@AgCl-PU/SF has a good antibacterial activity against S. aureus and E. coli. • The Ag@AgCl-PU/SF can be recycled easily without centrifugation and filtration. • The prepared processes are conducted under normal temperature and pressure and no need of special equipment. An efficient Ag@AgCl-polyurethane/silk fibroin (Ag@AgCl-PU/SF) composite photocatalyst was synthesized by an eco-friendly and practical multistep route, including a wet phase inversion technique, to prepare polyurethane/silk fibroin (PU/SF) composite porous films as a substrate. An impregnation-precipitation-photoreduction process was used to decorate Ag@AgCl nanoparticles in situ on the PU/SF composite porous films. The obtained samples exhibited high photocatalytic activity for the degradation of Rhodamine B (RhB) under ultraviolet and visible light. Meanwhile, the photocatalytic activity of the samples decreased only slightly after 4 runs of photodegradation of RhB. Importantly, the Ag@AgCl-PU/SF films could be recycled without centrifugation and filtration. The Ag@AgCl-PU/SF films also exhibited excellent antibacterial activity. Possible mechanisms for photocatalysis were proposed. This work may provide a new approach for the design of novel porous polyurethane film photoreactors that possess excellent photocatalytic and antibacterial activities for multifunctional applications. [ABSTRACT FROM AUTHOR]

• We developed a novel self-healing and shape memory polyurethane elastomer with superior mechanical properties by controlling the different molecular weight of the polyol and incorporating dynamic disulfide bonds for reversibility. • We have identified a potential application for the self-healing flexible substrate in flexible electronics. The self-healing polyurethane films have received significant attention due to their unique shape memory behaviors and the hydrogen bonding arising from the urethane linkages. However, it is still a challenge to develop self-healing polyurethane with transparent, high impact resistance, and excellent shape recovery and mechanical properties. In particular, polycarbonate-based polyurethane shows transparency, weatherability and excellent mechanical properties. In this work, transparent self-healing polyurethane film with robust mechanical properties (breaking stress of 26 MPa and elongation at break of 630%) was synthesized by controlling the different molecular weight of the polycarbonate diol and incorporating dynamic disulfide bonds for reversibility. As a result, the self-healing polyurethane film showed an excellent self-healing ability with 98% healing efficiency and excellent shape memory ability with a recovery efficiency of ˃92%. In addition, we have identified a potential application for the self-healing flexible substrate in flexible electronics because of their stable electrical resistance even upon mechanical deformation. [ABSTRACT FROM AUTHOR]

• Porous PU/PVA blend hydrogels were obtained by freezing-thawing method. • The obtained hydrogels provided hydrogen bonds and hydrophobic interactions. • Three steps: a fast, a slow and an equilibrium water swelling were observed. • The release of neomycin sulphate into a biological model media was studied. Polyurethane based hydrogels were successfully prepared by freezing–thawing method of polyurethane (PU)/poly(vinyl alcohol) (PVA) mixtures in aqueous solution. The new materials were characterized by ATR-FTIR and SEM, confirming that the PU/PVA blend hydrogels form a network structure through hydrogen bonds and hydrophobic interactions. According to SEM analysis, an increase in the surface pore numbers and size was observed with increasing the polyurethane amount into the hydrogels. The average diameter of the pores was estimated as being between 4.05 and 39.05 µm. The PU/PVA blend hydrogels showed a lower tensile strength than pure PVA hydrogel, due to the extent of hydrogen bonding occurrence during the freezing–thawing process which determines a variation of porosity. The highest value of water swelling (1675%) was obtained for the hydrogel blend containing 50% PU, whereas pure PVA showed much lower ability for water (640%). These results can be explained by a denser structure of PVA network formed by applying successive freezing–thawing cycles. Three steps of water swelling were evidenced for the PU/PVA blend hydrogels: a fast one, a slow one and an equilibrium phase. In vitro technique was used for release of neomycin sulphate into a biological media model. The present investigations of the new PU/PVA blend hydrogels indicate their possible application as matrices for drug delivery. [ABSTRACT FROM AUTHOR]

• High-pressure CO 2 sorption on polyol and isocyanate was monitored by FT-NIR. • Upon mixing, reaction under high pressure was monitored by FT-NIR. • Sorbed CO 2 slowed down synthesis reaction due to catalyst deactivation and dilution. • At 0.07 g/g CO 2 catalytic sites were saturated, only dilution further contributed. • CO 2 supercritical state is not relevant to the reaction kinetics. The effect of CO 2 on the polyurethane synthesis between a polyol and an isocyanate was studied by in situ near infrared spectroscopy in a newly developed instrumented foaming equipment. In particular, first two solutions, namely a polyol/CO 2 solution and an isocyanate/CO 2 solution were formed at high pressure and then, upon mixing, the synthesis was promoted, still under pressure. Near infrared spectroscopy in reflection mode was used to monitor both CO 2 sorption in the polyol and in the isocyanate and the polyurethane synthesis under pressure. Results revealed a significant slowing down effect by the sorbed CO 2 , apparently due to two concurrent mechanisms, namely catalyst deactivation and dilution. [ABSTRACT FROM AUTHOR]

• Polymer particles were stabilised into a PP by using a silica gel as NAD. • A NAD concentration of 1.5 wt% was enough for producing a PPP having 38.69 wt% of solids. • PPPs of low viscosity were developed. • A reaction temperature of 80 °C allowed the maximum SM conversion. • The vinyl grafting and the hydroxyl stabilization role of the NAD were demonstrated. Currently, the PU industry is developing new products with enhanced physical, mechanical and structural properties. One of the specialties that is attracting more and more attention from managers and enterprises all over the world are the PUs based on polymer polyether polyols (graft polyols). In this work, the synthesis of graft polyols was developed employing a non-aqueous dispersant (NAD) based on silica gel, which contains in its chemical structure segments with a great affinity for the solid polymeric particles and other segment having a strong affinity for the hydroxyl groups of the liquid polyol. The combination of both polar and non-polar characteristics ensures the stability of the resulting polymer dispersion and prevent the sedimentation and the coalescence of the polymer particles. By using this NAD it was possible to synthesize trifunctional polymer polyether polyol (PPP) from Styrene and containing up to 38.69 wt% of solids. The optimal reaction conditions have been stablished using a concentration of 1.5 wt% NAD, 4 wt% of initiator respect to the monomer amount and a polymerization temperature of 80 °C. The viscosity of the optimal PPP (1930 mPa·s) and the particle size (dv 0.5 of 5.427 μm and dn 0.5 of 1.711 μm) were in the range of graft polyols available in the market for similar solids content, with the additional advantage of employing a lower quantity of NAD and a softer reaction temperature than those employed in the industrial process (110 °C). [ABSTRACT FROM AUTHOR]

