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In recent years, global warming has been increasing, while conventional cooling devices remain inefficient and can emit greenhouse gases. The research and development of passive daytime radiative cooling (PDRC) are of utmost importance. Herein, a novel technique called water‐assisted thermally induced phase separation (WA‐TIPS) is employed to prepare thermoplastic polyurethane (TPU) foams with a hierarchical micro/nanostructure. By adding 2 mL of deionized water, the TPU foam achieves a solar reflectance of up to 95.5% and can provide a cooling effect of up to 7 °C during daytime, showcasing its significant potential for PDRC applications. Furthermore, leveraging the WA‐TIPS technique, the cooling performance of a composite foam consisting of TPU and SiO2 nanoparticles is investigated. Remarkably, it is discovered that incorporating just 0.1 g of SiO2 nanoparticles allows the composite foam to achieve daytime cooling of up to 15 °C. In this work, not only a novel approach for constructing micro/nanostructures is introduced but also a theoretical and experimental framework for advancing the development of polymer or polymer composite PDRC devices is established. [ABSTRACT FROM AUTHOR]

A series of CO2-based thermoplastic polyurethanes (TPUs) were prepared using CO2-based poly(polycarbonate) diol (PPCDL), 4,4′-methylenebis (cyclohexyl isocyanate) (HMDI), and polypropylene glycol (PPG and 1,4-butanediol (BDO) as the raw materials. The mechanical, thermal, optical, and barrier properties shape memory behaviors, while biocompatibility and degradation behaviors of the CO2-based TPUs are also systematically investigated. All the synthesized TPUs are highly transparent amorphous polymers, with one glass transition temperature at ~15–45 °C varying with hard segment content and soft segment composition. When PPG is incorporated into the soft segments, the resultant TPUs exhibit excellent self-healing and shape memory performances with the average shape fixity ratio and shape recovery ratio as high as 98.9% and 88.3%, respectively. Furthermore, the CO2-based TPUs also show superior water vapor permeability resistance, good biocompatibility, and good biodegradation properties, demonstrating their pretty competitive potential in the polyurethane industry applications. [ABSTRACT FROM AUTHOR]

Metal‐Organic Framework (MOF) materials can be used as flame‐retardants and smoke suppressants for polymers. As a MOF material, UIO‐66(Zr) possesses higher thermal stability and controllable pore size. In this paper, UIO‐66(Zr), NH2‐UIO‐66(Zr), and SiO2, MWCNT, and GO functionalized NH2‐UIO‐66(Zr) was fabricated to improve the flame retardant and smoke suppression performance of thermoplastic polyurethanes (TPU). The experimental results show that compared with neat TPU (LOI value 19.1 %), 2 % usage of UIO‐66(Zr) and NH2‐UIO‐66(Zr) can endow TPU with 26 % LOI value and vertical combustion rating of V‐1. Moreover, SiO2, MWCNT, and GO functionalized NH2‐UIO‐66(Zr) provide TPU with above 27.8 % LOI value and vertical combustion rating of V‐0. Meanwhile, the CCT results showed that the peak heat release rate and total heat release of TPU‐U5 (added 2 % GO‐modified NH2‐UIO‐66(Zr)) are 299.52 Kw ⋅ m−2 and 68.21 MJ m−2, much lower than that of neat TPU, which are 1180.05 Kw ⋅ m−2and 104.87 MJ m−2, respectively. The TGA, char residue EDS and XRD analysis show that SiO2, MWCNT, and GO functionalized NH2‐UIO‐66(Zr) could generate zirconium metal oxide during the combustion process, which acts as a physical barrier to prevent the TPU matrix by promoting the generation of carbonization layer. The zirconium metal oxide and carbonization layer also can confine flammable gases, which can delay the ignition time and hinder the overflow of gas. In addition, NH2‐UIO‐66(Zr) could generate non‐flammable N2 diluting the concentration of flammable gases. The mechanical properties of TPU composites can maintain more than 87 % of the neat TPU after the addition of 2 % SiO2, MWCNT, and GO functionalized NH2‐UIO‐66(Zr). These results indicate that functionalized Zr‐MOFs composites could act as excellent flame‐retardants in TPU. [ABSTRACT FROM AUTHOR]

The objective of the study is preparation of shape memory blend of polycarbonate (PC) and thermoplastic polyurethane (TPU). Polycarbonate is blended with three types of TPUs and subsequently mechanical, thermal, morphological, and shape memory properties of the PC/TPU blends are studied. When TPU content in the blend is higher than 40% (by weight), the glass transition temperature related to PC is not shown in the differential scanning calorimetry thermogram, indicating loss of PC properties. The 60/40 optimized blend of PC/TPUs exhibits maximum increment of about 1100% in elongation and 43% decrement in tensile strength. The shape recovery of the optimized blend obtained by addition of 40% (by weight) of TPUs in PC polymer is found to be 65% and shape fixity is 97%. These results suggest that the blend of PC/TPU may be utilized for various applications where shape memory property is required including strategic applications. [ABSTRACT FROM AUTHOR]

In this manuscript, the UiO-66-NH2(Zr) (MOFs) was adopted to modify ammonium polyphosphate (APP), and the novel synergistic integrated flame retardant system (APP@MOFs) was formed. The flame retardants were incorporated to the thermoplastic polyurethanes (TPU) matrix, and the effects of APP@MOFs on reducing flammability of thermoplastic polyurethanes were compared and investigated. The results show that the flame retardant and smoke suppression performances of TPU/APP@MOFs composites are improved significantly. The pHRR, THR, SPR, TSP, YCO, and YCO2 of TPU/APP@MOFs composites decreased by 75.76%, 86.19%, 69.74%, 86.34%, 57.14%, and 76.37% in comparison with pure TPU. Furthermore, the char residues increased from 0.11 (pure TPU) to 32.3% (TPU/APP@MOFs composites). Generally, the APP@MOFs have great effect on improving the flame retardant and smoke suppression performances of TPU due to the catalytic carbonization and dilution effects of APP, the synergistic and catalysis effects of MOFs. Through the char structure analysis, the mechanism of the TPU/APP@MOFs composites during the combustion processes was also investigated and proposed. [ABSTRACT FROM AUTHOR]