• Cationic polyurethanes with different ionic degrees are obtained by post-modification. • Ionic sites in the polymer result in a better aggregation of hard segments. • Intermolecular chain interactions strengthen with increasing the cationic content. A linear non-ionic hard-soft segmented polyurethane (PU0) was prepared by the prepolymer synthesis method. The isocyanate terminated prepolymer, formed by a short and rigid aromatic diisocyanate and a long flexible poly(tetramethylene oxide) (PTMO), was chain extended with a piperazine (PIP) diol derivative. The non-ionic polyurethane was then ionized by a post-modification method, i.e. alkylation of the piperazine nitrogen atoms, thus obtaining cationomers with three different ionization degrees, named PU10, PU50, PU80. The polymers were characterized by means of FT-IR spectroscopy, solution and solid state Nuclear Magnetic Resonance (NMR) spectroscopies, Differential Scanning Calorimetry (DSC) and ThermoGravimetric Analysis (TGA). The chemical structure of the obtained polymers and their cationic content was confirmed by solution state 1H NMR. It was found that the methylation occurs quantitatively up to 50% of the PIP nitrogen atoms and that, even if a large excess of methylating agent is used, in our operating conditions a maximum of 80% of the PIP nitrogen atoms are ionized. All the characterization techniques used suggested that an increasing ionization degree induces a better phase separation between hard and soft domains, with a lower amount of diisocyanate units dispersed in the soft phase. In particular, FT-IR showed that the introduction of ionic sites modifies the hydrogen bond network and induces a better aggregation of the rigid units. In addition, DSC showed that (i) the glass transition temperature values of the polymers decrease and tend to that measured for pure PTMO upon increasing ionization; (ii) a crystalline phase due to PTMO packing in ordered structures appears at the highest ionization degrees, similarly to pure PTMO. 1H Time-Domain NMR and 13C solid state NMR revealed an increase in PTMO mobility with increasing ionic content, in agreement with DSC results. The measurements of proton spin lattice relaxation times in both the laboratory (T 1) and rotating (T 1ρ) frames allowed limits on the size of the hard domains to be estimated. T 1ρ data hint at a phase demixing effect upon increasing the ionization degree. [ABSTRACT FROM AUTHOR]