A kind of rare earth flame retardant, two-dimensional lamellar compounds (MXene) loading with cerium phosphate nanorod, MXene@CePO4 (CMX) was prepared by hydrothermal and electrostatic adsorption methods. It was then applied in thermoplastic polyurethane (TPU). With the 3 wt% addition of CMX improving the mass rate of residual char from 4.42 wt% to 11.33 wt% compared to pristine TPU, there were reductions of 53.8%, 12.3%, and 24.7% in peak heat release rate (pHRR), total heat release (THR), and smoke density maximum (Ds max), respectively. Moreover, the TPU/CMX composites were shown to have superior mechanical properties compared with pristine TPU. For TPU/CMX-3.0, there was a visible improvement in tensile strength (TS) and elongation at break (EB) of 12.5% and 54.1% respectively, compared to pure TPU. The analysis of the flame retardancy mechanism of TPU/CMX shows that CMX plays an effective role in quenching free radicals in the gas phase and promotes char formation of TPU in the condense phase. Therefore, this paper offers a new solution for designing multifunctional rare earth flame retardants that are applied in TPU, thereby extending its application in industries and daily life. [ABSTRACT FROM AUTHOR]

Objective: This systematic review examines the efficacy and biocompatibility of orthodontic clear aligner tooth aligners constructed from polyethylene terephthalate glycol (PeT-G), polypropylene (PP), polycarbonate (PC), thermoplastic polyurethanes (TPUs), and ethylene-vinyl acetate (EVA). Materials and Methods: To find relevant papers published through September 2021, PubMed was searched extensively. Randomized clinical trials (RCTs) and observational studies assessing the effectiveness and biocompatibility of the aligner materials were included. Data were extracted independently, and the quality of included research was appraised using relevant procedures. The research variability necessitated a narrative synthesis. Results: Five studies were included for comparison. All materials were biocompatible; however, PeT-G and EVA aligners caused the least tissue irritation. Patients preferred TPU aligners for initial comfort and PeT-G aligners for transparency and endurance. Conclusion: Biocompatible PeT-G, PP, PC, TPU, and EVA tooth aligners fix malocclusions. Aligner materials should be chosen based on patient preferences, treatment goals, and material qualities. For stronger proof, a longer-term study is needed.

In this study, we investigated the impact of chain extenders with varying numbers of carbon atoms (2–6) on the thermal degradation behavior of thermoplastic polyurethanes based on diol carbonate (TPU) in air and nitrogen atmospheres. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were utilized to evaluate phase separation and thermal degradation, respectively. The experimental data provided valuable insights into the thermal degradation of TPUs and the mechanisms involved in the process. In addition, the physical/chemical nature of the process was considered when explaining the degradation mechanisms. Our results showed that the 4-carbon chain extender exhibited a longer average degradation time than the other chain extenders due to the stabilization of the urethane bond, as confirmed by both ANSI/ASTM D-2307 and the artificial neural network (ANN). Using the isoconversional method and an ANN approach, we obtained reliable kinetic data that allowed us to predict the materials' endurance time and thermal degradation behavior by constructing a dedicated network. This proposed methodology can be applied to other materials and characterization techniques, provided sufficient data is available. Overall, this study contributes to a better understanding of the thermal degradation behavior of TPUs and provides insights that can help develop more robust and durable materials for various applications. [ABSTRACT FROM AUTHOR]

Objective: This systematic review examines the efficacy and biocompatibility of orthodontic clear aligner tooth aligners constructed from polyethylene terephthalate glycol (PeT-G), polypropylene (PP), polycarbonate (PC), thermoplastic polyurethanes (TPUs), and ethylene-vinyl acetate (EVA). Materials and Methods: To find relevant papers published through September 2021, PubMed was searched extensively. Randomized clinical trials (RCTs) and observational studies assessing the effectiveness and biocompatibility of the aligner materials were included. Data were extracted independently, and the quality of included research was appraised using relevant procedures. The research variability necessitated a narrative synthesis. Results: Five studies were included for comparison. All materials were biocompatible; however, PeT-G and EVA aligners caused the least tissue irritation. Patients preferred TPU aligners for initial comfort and PeT-G aligners for transparency and endurance. Conclusion: Biocompatible PeT-G, PP, PC, TPU, and EVA tooth aligners fix malocclusions. Aligner materials should be chosen based on patient preferences, treatment goals, and material qualities. For stronger proof, a longer-term study is needed. [ABSTRACT FROM AUTHOR]

Because of the significant effect of geometry on the mechanical properties of auxetic structures, this work focuses on enhancing the re‐entrant hexagonal honeycomb properties, as an auxetic cellular structure with widespread use, by modifying its unit cell's geometry. Herein, six novel structures with additional struts added as supports to the structure are designed to improve the specific energy absorption capacity and flexural modulus. The results reveal that adding supports significantly increases the maximum force tolerated by the structure in the same undergone displacement as the conventional re‐entrant. Furthermore, the findings indicate that honeycombs with concave curved supports outperform conventional re‐entrant honeycombs, showing a significant enhancement in flexural modulus (Ef) by ≈282%, energy absorption, and specific energy absorption by over 297%. Moreover, angle support structures demonstrate outstanding outcomes compared to simple straight supports and single‐support structures. Additionally, a parametric study is carried out using the validated finite‐element model to analyze the influence of the supports' thickness and radius as well as the distance between the middle of the unit cell and the support (L3) in honeycombs with concave curved supports and the β angle of angle supports in the double‐angle support structures. [ABSTRACT FROM AUTHOR]

A series of CO2-based thermoplastic polyurethanes (TPUs) were prepared using CO2-based poly(polycarbonate) diol (PPCDL), 4,4′-methylenebis (cyclohexyl isocyanate) (HMDI), and polypropylene glycol (PPG and 1,4-butanediol (BDO) as the raw materials. The mechanical, thermal, optical, and barrier properties shape memory behaviors, while biocompatibility and degradation behaviors of the CO2-based TPUs are also systematically investigated. All the synthesized TPUs are highly transparent amorphous polymers, with one glass transition temperature at ~15–45 °C varying with hard segment content and soft segment composition. When PPG is incorporated into the soft segments, the resultant TPUs exhibit excellent self-healing and shape memory performances with the average shape fixity ratio and shape recovery ratio as high as 98.9% and 88.3%, respectively. Furthermore, the CO2-based TPUs also show superior water vapor permeability resistance, good biocompatibility, and good biodegradation properties, demonstrating their pretty competitive potential in the polyurethane industry applications.

Thermoplastic polyurethanes (TPU) offer excellent properties for a wide range of dosage forms. These polymers have been successfully utilized in personalized medicine production using fused deposition modeling (FDM) 3D printing (3DP). However, direct powder extrusion (DPE) has been introduced recently as a challenging technique since it eliminates filament production before 3DP, reducing thermal stress, production time, and costs. This study compares DPE and single-screw extrusion for binary (drug-TPU) and ternary (drug-TPU-magnesium stearate [MS]) mixtures containing from 20 to 60% w/w of theophylline. Powder flow, mechanical properties, fractal analysis, and percolation theory were utilized to analyze critical properties of the extrudates. All the mixtures could be processed at a temperature range between 130 and 160 °C. Extrudates containing up to 50% w/w of drug (up to 30% w/w of drug in the case of single-screw extrusion binary filaments) showed toughness values above the critical threshold of 80 kg/mm2. MS improved flow in mixtures where the drug is the only percolating component, reduced until 25 °C the DPE temperature and decreased the extrudate roughness in high drug content systems. The potential of DPE as an efficient one-step additive manufacturing technique in healthcare environments to produce TPU-based tailored on-demand medicines has been demonstrated. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerators (TENGs) are capable of sustainably powering wearable sensors by harvesting diverse forms of ambient mechanical energy. Nevertheless, the material and structural designs of friction layers have significant impacts on the performance of TENGs. Electrospun nanofibers can enhance the electrical performance of wearable TENG because of their large specific surface area and porosity. Herein, the free-surface electrospinning technique was used to prepare the positive and negative friction layers with special structures of TENGs. The porous nanofiber membrane (NFM) of polylactic acid (PLA)/chitosan (CS)/aloin with good biocompatibility was used as the positive friction layer of TENGs. Furthermore, a certain amount of carbon black (CB) nanoparticles (NPs) were loaded into thermoplastic polyurethanes (TPU) to prepare beaded NFMs (BNFMs), which helped to improve the hydrophobicity and charge storage capability of the negative friction layer. The morphology of BNFMs with various CB contents and their electrical output performances as negative friction layers were compared, respectively. It was found that the BNFMs could deform under different pressures to enhance the contact area and electrical output of TENG. Moreover, the BNFMs loaded with CB can not only increase their surface roughness but also enhance the charge transfer rate and storage capacity of the friction layer. This provided TENG with good electrical output, high stability, and durability, as well as great application potential in harvesting various types of biomechanical energies. In addition, the proposed all-electrospun TENG had better flexibility, wearing comfort, and fabricating ease, which could be adhered to the human body for sensing human motion when embedded into textiles. [ABSTRACT FROM AUTHOR]

Thermoplastic polyurethane (TPU) membrane has super physical-mechanical properties and biocompatibility, but the surface is inert and lack of active groups which limit its application in cell culture. Silk sericin (SS) can improve cell adhesion, proliferation, growth and metabolism. In this paper, SS was grafted onto the surface of TPU membrane by -NH2 bridge to build a high efficiency cell culture membrane. The FT-IR spectrum results indicated SS was grafted by chemical bond. According to the SEM and AFM results, we found that the grafting of SS reduced the water contact angle by 43.31% and increased the surface roughness by about four times. When TPU-SS was used for HepG2 cell culture, the cell adhesion rate of TPU-SS was significantly higher than that of the general TCPS cell culture plate, and the cell proliferation rate was close to that of TCPS. FDA/EB staining showed that HepG2 cells remained a better cellular growth behavior. HepG2 cells had higher cell vitality including the albumin secretion and the intracellular total protein synthesis. Grafting SS maintained the stability of cell and significantly decreased the cytotoxicity by decreased LDH release. In conclusion, SS grafting is beneficial to cell culture in vitro, and provides a key material for bioartificial liver culture system. [ABSTRACT FROM AUTHOR]

In 2020, we published a review on the study of semi-crystalline thermoplastic polyurethane elastomers and composites based on the shape memory effect. The shape recovery ability of such polymers is determined by their sensitivity to temperature, moisture, and magnetic or electric fields, which in turn are dependent on the chemical properties and composition of the matrix and the nanofiller. Nanocellulose is a type of nanomaterial with high strength, high specific surface area and high surface energy. Additionally, it is nontoxic, biocompatible, environmentally friendly, and can be extracted from biomass resources. Thanks to these properties, nanocellulose can be used to enhance the mechanical properties of polymer matrices with shape memory effect and as a switching element of shape memory. This review discusses the methods for producing and properties of nanocellulose-based thermo-, moisture-, and pH-sensitive polyurethane composites. The synergistic effect of nanocellulose and carbon nanofillers and possible applications of nanocellulose-based thermoplastic polyurethane biocomposites with shape memory effect are discussed. A brief description of nanocellulose terminology is also given, along with the structure of shape memory thermoplastic polyurethanes. There is significant interest in such materials for three primary reasons: the possibility of creating a new generation of biomaterials, improving the environmental friendliness of existing materials, and exploiting the natural renewability of cellulose sources. [ABSTRACT FROM AUTHOR]

Composite materials are materials with anisotropic properties that are created by combining several different components in a way that allows the best qualities of each component to be used. In this paper, raw materials were used to obtain composite materials of the type TPU/PP/BaTiO3 powder. The thermogravimetric analysis, dynamic differential calorimetry, and scanning electron microscopy were carried out. The preliminary tests for making specific filaments for 3D printing with a diameter of 1.75 mm were carried out on a laboratory extruder. The purpose of the experiment was to develop the optimal extrusion temperatures and the speed of drawing the filament to make filaments with rigorously constant dimensions, and the variation in diameter had a maximum of 10%. [ABSTRACT FROM AUTHOR]

Flammability of Thermoplastic polyurethane (TPU) limits its application in automotive, wires and cables, sports and textile coatings. Endowing TPU with simultaneously improved flame retardancy and smoke‐suppressant will be highly beneficial. Herein, a novel green and efficient condensed phase GO/Mg−Al layered double hydroxides (LDHs) flame retardant for TPU was synthesized by the co‐precipitation of Mg2+ and Al3+ and assembled with graphene oxide (GO) by electrostatic interaction. The unique two‐dimensional layered structure of GO/LDHs has a large specific surface area, which can form a dense and uniform char layer during the combustion process, thus hindering mass and heat transfer between gaseous and condensed phases. The XRD, TEM, SEM and EDS results showed that Mg−Al LDHs and GO/LDHs were successfully synthesized. The thermal, flame retarding and smoke suppression properties of TPU/GO/Mg−Al LDHs were determinated by UL‐94, limiting oxygen index (LOI), cone calorimeter (CCT) and smoke density (SDT). UL‐94 testing results showed that all the TPU/GO/Mg−Al LDHs samples had a vertical combustion rating of V‐0. Compared with pure TPU (19.1±0.2 %), the LOI value of all TPU/GO/Mg−Al LDHs composites are above 27 %. CCT results showed TGAL3 sample displayed the lowest peaks of heat release rate (pHRR) value of 142.9±9.3 Kw m−2. The total heat release (THR) value of TGAL5 is almost 70 % lower than that of pure TPU. In addition, compared to pure TPU, GO/Mg−Al LDHs materials has excellent performance in smoke suppression. The digital photos and Raman spectra of char residue demonstrated that TPU/GO/Mg−Al LDHs materials has a denser carbon layer after combustion. Apart from flame retarding and smoke suppression, the mechanical properties of TPU/GO/Mg−Al LDHs can maintain more than 80 % of the original TPU after addition of GO/LDHs. These results indicates that GO/LDHs composites is a kind of two‐dimensional layered material with unique structure and excellent flame retardant and smoke suppression. [ABSTRACT FROM AUTHOR]