Increase crystallinity in soft domains. • New method to synthesize nanocomposite POSS-PU. • Improvement the crystallinity of soft segments by adding nanoparticles in the polyurethane matrix. • POSS nanoparticles increase the storage modulus. • Adding nanoparticles has led to improvement the recovery rate, shape recovery, explosive reversibility. Recovery rate and recovery stress are important factors that limit the use of polyurethanes, especially in the medical field. In this study, Polyhedral Oligomeric Silsesquioxane nanoparticles as chain extender have been bonded to polyurethane chains using a new synthesis method. Fourier-transform infrared spectroscopy technique to confirm synthesis reactions, Differential Scanning Calorimetry for evaluating the effect of Polyhedral Oligomeric Silsesquioxane (POSS) particles on the crystallinity of soft segments, Dynamic Mechanical Thermal Analysis for investigating mechanical properties, and Scanning Electron Microscope and X-ray diffraction have been used to evaluate the dispersion of Nanoparticles, respectively. It is observed that using Polyhedral Oligomeric Silsesquioxane solely, acts as a chain extender which does not show phase separation in synthesized nanocomposites. Using both the Polyhedral Oligomeric Silsesquioxane and 1,4-Butanediol chain extender in polyurethane synthesis reaction caused greater phase separation rather than solely 1,4-Butanediol. Finally, adding the nanoparticles caused improvement in recovery rate as well as shape recovery in the synthesized nanocomposites. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A transparent self-healing polyurethane based on disulfide bonds is reported. • The polyurethane has excellent self-healing properties and healing repeatability. • Shape memory effect acted as an auxiliary recover force for the closure of scratches. • The dynamic disulfide bonds triggered chain exchange and healed the scratches. Abstract Polymers with self-healing ability have attracted great research efforts recently. A transparent self-healing polyurethane (PU) based on disulfide bonds is reported in this work. The crystalline structures, self-healing properties of the polyurethane were investigated by differential scanning calorimetry (DSC), X-ray diffraction measurements (XRD), dynamic mechanical analysis (DMA), stress relaxation and tensile tests. The as-prepared self-healing polyurethane was transparent due to low crystallinity and exhibited excellent self-healing properties, stretchability and healing repeatability. The healing efficiency and elongation at break at a moderate healing temperature were over 90% and 800%, respectively. Meanwhile, the self-healing polyurethane exhibited an excellent healing repeatability and service reliablility. The self-healing mechanism was analyzed through surface analysis of the scratches and shape memory effect. The system was composed of a polyurethane network, which was responsible for the autonomous crack closure due to its shape memory characteristic, and an intrinsic self-healing component through dynamic disulfide bond exchange. The self-healing polyurethane might have potential applications in the fields of flexible electronics, including artificial skins, soft robotics, etc. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A multi-scale tomographic approach was used to study the structure of polymeric foams. • Gaseous phase features were examined using conventional lab-scale X-ray tomography. • Solid phase parameters were analysed by means of synchrotron X-ray tomography. • A novel analysis method to separate the solid phase in struts and walls was developed. Abstract This manuscript presents a detailed characterization of the cellular structure of two types of polymeric foams by non-destructive multi-scale X-ray computed micro-tomography. This comparative study is conducted in two different polymeric materials –rigid polyurethane foams and cross-linked low density polyethylene foams-. Based on this technique and using 3D image analysis, conventional descriptors of the foams gaseous phase (cell size distribution, mean cell size and anisotropy ratio) are characterized at a standard voxel size of 5 µm. Complementarily, 0.4 µm voxel size synchrotron X-ray tomography data sets have been used to characterize, using a new image analysis approach, features of the solid phase of the foams (fraction of mass in the struts and thickness of the different entities of the solid architecture: struts and walls). The presented methodology, based on multi-scale tomographic analysis, allows obtaining a better understanding of the connection between foaming process and cellular structure and is important to gain knowledge on the structure-properties relationships for these materials. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Isobornyl groups can be successfully incorporated into PU by thiol-ene reaction and poly-addition. • Introduction of isobornyl groups into PU markedly increases anti-bacterial adhesion performance. • The hydrophobicity of the coating films are significantly improved as a result. Abstract We report a novel environmental friendly waterborne polyurethane (WPU) coating with good anti-bacterial adhesion property and hydrophobicity. A key point of our approach is to functionize the polyurethane with isobornyl acrylate (IBA), a widely used natural material with unique chiral feature and good biocompatibility. The polyurethanes containing IBA have been synthesized by thiol-ene Michael addition reaction and poly-addition polymerization. The thiol monomer 3-mercapto-1,2-propanediol (TPG) and vinyl monomer isobornyl acrylate (IBA) have been used to obtain dihydroxy-terminated IBA (IBA(OH) 2) with triethylamine as catalyst. The structure of IBA(OH) 2 have been identified by Fourier transform infrared spectrum (FTIR), proton nuclear magnetic resonance (1H NMR), and mass spectrometry (MS). IBA(OH) 2 is then incorporated into polyurethane as a chain extender to yield a WPU with IBA side group (IWPU). The synthesized IWPU has been confirmed by FTIR, 1H NMR, X-ray photoelectron spectroscopy (XPS), and gel permeation chromatography (GPC). Thermogravimetric Analysis (TGA) measurements indicate that the thermal stability of IWPU is decreased slightly with the increasing content of IBA(OH) 2. Differential scanning calorimetry further (DSC) indicate that the T g of the IWPU coatings decreases, and the resistance to low temperature increases at a higher content of IBA(OH) 2.The introduction of IBA side groups can improve the hydrophobicity of the polyurethane, which is favorable for wide application of the coatings. Additionally, the antibacterial adhesion performance of the polyurethanes has been evaluated by plate count method and optical density (OD) test. The results demonstrate that the polyurethane coatings with 25 wt% content of IBA side groups can exhibit effective resistance to bacterial adhesion, with the inhibition ratios of 89.3% and 80.4% for E. coli and S. aureus , respectively. [ABSTRACT FROM AUTHOR]

Graphical abstract In this paper, we describe new hyperbranched polymers with combined fluorescence property, biocompatibility and shape-memory effect for the first time. Highlights • Shape-memory polyurethanes suitable for multiple applications were synthesized. • 100% shape recovery was attained on a designed object within 37 s. • The shape-memory polymers synthesized were found to be red light emitting fluorescent. • The shape-memory polymers synthesized were found to be biocompatible. Abstract Fluorescent shape-memory hyperbranched polyurethanes were prepared via A 2 + B 3 approach using stilbene based fluorescent molecules as B 3 monomers and poly(ε-caprolactone) diol and its polyurethane prepolymer as A 2 monomers. Variations in the polymerization method, reaction time, reaction temperature, A 2 :B 3 monomer ratio and end-group modification resulted polymers with molecular weight (M w) in the range of 3.48 × 104–6.8 × 105 g mol−1 as determined by SEC-MALS technique. Polymers prepared using hydroxyl-terminated polyurethane prepolymer were characterized by TGA, DSC, WAXD, shape-memory test, UV–visible and fluorescence spectroscopic techniques. The crystallinity of polymers determined from WAXD data were found consistent with that determined from DSC data. Among the considerable number of polymers synthesized, the polymers end-capped with polyethylene glycol monomethyl ether exhibited film formation, thus these polymers were tested for their shape-memory effect and fluorescence properties. It was found that these polymers attained 100% shape recovery within 12 s at 50 °C or within 4 s at 60 °C. Absorption and fluorescence spectroscopic data of polymer film confirmed that these polymers were red-light emitting fluorescent. The adhesion and proliferation data obtained with neuroblastoma cell validated the biocompatibility of these polymers. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Non isocyanate polyurethanes (NIPUs) were prepared using a new approach. • Monomers with methyl carbamate and methyl carbonate end-groups were prepared. • Cross metathesis polymerization was performed on the prepared monomers. • K 2 CO 3 was efficient to catalyze the reaction. • Cross metathesis reaction afforded NIPUs with good thermal properties. Abstract AA-BB and AB-type Non-Isocyanate Polyurethanes (NIPUs) were synthesized through a cross metathesis polymerization between methyl carbamate and methyl carbonate groups within AA-BB and AB monomers. These monomers were prepared by reaction of diamines, diols or amino-alcohols with an excess of dimethylcarbonate (DMC), using 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as catalyst. Due to a slight chain extension, dimethyl dicarbonate monomers as well as AB-type monomers contained few carbonate groups, which were present within the final NIPUs. The polymerization was performed in bulk at 200 °C, using K 2 CO 3 as catalyst. Except for AB-type monomers obtained from amino-alcohols with 3 and 4 methylene groups, the polymerization was successful leading selectively to the expected NIPUs. These materials exhibited good thermal properties with Tg ranging from −35 to 10 °C, T m ranging from 96 to 256 °C and degradation temperature above 200 °C. The polyurethane properties were generally intermediate comparing to those of polyurea and polycarbonate analogues prepared in the same conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • The SMPU had outstanding room temperature self-healing ability. • Molecular simulations were used to elucidate the self-healing mechanism further. • Its excellent mechanical properties and recyclability make it highly valuable for a range of applications. • The leather coated with SMPU showed remarkable and durable wear resistance. Achieving severe damage restoration and the ideal combination of good mechanical properties and healing efficiency are two significant challenges for self-healing materials. In this study, a series of shape-memory, self-healing aqueous polyurethane (SMPU) were synthesized based on the molecular self-assembly design of 5-(2-hydroxyethyl)-6-methyl-2-aminuracil (HMA), 4-aminopyridine (4-APD) and polycaprolactone diol (PCL) moieties. The effects of HMA and 4-APD on mechanical properties, self-healing properties, and shape memory properties of SMPU were investigated. The dynamic crosslinking network generated by quadruple hydrogen bonds and multiple coordination bonds not only consumed strain energy but also promoted rapid re-formation after fracture, resulting in superior self-healing ability (healing efficiency 96.3%), excellent mechanical properties (tensile strength 39.1 MPa and elongation at break 908%) and recyclable capabilities of SMPU. Meanwhile, the SMPU showed a noteworthy shape memory effect; its shape fixation rate and recovery rate could reach 99% and 98%, respectively. The temperature and time dependence of the self-healing process were studied by molecular dynamics (MD), and the self-healing mechanism was clarified further. When SMPU was used for leather finishing, the finished and self-healing samples exhibited excellent wear resistance (wear rating: 4 ∼ 5). These advantageous properties endow SMPU with great potential applied value in leather and other regions. [ABSTRACT FROM AUTHOR]