Recently, nanocomposites of polymers have attracted attention due to their advanced features compared to their complement polymer microcomposites. In this study, thermoplastic polyurethane (TPU) was used as a matrix; antimony trioxide (primary flame retardant) and montmorillonite organo-clay (secondary flame retardant), along with benzoflex (plasticizer), were used as fillers to examine their synergistic effect. Nanocomposites of various compositions (TPU-1 to TPU-6) were prepared via the melt-mixing method and compressed to form sheets of the desired dimensions with a compression molding hydraulic press machine. Characterization of the samples was conducted with Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). A tensile test was performed through a universal testing machine (UTM) which showed that the Young's Modulus improved from 147.348 MPa for the pure sample (TPU-1) to 244.568 MPa for TPU-6. A UL-94 test was executed to observe flame retardance. The sample of interest (TPU-6) achieved V-0 classification in UL-94. All these results confirmed the synergistic effect of primary and secondary flame retardants. An optimum increase in fire resistance and mechanical strength was observed for TPU-6. [ABSTRACT FROM AUTHOR]

We prepared different thermoplastic elastomers (TPEs) using an internal mixer. We investigated the properties of thermoplastic polyurethanes (TPUs) produced from prepolymers with various isocyanate content and two different chain extenders to select the most appropriate TPU matrix for preparing thermoplastic vulcanizates (TPVs). Based on the results, we selected a prepolymer with moderate isocyanate content (10%) and the more flexible 1,6-hexanediol as a chain extender and prepared TPVs by dynamic vulcanization with in situ produced TPU. The rubber phase was acrylonitrile-butadiene rubber (NBR) with peroxidic and sulfuric curing with different accelerators. Dynamical mechanical analysis (DMA) results show that the room temperature storage modulus of the TPVs decreases due to the rubber phase. The TPU/NBR-CBS TPV with delayed action accelerator yields the highest tensile and tear strength and elongation at break. TPU/NBR-DCP made with a peroxide-based rubber blend shows similar tensile strength with significantly lower elongation at break and tear strength. The good mechanical properties of TPU/NBR-CBS can be explained by the long induction period, which allowed the rubber phase to disperse before vulcanization took place. In the TPU/NBR-DCP, the peroxide formed bonds not only in the rubber phase but also between the rubber and TPU phases, which is manifested in the high mixing torque and the result of the thermogravimetric analysis (TGA). [ABSTRACT FROM AUTHOR]

To realize the commercialization of sustainable materials, new polymers must be generated and systematically evaluated for material characteristics and end-of-life treatment. Polyester polyols made from renewable monomers have found limited adoption in thermoplastic polyurethane (TPU) applications, and their broad adoption in manufacturing may be possible with a more detailed understanding of their structure and properties. To this end, we prepared a series of bio-based crystalline and amorphous polyester polyols utilizing azelaic acid and varying branched or non-branched diols. The prepared polyols showed viscosities in the range of 504–781 cP at 70 °C, with resulting TPUs that displayed excellent thermal and mechanical properties. TPUs prepared from crystalline azelate polyester polyol exhibited excellent mechanical properties compared to TPUs prepared from amorphous polyols. These were used to demonstrate prototype products, such as watch bands and cup-shaped forms. Importantly, the prepared TPUs had up to 85% bio-carbon content. Studies such as these will be important for the development of renewable materials that display mechanical properties suitable for commercially viable, sustainable products. [ABSTRACT FROM AUTHOR]

Amorphous and low‐crystallinity thermoplastic polyurethane elastomers are shot back and forth between two elongation levels (ε=0.2$\epsilon =0.2$ and ε=1.2$\epsilon =1.2$) and observed between the excitations for 10 s using wide‐angle X‐ray scattering (WAXS) (50 Hz). For orientation analysis, the fiber patterns are projected, expanded in multipoles, and discussed as a function of relaxation time. Normalized WAXS suggests that the oriented halo observed during extension is predominantly due to selective extinction of unfavorably oriented probes (chain bundles). During retraction, neighborhoods and thus clusters are restored. Discussed are the relaxation curves depending on material and the number of load cycles. The separation of the halo into narrow rings introduces "bundle airiness" as a second coordinate. The now bivariate cluster density is the product of two univariate functions. Its factor "airiness distribution" seems to be a material property which is not changed by annealing. In contrast, the bivariate preferred orientation is not product‐separable. Especially with harder materials it shows two bundle ensembles of different airiness. Interactions between the ensembles explain complex trajectories of the orientation–relaxation curves. The formation of the additional airier oriented component is inhibited by annealing in most of the materials studied. In contrast, multiple load changes promote its formation. [ABSTRACT FROM AUTHOR]

Morphing aircraft are one promising solution to reducing the aviation industry’s environmental impact because they can make aircraft more aerodynamically efficient, thereby reducing greenhouse gas emissions. The design of morphing skins is inherently challenging due to the competing design constraints of needing to be stiff out-of-plane to resist pressure loads while being compliant in-plane to minimise actuation energy. Previous work by these authors introduced the novel concept of Geometrically Anisotropic Thermoplastic Rubber (GATOR) morphing skins that take advantage of multi-material 3D printing and structural scaling laws to allow for better compromises between these competing design constraints. In this work, multi material Fused Filament Fabrication methods were used to 3D print the proposed GATOR sandwich panels from two different stiffnesses of thermoplastic polyurethane to demonstrate the manufacturing process and experimentally quantify the performance of some simple embodiments of the GATOR concept. The panels were mechanically tested to determine their flexural and extensional stiffnesses. Results show that the panels can be extended to a stretch ratio of λ  = 1.6 with a linear response at low stretch ratios. The results from the flexural experiments show that the flexible face sheets are capable of withstanding some compression before buckling, which results in a linear behaviour at small forces. These results show the promise of the GATOR skin concept and motivate future development of designs that further exploit the underlying principles of the concept. [ABSTRACT FROM AUTHOR]

New segmented poly(thiourethane-urethane)s (SPTURs) were synthesized by the reaction of 1,1′-methanediylbis (4-isocyanatocyclohexane) (Desmodur W®, HMDI) and poly(ε-caprolactone)diol (PCL) and (methanediyldibenzene-4,1-diyl)dimethanethiol as nonconventional polymer chain extender. FTIR spectroscopy was used for the structural analysis of obtained polymers. The molecular weight distribution was examined by GPC chromatography. Based on the measured contact angles, free surface energy parameters were calculated. Thermal properties of polymers were examined by DSC and TGA, while viscoelastic properties were measured by DMTA. The tensile, adhesive and optical properties were also investigated for the obtained polymers. It was shown that SPTURs were transparent or partially transparent solids with high molar masses up to 84,300 Da. These polymers showed a good resistance to hydrolysis during incubation in Optylite® physiological saline over 8 weeks. Obtained polymers possessed a tensile strength of up to 43.26 MPa, hardness of up to 96.25/59.00 Sh A/D and adhesion to copper of 14.66 MPa. The surface properties of the obtained polymers show that all obtained SPTURs were hydrophilic (CAs for water between 64.07° and 73.12°) with calculated SFE up to 46.69 mN/m. [ABSTRACT FROM AUTHOR]

The new segmented poly(thiourethane-urethane)s (PTURs) based on 1,1′-methanediylbis(4-isocyanatocyclohexane) (HMDI, Desmodur W®), polycarbonate diol (PCD, Desmophen C2200) and (methanediyldibenzene-4,1-diyl)dimethanethiol were synthesized by one-step melt polyaddition method. The obtained PTURs, with a content of 30–60 wt% of the hard segments (HS), were tested in which the influence of changes in the HS content on their properties was determined. The polymers were characterized by Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), thermal analysis (DSC, TGA) and thermomechanical analysis (DMTA). Additionally, tensile strength, optical (refractive index, UV-VIS and color) and surface properties of the obtained polymers (contact angle and surface free energy) and adhesion to copper were examined. FTIR analysis verified the supposed structure of the polymers obtained and showed a complete conversion of the isocyanate groups. TGA analysis confirmed the relatively good thermal stability of the polymers. On the other hand, after performing the DSC analysis, it was possible to state that the obtained materials were partially or completely amorphous, and the microphase separation decreased with increasing HS content in the polymer. Similar observations were made from the DMTA data. In addition, the hardness, tensile strength, modulus of elasticity, storage modulus, adhesion to copper, refractive index and total free surface energy increased with increasing HS content in the polymer. [ABSTRACT FROM AUTHOR]

Background/purpose: The orthodontic aligner becomes popular worldwide in orthodontic therapy as an esthetic alternative to fixed labial braces. This study evaluated orthodontic tooth movement behavior using different aligner materials and attachment shapes for the movement of a single tooth. Materials and methods: First bicuspid extracted resin typodont models were printed with a 3D printer. Three type of attachments, an ellipsoid shape (thick and thin) and a bar, were designed to fit the canine crown surface. Three types of aligner materials, Polyethylene Terephthalate enhanced with glycol (BIOSTAR) Polyethylene Terephthalate (BenQ), and Thermoplastic polyurethanes (TPU) were used to fabricate different aligners. The typodonts with aligners were sunk in a water bath to simulate canine distal movement in vivo. The canine crown, root movement, and long axis angle changes in each step were calculated and recorded. The data were analysed using a oneway ANOVA statistical method. Results: Comparing the three aligners, the changes the long axis of the canine showed that the BENQ group had a smaller change in the long axis angle. The BENQ group canine involved bodily movement, but the canine movement of the BIOSTAR and TPU group involved tipping. Comparing the three attachments, the bar type attachment had more canine crown tipping in the BIOSTAR and TPU groups. The thick and thin ellipsoid-shaped attachments showed no statistical differences in tooth movement. Conclusion: Attachment shape or size had little influence on the bodily movement of the tooth. A high modulus material may thus be suitable for clinical applications.

The basic aim of the research work is to expand the application range of biomaterials in the field of medical by increasing antibacterial and biocompatible behavior of thermoplastic polyurethanes. Blends of thermoplastic polyurethanes with chitosan and starch were prepared through extrusion process. The effect of polysaccharides (corn starch and chitosan) incorporation in thermoplastic polyurethane matrix and polymers interaction on thermal and morphological aspects was investigated. Possible interaction among chitosan and starch within TPU matrix individually and together in a blend were assessed by Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffractometer (XRD). The results indicated that thermoplastic polyurethanes were semi crystalline in nature whereas hydrophilicity of prepared thermoplastic polyurethanes was determined by contact angle. Biological properties endowed that TPU blended with chitosan and starch possessed antibacterial and hemolytic potential. Hence, it can be a suitable candidate for biomedical applications. • Blends of thermoplastic polyurethanes (TPUs) with chitosan and starch were prepared through extrusion process. • The effect in TPUs matrix and polymers interaction on thermal and morphological aspects was investigated. • Possible interaction of TPUs were assessed by FTIR and XRD having semi crystalline in nature. • Biological properties endowed that blended TPU possessed antibacterial and hemolytic potential. [ABSTRACT FROM AUTHOR]

A two‐step grafting procedure has been used to graft tetraethylenepentamine (TEPA) and nano silicon dioxide (SiO2), onto graphene oxide (GO) surface. The resulting modified GO, that was TGOS, which was used as a reinforcement in thermoplastic polyurethanes (TPUs). Mechanical properties, thermal stability and rheological properties of composites were investigated. Results showed that the addition of TGOS significantly improved the mechanical properties of TPU compared with the pure TPU sample. Tensile strength and elongation at break of TPU were increased by 50.8 and 18.6%, respectively, when the addition amount was only 0.5 wt%. TG results showed that the addition of TGOS improved the heat resistance of TPU. Complex viscosity, storage modulus (G') and loss modulus (G") of TPU composites with different additions were analyzed by rheological tests, the results showed that the addition of TGOS improved the deformation resistance of TPU. Meanwhile, TPU composites present high G', G", and complex viscosity with the increase of TGOS filling amount in the low frequency region. [ABSTRACT FROM AUTHOR]