In our research, a type of polyurethane acrylate is successfully synthesized and then compounded with epoxy acrylate and isobornyl acrylate as well as radical photoinitiator to get photopolymer. Afterwards, the photopolymer is applied through stereolithography 3D printing to fabricate shape memory polymers. The photopolymer is proved to have high UV-curing activity and the printing accuracy is high. Fold-deploy test and shape memory cycles measurements prove the excellent shape memory performance of the printed objects, including high shape recovery rate, shape fixity and recovery and excellent endurance. The shape fixity and recovery ratios are 96.77 ± 0.06% and 100.00 ± 0.08%, respectively. Tensile test at 70 °C shows that the recovery stress of printed objects can reach as high as 6.4 MPa. Mechanical test shows the printed objects have high strength and good toughness. With excellent shape memory performance, good mechanical properties and high printing accuracy, such material has great potential applications in many fields. [ABSTRACT FROM AUTHOR]

Polyurethanes STMPU and HTMPU containing AIE fluorogens in the soft segments and hard segments, respectively, have been synthesized and characterized. Both two resulting polyurethane solutions exhibited an aggregation-enhanced emission (AEE) feature. Then two kinds of polyurethane films were prepared and their multi-stimuli-responsive properties were explored. Interestingly, the fluorescence emission of two polyurethane films were decreased in high temperature, and polyurethanes with different structures have different temperature-dependent fluorescent behaviors. Meanwhile, weak emission was obtained when acetone was dripped onto the two polyurethane films. Moreover, the fluorescence of the polyurethane STMPU film was greatly enhanced with the increase of tensile stress (at ε < 0.3), suggesting its potential application in multifunctional fluorescent probes. [ABSTRACT FROM AUTHOR]

This work globally redesigns the conventional approach in obtaining polyurethane foams (PUF), from sorbitol. Fully biobased polyester polyols were synthesized from sorbitol, adipic or succinic acid and different renewable C2 to C12 diols as the first step towards the elaboration of PUF. Sorbitol-based polyester polyols were synthesized through a two-step esterification without catalyst. The absence of a catalyst limits some side reactions and focuses the reaction on the primary hydroxyl groups of the sorbitol, to obtain the linear molecular structure. The global yields of the corresponding esterifications were above 80%. Hydroxyl values and acid values of the corresponding linear biobased polyester polyols ranged from 440 to 683 mg KOH/g, and from 11 to 49 mg KOH/g, respectively. Acid values were decreased below 10 mg KOH/g by neutralization. PUF were prepared with polyols blends containing this biobased polyester polyol (up to 75 wt%) and a conventional fossil based polyol e.g., oxypropylated glycerol, which present a high fossil content. The final biobased content of the PUF ranged up to 28 wt% in contrast to 9 wt% for the reference. Then the addition of neat glycerol to the polyol blend increased the final biobased contents of the PUF foams up to 31 wt%. In contrast with the traditional approach consisting of modifying the catalyst content, the activation of the reactive foaming process was improved through initial polyols blends. The final biobased PUF foaming kinetic was similar to that of the polyether polyol, used as a reference. Finally, the effects of chemical and physical blowing agents (water vs. isopentane) were compared on the foaming rate and foam structure. The use of chemical blowing agent efficiently decreased the foam gel time of 33% and increased the foaming rate of 1 mm/s with biobased systems. Besides, the polyols architecture has a strong influence on the foam tack free time which varied from 50 to 235 s for the studied PUF. [ABSTRACT FROM AUTHOR]

The present work reports synthesis and development of zwitterionic tri-block copolymer-polyurethane (ZTC-PU) coatings which are thermally stable and have hydrophobic properties which can be used for marine applications. The zwitterionic tri-block copolymer (ZTC) (poly(sulfobetaine methacrylate) - polydimethylsiloxane - poly(sulfobetaine methacrylate), polySBMA-block-PDMS-block-polySBMA) was synthesized by ATRP (atom transfer radical polymerization) method. Apart from this, the facile synthesis of silane functionalized acrylic polyol was formulated with 4,4′- Methylene dicyclohexyl diisocyanate (H12 MDI) for the development of polyurethane (PU) coatings. Different weight ratios of ZTC was incorporated in PU to obtain a zwitterionic tri-block copolymer-polyurethane (ZTC-PU) coatings. The ZTC-PU coating exhibit good thermal stability and hydrophobic property. The coating showed excellent non-specific marine bacterial inhibition property along with good stability against gram positive Staphylococcus aureus ( S. aureus ) and gram negative Escherichia coli ( E. coli ) , Pseudomonas aeruginosa ( P. aeruginosa ) microbial strains. This design method reveals the development of zwitterionic-polyurethane coatings with higher amount of zwitterionic moiety in the coating system, that will be efficient and eco-friendly technology for marine bio-fouling application. [ABSTRACT FROM AUTHOR]