In this work, a novel functionalization strategy for ZIF-67-modified layered MXene was proposed, aiming at improving the fire safety of thermoplastic polyurethanes (TPU). The ZIF-67@MXene was verified by microscopic morphology, elemental composition, functional group species and crystal structure, and then the successfully prepared ZIF-67@MXene was introduced into the TPU material. When ZIF-67@MXene content was only 0.5 wt%, the peak heat release rate, total heat release rate, peak smoke release rate, total smoke release rate, and CO yield of the TPU/ZIF-67@MXene composites were reduced by 26%, 9%, 50%, and 22%, respectively, compared with the pure TPU. The thermogravimetric tests showed that the residual char of TPU/ZIF-67@MXene composites was the most in all samples. In short, the high-quality carbon layer of TPU/ZIF-67@MXene composites acts as a physical barrier to the transfer of heat and toxic gases, greatly improving the flame retardant properties of the TPU polymer. [ABSTRACT FROM AUTHOR]

Polymer materials can be manufactured with high reproducibility and do offer the potential for chemical modification. This enables matrix property modification and fine-tuning of several material characteristics, such as tissue-implant interaction, inflammatory potential or susceptibility to biofilm formation. Whereas manufacturing protocols are crucial for the resulting material properties, also the evaluation in terms of performance and safety has to be considered. Regarding this, both, temperature and composition of test medium may affect the physicochemical properties of implant materials. The present study addresses the influence of test medium compared to dry test conditions, each at two different temperatures, on the mechanical properties of elastomeric film and nonwoven materials.

Great advances have been made in various 3D printing methods for ceramics. Fabrication of Si‐based ceramics using polymer‐derived ceramics (PDCs) is gaining popularity. Using this route, preceramic polymers can be shaped in the polymer state and then pyrolyzed to produce different types of ceramics. Cellular ceramics can be manufactured using this technique. Herein, the novel fabrication of cellular ceramics with a two‐step process using PDCs is reported. First cellular structures are 3D printed with fused filament fabrication (FFF) using thermoplastic polyurethane and impregnated with preceramic polymer polysilazane. Second, pyrolysis of the impregnated structure produces a self‐similar ceramic cellular structure. The impact of 1) catalysts, 2) curing environment, and 3) pyrolysis sequence optimization to form cellular ceramics with fully dense SiOC(N) struts are systemically evaluated. The resultant custom ceramic components can tolerate operating temperatures of 1500 °C and can be manufactured for less than 5% of the cost of competing methods. The ceramic material is shown to be biocompatible and promotes fast cell adhesion. Finally, early‐stage cell activation on the SiOC(N) structure is shown to be tunable by adjusting the porosity with this 3D printing to mimic the bone tissue geometry for bone regeneration. [ABSTRACT FROM AUTHOR]

Recently, nanocomposites of polymers have attracted attention due to their advanced features compared to their complement polymer microcomposites. In this study, thermoplastic polyurethane (TPU) was used as a matrix; antimony trioxide (primary flame retardant) and montmorillonite organo-clay (secondary flame retardant), along with benzoflex (plasticizer), were used as fillers to examine their synergistic effect. Nanocomposites of various compositions (TPU-1 to TPU-6) were prepared via the melt-mixing method and compressed to form sheets of the desired dimensions with a compression molding hydraulic press machine. Characterization of the samples was conducted with Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). A tensile test was performed through a universal testing machine (UTM) which showed that the Young’s Modulus improved from 147.348 MPa for the pure sample (TPU-1) to 244.568 MPa for TPU-6. A UL-94 test was executed to observe flame retardance. The sample of interest (TPU-6) achieved V-0 classification in UL-94. All these results confirmed the synergistic effect of primary and secondary flame retardants. An optimum increase in fire resistance and mechanical strength was observed for TPU-6.

Research and developmental work of bio‐based materials from both renewable resources and biotechnological processes have gained significant interest recently. In this study, bio‐based azelaic acid has been used in combination with succinic and adipic acids to synthesize co‐monomeric polyester polyol soft segments for thermoplastic polyurethanes (TPUs). Hysteresis of TPUs made from co‐monomeric polyester polyols were significantly lower in comparison to the reference TPUs made from monomeric polyester polyols, indicating significant improvement in dynamic properties. In addition, tensile sets of TPUs prepared with co‐monomeric polyester polyols were lower compared to TPUs prepared from monomeric polyester polyols, confirming excellent dynamic properties. Improved dynamic properties of TPUs based on co‐monomeric polyester polyols can be ascribed to a phase‐separated morphology which was quantified as the lowest fraction of bonded urethane from FTIR spectra, reduced crystallinity in differential scanning calorimetry thermograms, narrow tan δ peaks measured using dynamic mechanical analyses, and images from atomic force microscopy. [ABSTRACT FROM AUTHOR]

The orthodontic aligner becomes popular worldwide in orthodontic therapy as an esthetic alternative to fixed labial braces. This study evaluated orthodontic tooth movement behavior using different aligner materials and attachment shapes for the movement of a single tooth. First bicuspid extracted resin typodont models were printed with a 3D printer. Three type of attachments, an ellipsoid shape (thick and thin) and a bar, were designed to fit the canine crown surface. Three types of aligner materials, Polyethylene Terephthalate enhanced with glycol (BIOSTAR) Polyethylene Terephthalate (BenQ), and Thermoplastic polyurethanes (TPU) were used to fabricate different aligners. The typodonts with aligners were sunk in a water bath to simulate canine distal movement in vivo. The canine crown, root movement, and long axis angle changes in each step were calculated and recorded. The data were analysed using a oneway ANOVA statistical method. Comparing the three aligners, the changes the long axis of the canine showed that the BENQ group had a smaller change in the long axis angle. The BENQ group canine involved bodily movement, but the canine movement of the BIOSTAR and TPU group involved tipping. Comparing the three attachments, the bar type attachment had more canine crown tipping in the BIOSTAR and TPU groups. The thick and thin ellipsoid-shaped attachments showed no statistical differences in tooth movement. Attachment shape or size had little influence on the bodily movement of the tooth. A high modulus material may thus be suitable for clinical applications. [ABSTRACT FROM AUTHOR]

To realize the commercialization of sustainable materials, new polymers must be generated and systematically evaluated for material characteristics and end-of-life treatment. Polyester polyols made from renewable monomers have found limited adoption in thermoplastic polyurethane (TPU) applications, and their broad adoption in manufacturing may be possible with a more detailed understanding of their structure and properties. To this end, we prepared a series of bio-based crystalline and amorphous polyester polyols utilizing azelaic acid and varying branched or non-branched diols. The prepared polyols showed viscosities in the range of 504–781 cP at 70 °C, with resulting TPUs that displayed excellent thermal and mechanical properties. TPUs prepared from crystalline azelate polyester polyol exhibited excellent mechanical properties compared to TPUs prepared from amorphous polyols. These were used to demonstrate prototype products, such as watch bands and cup-shaped forms. Importantly, the prepared TPUs had up to 85% bio-carbon content. Studies such as these will be important for the development of renewable materials that display mechanical properties suitable for commercially viable, sustainable products.