We have first confirmed that an organic acid, diphenyl phosphate (DPP) is effective in a sequential process of ring-opening polymerization (ROP) of a cyclic carbonate and polyaddition with a diisocyanate. More potent triflic acid (TfOH) exhibited higher catalytic activities for both ROP and polyaddition than DPP and pairs of thiourea and basic catalysts such as cyclic amidines and sparteine. However, DPP-catalyzed ROP was more manageable than that using TfOH regarding control over the molar-mass dispersity of the resultant polycarbonates that matters to the final polyurethanes. As a consequence of DPP-catalyzed one-pot synthesis of poly(carbonate-urethane)s, we have obtained segmented polyurethanes comprising a poly(trimethylene carbonate) analog with ether side chains as a soft segment and hexamethylene diisocyanate as a hard segment. Although the whole reaction took a few days, high molecular weight over 50 k was achieved for the resultant polyurethanes whose texture suggested improved physical properties. Nevertheless, the polyuretahnes maintained low platelet adhesion properties. This antithrombotic polyurethane became more promising as a candidate base material for resorbable artificial blood vessels. Furthermore, this sequential synthesis by single organocatalysts enables the efficient production of functionalized poly(carbonate-urethane)s. [ABSTRACT FROM AUTHOR]

[Display omitted] • Preparation at room temperature of microcellular poly(β-hydroxythioether) foams without use of external blowing agents. • The polymer is obtained by a simple S-alkylation reaction of bis(cyclic carbonate)s monomers and trithiol and tetrathiol. • The thiol compounds act simultaneously as cross-linking and foaming agents during the reaction. • The control of flexibility and density of the foams could be achieved by the nature and ratio of the tiol (tetra- or trithiol) used in the polymerization process. A novel strategy was developed to prepare a self-blowing poly(β-hydroxythioether) foam at room temperature by S-alkylation of 5-membered bis-cyclic carbonate using multifunctional thiol monomers. Two different thiol compounds, trimethylolpropane tris(3-mercaptopropionate) and pentaerythritol tetrakis(3-mercaptopropanoic acid) were used for the decarboxylative s-alkylation reaction. The thiol compounds simultaneously act as crosslinking agents and generate carbon dioxide during the decarboxylative s-alkylation reaction. This enables foam preparation without an external blowing agent. The use of tetrathiol monomer improves thermal stability, provides flexibility to the foams, and induces an increase in the glass transition temperature (Tg) due to a higher degree of cross-linking. The apparent density of the foams decreases with the increase of the tetrathiol ratio. This novel solvent-free approach paves the way to design sustainable foams with modular properties using accessible components and additives, as well as provides an alternative to non-isocyanate polyurethane foams. [ABSTRACT FROM AUTHOR]

[Display omitted] The valorization of lignin in polyurethane products allows biorefineries and paper industries to use this biomass with some added value and not waste most of it in combustion to generate energy. Lignin is known as the second most abundant natural polymer in the world. It comprises a complex structure formed by covalent bonds between phenylpropanoid alcohols, making its composition heterogeneous. In recent decades, lignin has been exploited as a raw material in the synthesis of polyurethanes to replace petrochemical derivatives. Despite its promising characteristics in polyurethane products, lignin has limitations in its use due to its highly complex and cross-linked molecular structure. To overcome this challenge, methods have been developed to make lignin more reactive, facilitating its use in various polymeric processes. Among the methods is chemical modification and fragmentation of lignin. Although research has advanced concerning the depolymerization of lignin through chemical catalysis and enzymatic catalysis synthesis, research only focuses on the process of functionalizing lignin for its application in various areas, however, these explored methods are considered as pretreatment of biomass, adding another step in the polyurethane synthesis. Scientific efforts should also be directed to studies on the production of lignopolyols derived from enzymatic catalysis to produce polyurethanes. Thus, this review addresses conventional methods used in the chemical modification of lignin and ways of application, including polyurethane products that can be developed based on lignin, briefly addresses studies related to enzyme vs. lignin, and points out a gap that exists in the literature on enzymatic catalysis in the production of lignopolyols applicable to PUs. [ABSTRACT FROM AUTHOR]

Polymer blending techniques can address the disadvantages of polyolefin-based polymers by creating a mixture of polymers with different characteristics. One of the polyolefin-based polymers is polypropylene (PP), which has good mechanical strength and machinability, but its weakness is impact resistance at low-temperature. In contrast, polyurethane (PU) has excellent mechanical and thermal properties. However, blending PP and PU has been limited because PP is a hydrophobic polymer, and PU is a hydrophilic polymer. In this study, we used gamma-irradiation (doses of 25 and 50 kGy) to graft styrene onto PU to change its hydrophilicity into hydrophobicity, and we developed PP blends with styrene grafted PU (PP/SPU) blends. With increasing styrene content and radiation dose, the surface morphologies (determined by using a field emission scanning electron microscope (FE-SEM) were smoother than PP blended unmodified PU owing to the styrene that was successfully grafted onto the PU and blended with PP. The mechanical properties of the PP/SPU blends were confirmed using a universal testing machine (UTM). Whereas the elongation at break of the PP was 518%, the low-temperature resistance (−20 °C) of the PP was decreased to 304%. However, the elongation at the break of the PP/SPU blends was almost unchanged in terms of both the mechanical property (594%) and low-temperature resistance (607%). After holding in oven at 150 °C for 1 h, the thermal stability of PP/SPU increased by more than quadrupled, compared to PP. In addition, the permittivity of PP/SPU increased with radiation dose compared to PP. Energy dispersive X-ray spectroscopy (EDS), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and differential scanning calorimetry (DSC) were also used to evaluate the blended polymers. Therefore, this study confirmed the possibility of developing highly functional polymers using radiation-based techniques. [ABSTRACT FROM AUTHOR]

The facile chemical fixation of 18 wt.% carbon dioxide by catalytic carbonation of sorbitol glycidyl ether, monitored by means of NMR and FTIR spectroscopy, affords sorbitol-based cyclic ether carbonate (SEC) as versatile intermediate for producing renewable non-isocyanate polyhydroxydroxyurethane (NIPU) materials. In sharp contrast to the solid, crystalline and highly insoluble pure sorbitol tricarbonate (STC), melting above 200 °C close to its decomposition temperature, SEC is liquid at room temperature and fully miscible with a wide variety of polyfunctional amine curing agents. Despite high SEC carbonate functionality (4.2 mol/kg), both gel time and pot-life time measurements confirm easy processing by curing SEC with polyfunctional aliphatic amines to produce new families of sorbitol-based NIPU materials. Particularly, blends combining flexible long-chain diamines such as dimer fatty acid based diamine (Priamine™ 1074) or polyether triamine (Jeffamine™ T403), respectively, with rigid short-chain diamines such as 1,6-hexamethylene diamine (HMDA), 1,12-dodecyl diamine (DDA), 2,2,4-trimethylhexamethylene diamine (TMHMDA) and isophorone diamine (IPDA), enable the simultaneous incorporation of soft and hard segments into NIPU networks. Moreover, miscible blends of SEC with STC remain liquid up to high STC content. Unparalleled by conventional bio-based NIPU chemistry, the curing of SEC or miscible SEC/STC blends, respectively, with IPDA yields sorbitol-based NIPU thermosets exhibiting significantly improved thermal and mechanical properties, as reflected by high glass transition temperatures surpassing 180 °C and Young moduli exceeding 4000 MPa. [ABSTRACT FROM AUTHOR]

The synthesis of novel polyurethanes is a subject of increasing interest, especially those that involve biologically active molecules. Generally, the reports on the synthesis of segmented polyurethanes using modified amino acids as chain extenders assume that the reaction occurs due to functionalities (OH and NH 2 ) of the last compounds. However, few works really prove the reaction takes place with unmodified amino acids. In this work, spectroscopic techniques such as 1 H, 13 C, and 1 H-1H COSY NMR and FTIR were used to chemical characterization of poly(urea-amide) urethanes synthesized from polycaprolactone diol (PCL diol 530), 4,4′-methylene-bis(cyclohexyl isocyanate) (H 12 MDI), and amino acids such as l -arginine, glycine or l -aspartic acid as chain extenders. In addition, model compounds (without PCL diol) were analyzed to confirm reaction of amino acids via urea and amide formation. Additionally, the polymers exhibited different physicochemical and mechanical properties depending on the chain extender used. These results suggest that unmodified amino acids can be used as chain extenders in the synthesis of poly(amide-urea) urethanes for biomedical applications. [ABSTRACT FROM AUTHOR]

Waste polyethylene terephthalate (PET) is depolymerized through glycolysis and the glycolyzed product, bis (2-hydroxyethylene) terephthalate (BHET) is utilized in the synthesis of polyurethane as diol. Polyurethane (PU) is incorporated in a core- shell nanoparticle formulation along with alginate (ALG) and chitosan (CS) to develop an efficient oral insulin delivery vehicle. Fourier transform infrared (FT-IR) spectrums of the polyurethane-alginate/chitosan (PU-ALG/CS) nanoparticles confirm the presence of all elements distinctly. Nanoparticles of average particle size 90–110 nm are clearly visible from the images of scanning electron microscope (SEM) and transmission electron microscope (TEM). Unique characteristics of insulin loaded PU-ALG/CS nanoparticles are noticed in both in vitro and in vivo studies. More than 90% insulin encapsulation efficiency, sustained swelling, controlled insulin release from mucoadhesive nanoparticle formulation are the major causes of long term hypoglycaemic effects in diabetic mice and improved insulin bioavailability (10.36%). PU-ALG/CS nanoparticles are also found to be safe, according to the acute toxicity studies. [ABSTRACT FROM AUTHOR]

The surface state is a major parameter for the biocompatibility of medical devices. During storage, the blooming of additives may occur on the surface of polymers and modify their properties. In this study, the impact of sterilizing and oxidation treatments on blooming was studied. The study was realized on polyurethane used in the fabrication of catheters on which the blooming of antioxidant crystals has been previously observed. Sterilization by ionizing radiations (beta, gamma) was performed on this material and samples were submitted to different kinds of oxidation process (UV, H 2 O 2 and macrophages action). Surface evolution was investigated using AFM microscopy, FTIR-ATR and SEM. [ABSTRACT FROM AUTHOR]

Catechin (Cat) was added into polyurethane (PU) based on a tri-block copolymer of poly( l -lactic acid) and poly(ε-caprolactone) (PLLA- b -PCL- b -PLLA) to improve the thermal stability of the final PU composite materials. The morphological, structural, mechanical and thermal properties of PU-Cat composites loaded with 1 wt%, 3 wt% and 5 wt% of Cat were investigated and designed as PU-Cat1, PU-Cat3 and PU-Cat5, respectively. Homogeneous films were obtained after the solvent casting process, but the higher amount of 5 wt% used in this work could not be successfully dispersed and produced some structural defects as were observed by scanning electron microscopy. Well dispersed Cat in PU-Cat1 and PU-Cat3 not only substantially improved the thermal stability due to the Cat antioxidant effect, but also allowed the crystallization of PCL and PLLA blocks in the final PU-Cat composites. Additionally, PU-Cat composite materials showed excellent stretchability for film production. [ABSTRACT FROM AUTHOR]