In this work, a novel functionalization strategy for ZIF-67-modified layered MXene was proposed, aiming at improving the fire safety of thermoplastic polyurethanes (TPU). The ZIF-67@MXene was verified by microscopic morphology, elemental composition, functional group species and crystal structure, and then the successfully prepared ZIF-67@MXene was introduced into the TPU material. When ZIF-67@MXene content was only 0.5 wt%, the peak heat release rate, total heat release rate, peak smoke release rate, total smoke release rate, and CO yield of the TPU/ZIF-67@MXene composites were reduced by 26%, 9%, 50%, and 22%, respectively, compared with the pure TPU. The thermogravimetric tests showed that the residual char of TPU/ZIF-67@MXene composites was the most in all samples. In short, the high-quality carbon layer of TPU/ZIF-67@MXene composites acts as a physical barrier to the transfer of heat and toxic gases, greatly improving the flame retardant properties of the TPU polymer.

Copyright of Polimery is the property of Industrial Chemistry Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Polimery is the property of Industrial Chemistry Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, new thermoplastic sulfur-containing poly(carbonate-urethane)s (PCURs) were synthesized via a one-step melt polyaddition from diphenylethane-derivative diols with two or ten methylene groups in the aliphatic chain, i.e., 4,4′-(ethane-1,2-diyl)bis(benzenethioethanol) (diol E) and 4,4′-(ethane-1,2-diyl)bis(benzenethiodecanol) (diol D) as nonconventional chain extenders, 1,1′-methanediylbis(4-isocyanatobenzene) and 20–60 mol% poly(hexane-1,6-diyl carbonate) diol of M ¯ n = 860 g mol−1 as a soft segment. The PCURs were studied mainly to describe their thermal and mechanical behaviors by means of DSC, TG and TG coupled with FTIR, and Shore hardness and tensile tests. Moreover, their structure and physicochemical and adhesive properties were determined. The results of the study showed that the kind of the chain extender as well as soft-segment content had an impact on the properties of the polymers obtained. They were amorphous or semicrystalline high molar mass materials. The PCURs based on diol D exhibited lower glass transition temperatures in comparison with those based on diol E with shorter aliphatic chain (− 1–24 °C vs. 13–55 °C). Unfortunately, the former polymers revealed somewhat poorer tensile strengths (up to 45.0 MPa vs. 51.8 MPa). Nevertheless, these values were similar to or higher than those obtained for their commercial analogs. The PCURs being diol D derivatives also showed, in general, lower hardness and the modulus of elasticity but higher elongation at break. All the PCURs exhibited a relatively good thermal stability. However, the polymers derived from diol D revealed higher temperatures of 1, 10 and 50% mass losses compared with diol E-based ones (290–298 °C vs. 285–287 °C, 325–336 °C vs. 314–323 °C, 360–381 °C vs. 348–356 °C, respectively). The newly synthesized sulfur-containing PCURs showed better adhesive properties to copper than the analogous polymer based on butane-1,4-diol as a chain extender. [ABSTRACT FROM AUTHOR]

The man aim of this work was to investigate the effect of the molecular weight of polyols, mixture of prepolymers, and [NCO]/[OH] molar ratio used during the prepolymer chain extending step on the chemical structure, thermomechanical and mechanical properties, and thermal stability of thermoplastic poly(ether-urethane)s In this work thermoplastic poly(ether-urethane)s were synthesized by using polyols with a various molecular weight, 4,4′-diphenylmethane diisocyanate and bio-based glycol. Materials were obtained by a two-step method. The tests were carried out for polyurethanes obtained from a mixture of prepolymers and for reference samples. In the case of materials obtained with using mixture of prepolymers, the ratio of both prepolymers was determined on 50/50 weight percent. Soft segments of materials prepared with using mixture consist of two different polyols. The chemical structure was analyzed using FTIR spectroscopy. The Gaussian deconvolution technique was used to study the hydrogen bonding as well as to decompose carbonyl region of three peaks in various TPUs. The thermal degradation behavior was investigated by using thermogravimetric analysis at heating rates of 10 °C/min. It was confirmed that the mixture of prepolymers has an effect of the degree of phase separation, thermal stability and selected properties of synthesized thermoplastic poly(ether-urethane)s. [ABSTRACT FROM AUTHOR]

Ternary polyoxymethylene (POM) blends comprising methacrylate-butadiene-styrene (MBS) copolymer and thermoplastic polyurethanes (TPU) in different weight percentages are prepared by a two-step melt extrusion technique. The synergistic toughening effect of polyoxymethylene by MBS as the impact modifier and TPU as the compatibilizer is investigated. The thermal behaviors of the prepared POM/MBS/TPU blends are analyzed. The notched impact resistance of the modified POM (POM/MBS/TPU 80 wt%/15 wt%/10 wt%) reached 40.83 kJ m-2. The enhanced toughness of the POM/MBS blends with the incorporation of TPU indicates the significance of TPU as a compatibilizer. Although the TPU compatibilizer enhances the interfacial adhesion between POM and MBS and decreases the size of MBS particles, serious agglomeration phenomenon is observed at higher TPU contents (more than 10 wt%) and caused slightly reduced tensile strength and the elongation at break for the sample with both loadings of MBS and TPU at 15 wt%. Instead, further increase of the notched impact strength is noted resulting from the compatibilizer TPU and an effective impact modifier MBS on the POM blend system to achieve a "super-tough" effect. These "super-tough" polyoxymethylene blends can be applied as the host matrix for preparing various multifunctional nanocomposites. [ABSTRACT FROM AUTHOR]