Owing to their outstanding variety of properties, nanoparticles attracted considerable interest for developing a new age of novel polymer nanocomposites and adhesives. Among them, inorganic nanotubes (INTs) of tungsten disulfide (WS 2 ) and carbon nanotubes (CNTs) have been identified as unique candidates for many industrial applications by virtue of their superior mechanical, thermal and tribological properties. In this work, a comparative study between INT-WS 2 and multi-walled carbon nanotubes (MWCNTs) regarding the properties of structural polyurethane (PU) adhesives is presented. Specifically, we evaluate the thermomechanical properties, chemical and micro-phase structure, bonded joints performance in lap shear and peel modes, and fracture mechanisms, with aiming to highlight some of the differences between these nanotubes. The added content spanned over the range of 0.3, 0.6, 0.9 and 1.2 wt% of INT-WS 2 , while CNTs are incorporated at the same volumetric fractions (e.g., 0.1, 0.2, 0.3 and 0.4 wt%). According to the results of the tests, in all measured aspects, INT-WS 2 outperformed the carbon counterparts. With regards to the thermomechanical attributes, the hard segment Tg of the PU increased by 14 °C at 0.6 wt% INTs, whereas CNTs recorded only modest improvement of 8 °C at the nanocomposite loaded with 0.4 wt%. The structural bonding performance indicates an improvement of 117% and 38% in the shear and peel strengths at 0.9 and 1.2 wt% INTs, respectively, while CNTs show moderate changes. Interestingly, the changes are also reflected by the interplay between the hard and soft segments of the PU, and different fracture mechanisms operating within the nanocomposites. At any rate, the combined attributes of >20 MPa in the shear strength and approximately 2 N/mm in (average) peel strength, targets the PU/INT nanoadhesives as promising alternative for conventional epoxy systems which has similar shear strength with inferior peel strength. [ABSTRACT FROM AUTHOR]

This paper describes the use of microwave radiation in the synthesis of urethane prepolymers in bulk (without solvent). The prepolymers were synthesized using 1,6-hexamethylene diisocyanate (HDI) and poly (ε-caprolactone) diol (PCL) at a molar ratio of 4:1. The reaction was carried out without a catalyst in the reactor with a conventional heating system (oil bath) or in the microwave reactor (MW Reactor NOVA 09) at temperatures of 60, 80 and 100 °C. The progress of the reaction was monitored based on the degree of HDI and PCL conversion, as assessed by acidimetric titration of non-bonded isocyanate groups (0–120 min). The chemical structure of the resulting products was determined via Fourier Transform Infrared Spectroscopy. Size exclusion chromatography (GPC) was applied to determine the molecular weight distribution of products at different time points of prepolymer synthesis. The obtained results indicate that the use of microwave radiation as a heat source during prepolymer synthesis accelerates the reaction in the temperature range from 60 to 80 °C. This finding allows a significant reduction in energy required for heating the reaction mixture. The acceleration of prepolymer synthesis by the application of microwave radiation as a heat source also allows for the elimination of catalysts from the system. The aforementioned catalysts are necessary to perform the prepolymer synthesis with the use of aliphatic diisocyanates and polyols, particularly at temperatures below 100 °C. In the case of prepolymers that are further used in the synthesis of biomedical polyurethanes, the catalyst elimination is especially advantageous as the presence of residual catalyst may significantly influence the final material’s biocompatibility and disturb host cell viability. [ABSTRACT FROM AUTHOR]

Sustainable routes for the synthesis of polyurethanes with industrial applications are discussed in this article. Polyurethane is currently one of the most commonly used polymers worldwide for various applications such as rigid and flexible foams, coatings, elastomers, adhesives and sealants. However, isocyanate precursors are very harmful at each stages of the life cycle of the polymers. Hence, new synthesis routes for isocyanate-free polyurethanes are reported in literature, but most of them suffer from significant lacks that prevent any industrial application. This feature article focuses on the new challenges and new opportunities of these routes. A first part is dedicated to the market, the manufacture and the hazards of polyurethanes. In a second part, this article deals with the synthesis routes leading to non-isocyanate polyurethane. Hence, the advantages and limits of these routes are reported and discussed. Finally the outlooks for a future and industrial use of non-isocyanate polyurethane in industry are examined. [ABSTRACT FROM AUTHOR]

The aim of the current work was to prepare and characterize a cellulose nanocrystal reinforced semi-interpenetrated network (SIPN) derived from polylactic acid (PLA) and polyurethane (PU) polymers. SIPN films were prepared using solvent casting from 1,4-dioxane solution. The morphology, mechanical and thermal properties of the neat SIPN and its nanocomposite were characterized. A novel dispersion method was used, for the first time, to disperse the CNCs into the polyol. This method led to well dispersed CNCs in the SIPN, and at 1 wt% CNC concentration, the elastic modulus of the nanocomposite was improved by 54% over an unreinforced SIPN. Additionally, the results indicated that the toughness of PLA, which is the main polymer phase, was improved. However, in the nanocomposite, CNCs formed a strong network and reinforced the PU phase, which resulted in a lower toughness of the final material. The storage modulus of the SIPN nanocomposite was higher than that of the neat PLA at temperatures higher than 55 °C up to 100 °C. This increase in thermomechanical properties indicates that the reinforced PU network in the PLA matrix can enhance the thermal behavior of material. [ABSTRACT FROM AUTHOR]

A series of poly(hydroxyurethane) (PHU) materials were synthesized by step growth polymerization of cyclic carbonates and diamines. Trimethylolpropane tris-carbonate and various poly(propylene oxide) bis-carbonates were copolymerized with EDR-148 or 1,3-cyclohexanebis(methylamine) (CBMA). Thermal, mechanical and thermo-mechanical properties of PHU materials were characterized by DSC, TGA, durometer, dynamometer and DMA. Moreover, for the first time, we report adhesive properties of PHU synthesized without isocyanate on wood, aluminum and glass supports. All these properties were compared to reference polyurethane materials, synthesized from poly(propylene oxide) triol polymerized with hexamethylenediisocyante (HDI) or 1,3-bis(isocyanatomethyl)cyclohexane (CBMI), in order to compare the materials properties of similar chemical structure. PHUs exhibit outstanding adhesion properties due to the presence of hydroxyl groups hanging off the main polycarbonate chain. [ABSTRACT FROM AUTHOR]