Highlights • Electrospun TPU/PDMS/PMMA membrane exhibited hydrophobicity and organophilicity. • Membrane tensile strength increased 12.6 times after adding TPU in electrospinning. • Self-bundled fiber yarns and point-bonded structure improved mechanical property. • MARS was developed with ETPPM to achieve phenol separation from saline wastewater. Abstract Electrospun poly(dimethyl siloxane)/poly(methyl methacrylate) (PDMS/PMMA) membrane (EPPM) is an emerging material in membrane aromatic recovery system (MARS) for phenol separation from saline wastewater. However, its application and performance in MARS are hindered by poor mechanical property. To solve this issue, thermoplastic polyurethanes (TPU) was mixed with PDMS and PMMA to fabricate novel electrospun TPU/PDMS/PMMA membrane (ETPPM). Membrane morphologies showed that intrinsically random oriented fibers of EPPM were gradually changed into the self-bundled fiber yarns with point-bonded structure, which led to the tensile strength and elongation at break of ETPPM-3 increased 12.6 times and 89.9%, respectively after 1.5 g TPU addition. Furthermore, ETPPM-3 presented a simultaneous organophilic and hydrophobic surface with phenol static contact angle of 0° and NaCl solution static contact angle of 143.4°, indicating its potential in phenol separation from saline wastewater. After 24 h MARS operation, 498.3 mg L−1 of phenol was separated from the initial phenol saline wastewater (2.0 g L−1 phenol and 10.0 g L−1 NaCl) with a conductivity increase of 21.2 µs cm−1. As a result, 24.9% of phenol recovery and 99.86% of salt rejection were achieved with mean phenol mass transfer coefficient of 7.3 × 10−7 m s−1 and flux of 4.4 × 10−4 kg m−2 s−1. [ABSTRACT FROM AUTHOR]

The wear resistance of several thermoplastic polyurethanes (TPUs) having different chemical nature and micronscale arrangement of the hard and soft segments has been investigated by means of erosion and abrasion tests. The goal was correlating the erosion performances of the materials to their macroscopic mechanical properties. Unlike conventional tests, such as hardness and tensile measurements, viscoelastic analysis proved to be a valuable tool to study the erosion resistance of TPUs. In particular, a strict correlation was found between the erosion rate and the high-frequency (~107 Hz) loss modulus. The latter reflects the actual ability of TPU to dissipate the impact energy of the erodent particles.

Hybrid organic-inorganic metal halide perovskite solar cell (PSC) technology is experiencing rapid growth due to its simple solution chemistry, high power conversion efficiency (PCE), and potential for low-cost mass production. Nevertheless, the primary obstacle preventing the upscaling and widespread outdoor deployment of PSC technology is the poor long-term device stability, which stems from the inherent instability of perovskite materials in the presence of oxygen and moisture. To address this issue, in this work, we have synthesized a series of thermoplastic polyurethanes (TPUs) through a rational design by utilizing polyols having different molecular weights and diverse isocyanates (aromatic and aliphatic). Thorough characterization of these TPUs (ASTM and ISO standards) along with structure-property relationship studies were carried out for the first time and were then used as the encapsulation material for PSCs. The prepared TPUs were robust and adhered well with the glass substrate, and the use of low temperature during the encapsulation process avoided the degradation of the perovskite absorber and other organic layers in the device stack. The encapsulated devices retained more than 93% of their initial power conversion efficiency (PCE) for over 1000 h after exposure to harsh environmental conditions such as high relative humidity (80 ± 5% RH). Furthermore, the encapsulated perovskite absorbers showed remarkable stability when they were soaked in water. This article demonstrates the potential of TPU as a suitable and easily scalable encapsulant for PSCs and pave the way for extending the lifetime and commercialization of PSCs.

Novel tough hydrogel materials are required for 3D-printing applications. Here, a series of thermoplastic polyurethanes (TPUs) based on poly(e-caprolactone)-b-poly(ethylene glycol)-b-poly(e-caprolactone) (PCL-b-PEG-b-PCL) triblock copolymers and hexamethylene diisocyanate (HDI) were developed with PEG contents varying between 30 and 70 mol%. These showed excellent mechanical properties not only when dry, but also when hydrated: TPUs prepared from PCL-b-PEG-b-PCL with PEG of Mn 6 kg/mol (PCL7-PEG6-PCL7) took up 122 wt.% upon hydration and had an E-modulus of 52 ± 10 MPa, a tensile strength of 17 ± 2 MPa, and a strain at break of 1553 ± 155% in the hydrated state. They had a fracture energy of 17976 ± 3011 N/mm² and a high tearing energy of 72 kJ/m². TPUs prepared using PEG with Mn of 10 kg/mol (PCL5-PEG10-PCL5) took up 534% water and were more flexible. When wet, they had an E-modulus of 7 ± 2 MPa, a tensile strength of 4 ± 1 MPa, and a strain at break of 147 ± 41%. These hydrogels had a fracture energy of 513 ± 267 N/mm² and a tearing energy of 16 kJ/m². The latter TPU was first extruded into filaments and then processed into designed porous hydrogel structures by 3D-printing. These hydrogels can be used in 3D printing of tissue engineering scaffolds with high fracture toughness. [ABSTRACT FROM AUTHOR]

Thermoplastic polyurethanes (TPUs) from fatty acids dimer-based polyester polyols, 4,4′-methylene bis(phenyl isocyanate) (MDI) and isosorbide (ISO) as chain extender were successfully synthesized by a two-stage synthesis. TPUs obtained from isosorbide were compared to the model 1,4-butanediol (BDO) −based materials. Differential scanning calorimetry revealed the phase-separated structure of these materials that displayed a typical thermoplastic elastomer behavior by dynamic mechanical analysis. Samples were further analyzed by transmission electronic microscopy, atomic force microscopy and compression set; hardness and water uptake were also monitored. Isosorbide was found to slightly increase the glass transition and melting temperatures of MDI-based hard segments, and to slightly decrease the stability and quality of phase segregation. This resulted in an increase in rubber modulus and hardness, shape retention, in a slight increase in the temperature of the α relaxation of the soft segment domains and in a characteristic microphase morphology. Moreover the use of the rather hydrophobic fatty acid-based soft segment allowed to keep the water uptake at a rather low level, in spite of the presence of isosorbide in the formulation. [ABSTRACT FROM AUTHOR]

A simple non-isocyanate route synthesizing thermoplastic polyurethanes (TPUs) with good thermal and mechanical properties is described. Melt transurethane polycondensation of dimethyl 1,6-hexamethylene dicarbamate with 1,4-butanediol and 1,6-hexanediol was conducted at different molar ratios under the catalysis of tetrabutyl titanate. A series of crystallizable non-isocyanate TPUs with high molecular weight were prepared. The TPUs were characterized by gel permeation chromatography, FT-IR, 1H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide angle X-ray diffraction, AFM, and tensile tests. The TPUs exhibited Mn ranging from 12 500 to 26 400 g/mol, Mw from 16 700 to 56 400 g/mol, Tm up to 151.4 °C, and initial decomposition temperature over 241.8 °C. Their tensile strength reached 42.99 MPa with a strain at break of 30.00%. TPUs constructed simply with butylene, hexylene, and urethane linkages were successfully synthesized through a non-isocyanate route. [ABSTRACT FROM AUTHOR]