Non-isocyanate thermoplastic polyhydroxyurethane (PHU) elastomers were synthesized from cyclic carbonate aminolysis using polytetramethylene oxide (PTMO) as soft segment and divinylbenzene dicyclocarbonate and three diamine chain extenders as hard segment with a range of hard-segment content. Characterization was done via Fourier transform infrared spectroscopy, small-angle X-ray scattering (SAXS), uniaxial tensile testing, and dynamic mechanical analysis (DMA). SAXS reveals that these PHUs possess nanophase-separated morphology with 10–20 nm interdomain spacings. These PHUs display elastomeric response and tunable tensile properties with Young’s modulus ranging from 27 to 200 MPa, tensile strength from 0.3 to 9.7 MPa and elongation at break ranging up to greater than 2000%. DMA reveals that nanophase separation in these PHUs is accompanied by broad interphases having a wide range of local composition; this nanophase separation differs significantly from that manifested by thermoplastic polyurethane elastomer (TPU) due to hydrogen bonding of hydroxyl groups in the hard segments to the PTMO soft segment. These PHUs show very good damping performance with tan δ ⩾ 0.30 over broad temperature ranges (⩾60 °C), which are tunable through simple variation of hard-segment content and chain extender structures. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new aziridine-based multicomponent polymerization protocol was developed. • Novel poly(sulfonamide urethane)s were synthesized under metal-free conditions. • The linear polymeric structure was well controlled. • Optically active polymers were prepared from chiral aziridines. • The thermal properties were provided. We report an organocatalytic aziridine-based multicomponent polymerization approach toward poly(sulfonamide urethane)s. The polymerization was carried out using bis(N -sulfonyl aziridine)s, diols, and tosyl isocyanate as the monomers and MTBD as the organocatalyst. Excellent yields (81–98%) were obtained for the desired step-growth polymerized products. The linear polymer structure was achieved, with no branching and cross-linking. Optically active poly(sulfonamide urethane)s were synthesized from chiral bis(N -sulfonyl aziridine) monomers. Thermal analysis of the poly(sulfonamide urethane)s revealed a decomposition temperature (T d,5%) up to 284.4 °C at 5% weight loss. DSC analysis indicated that the glass transition temperature (T g) ranged from 64.9 to 99.5 °C. Such results are anticipated to accelerate the development of the aziridine-based synthetic approach toward functional polymeric materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • A one-shot two-step method using organic DBU as catalyst for both ring-opening polymerization (ROP) and polyaddition rection was applied to prepare new poly(ether-ester-urethane) (PEEU). • Amorphous poly(1,5-dioxepan-2-one) (PDXO) diols constituted with ether and ester linkages in one repeating unit was used as soft segments. • Hydrophilic ether groups and amorphous structure of PDXO could accelerate the degradation of the new PEEU. Development of controllable, versatile and robust degradable polyurethane (PU) is of continued attraction regarding its wide application in the field of biology and medicine. Herein, new degradable poly(ether-ester-urethane) (PEEU) with amorphous and hydrophilic poly(1,5-dioxepan-2-one) (PDXO) diols as the soft segments and 4,4-diphenylmethane diisocyanate (MDI) and butane-1,4-diols (BDO) as the hard segments was synthesized by the one-shot two -step method in a controllable manner. The degradation behavior of PEEU with various compositions in vitro was investigated by observing the changes of weight loss, molecular weight and surface morphology during the 140 days of degradation. The weight loss and degradation rate of PEEU were faster than that of PU with semi-crystallized poly(ε -caprolactone) diols as soft segments and a surface to bulk degradation process was observed by scanning electron microscopy (SEM). In addition, the weight loss decreased by increasing the hard segments composition and the weight loss was mainly from the hydrolysis of ester linkages. [ABSTRACT FROM AUTHOR]

A polyether based thermoplastic polyurethane (TPU) containing 43 wt.% hard domains is aged in air at 150 °C for 15 and 36 days, respectively. Straining of the samples (0 d, 15 d, 36 d) is monitored by small-angle X-ray scattering (SAXS). Visual inspection of the chord distribution functions (CDFs) guides to a model for the fitting of the longitudinal projection of the fiber scattering. This model comprises two components: isolated hard domains (solos) and hard domains which are arranged with respect to a next neighbor (duos). Aging increases the average size of the hard domains (HD) (0 d:5, 15 d:8, 36 d:7 nm) and the average distance between them (0 d:3, 15 d:6, 36 d:9 nm). It decreases the volume fraction of HD considerably. The probable mechanism is selective degradation of the smaller hard domains. With increasing strain the relative loss of HD is the same for all samples. Aging softens the HDs. Softened HDs lengthen when the sample is stretched. They are destroyed before the rigid ones. HD-lengthening is identical for sample 15 d and 36 d. Only with the aged materials small strain causes HDs to migrate from the random to the arranged component – and back at higher strain. Sample 36 d breaks at strain 1.5, whereas sample 15 d resists. Here the soft-domain height doubles suddenly at strain 1.2. The indicated mechanism is disruption of each second HD. [ABSTRACT FROM AUTHOR]

A new coumarin diol was designed and used as initiator for the ring opening polymerization of ε-caprolactone. A photo-reactive polyurethane based on the resulting polycaprolactone diol with pendant coumarin moieties was synthesized. Photo-dimerization/photocleavage reactions were studied by UV and Raman. The linear non-irradiated soft polyurethane transformed into a tough elastomeric crosslinked material. DQ-NMR measurements showed that conversion of the photo-reaction was not directly related to relative amount of crosslinking but provided complementary information. Crosslinking reduced the crystallinity of the polycaprolactone segments and the melting point of the crystals. [ABSTRACT FROM AUTHOR]