Poly Ether Urethane Research Articles

Design of PEG-based hydrogels as soft ionic conductors.

Conductive hydrogels have gained interest in biomedical applications and soft electronics. To tackle the challenge of ionic hydrogels falling short of desired mechanical properties in previous studies, our investigation aimed to understand the pivotal structural factors that impact the conductivity and mechanical behavior of polyethylene glycol (PEG)-based hydrogels with ionic conductivity. Polyether urethane diacrylamide (PEUDAm), a functionalized long-chain macromer based on PEG, was used to synthesize hydrogels with ionic conductivity conferred by incorporating ions into the liquid phase of hydrogel. The impact of salt concentration, water content, temperature, and gel formation on both mechanical properties and conductivity was characterized to establish parameters for tuning hydrogel properties. To further expand the range of conductivity available in these ionic hydrogels, 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) was incorporated as a single copolymer network or double network configuration. As expected, conductivity in these ionic gels was primarily driven by ion diffusivity and charge density, which was dependent on hydrogel network formation and swelling. Copolymer network structure had minimal effect on the conductivity which was primarily driven by counter-ion equilibrium; however, the mechanical properties and equilibrium swelling was strongly dependent on network structure. The structure-property relationships elucidated here enables the rationale design of this new double network hydrogel to achieve target properties for a broad range of applications.

4D-Printed Tool for Compressing a Shape Memory Polyurethane Foam during Programming.

Although several force application concepts are known that can be used to deform shape memory polymers (SMPs) within the scope of programming, controlled deformation is challenging in the case of samples with a cylinder-like shape, which need to be homogeneously compressed starting from the lateral surface. To solve this problem, this contribution follows a material approach that takes advantage of four-dimensional (4D) printing. Fused filament fabrication (FFF) was used as an additive manufacturing (AM) technique to produce a thermoresponsive tool in a cylindrical shape from a polyether urethane (PEU) having a glass transition temperature (Tg) close to 55 °C, as determined by differential scanning calorimetry (DSC). Once it was 4D-printed, a sample of laser cut polyester urethane urea (PEUU) foam with a cylindrical wall was placed inside of it. Subsequent heating to 75 °C and keeping that temperature constant for 15 min resulted in the compression of the foam, because the internal stresses of the PEU were transferred to the PEUU, whose soft segments were completely molten at 65 °C as verified by DSC. Upon cooling to -15 °C and thus below the offset temperature of the soft segment crystallization transition of the PEUU, the foam was fixed in its new shape. After 900 days of storage at temperatures close to 23 °C, the foam recovered its original shape upon reheating to 75 °C. In another experiment, a 4D-printed cylinder was put into hibernation for 900 days before its thermoresponsiveness was investigated. In the future, 4D-printed tools may be produced in many geometries, which fit well to the shapes of the SMPs to be programmed. Beyond programming SMP foams, transferring the forces released by 4D-printed tools to other programmable materials can further expand technical possibilities.

The Impact of Adding Dioxane Derivatives to Polyurethane Structures on their Performance and Degradation in the Environment

The novel dioxane-polyether polyurethanes underwent a 12-month outdoor soil burial test to look into how they would degrade in a natural setting. The structure, thermal properties, surface features, and mechanical strength of the polyurethane films were compared. The initial chemical structure and subsequent chemical alterations were identified using FTIR spectroscopy. The polyurethane samples were less thermally stable throughout the duration of the soil burial test, according to TG/DTG curves. According to all findings, polyurethanes containing 1,3-dioxane-5,5-dimethanol exhibit excellent physical characteristics and mild degradation levels after being buried in soil for a year. These polyether urethanes can break down if the rigid domain structure is exposed to moisture and if microorganisms can spread into the polymer matrix. The physical properties, surface features, and degradation of polyether polyurethanes can be improved by varying the molar ratios of the hard segment components and the dioxane derivative structures.

The influence of microphase separation structure of silicon-containing polyurethane on its wear resistance

This study incorporated polydimethylsiloxane (PDMS) and a kind of siloxane-based chain extender (SDO) into polyether urethanes (PEU). The correlation between microphase separation structure and mechanical properties, surface properties and wear resistance were investigated using multiple characterization techniques such as DSC, DMA, SAXS, ATR-FTIR, and XPS. The addition of PDMS significantly reduced the friction coefficient of PEU and enhances the hydrophobicity. The addition of SDO helped to improve the compatibility between PDMS and hard segments of PEU as proved by the fact that the glass transition temperatures of PDMS segments were shifted to higher temperatures and the fraction of loosely hydrogen-bonded carbonyls increased. Due to the improved interfacial adhesion between the immiscible segments, the wear resistance of PEU modified by both PDMS and SDO was obviously enhanced.

A Study of the Baking Rheokinetics and Properties of a Thermal Protective Coating Based on Polyether Urethane Rubber with End Epoxy Urethane Groups and Melamine Polyphosphate

A Study of the Baking Rheokinetics and Properties of a Thermal Protective Coating Based on Polyether Urethane Rubber with End Epoxy Urethane Groups and Melamine Polyphosphate

Evaluation of 3D-printed bolus for radiotherapy using megavoltage X-ray beams

A radiotherapy bolus is a tissue-equivalent material placed on the skin to adjust the surface dose of megavoltage X-ray beams used for treatment. In this study, the dosimetric properties of two 3D-printed filament materials, polylactic acid (PLA) and thermoplastic polyether urethane (TPU), used as radiotherapy boluses, were investigated. The dosimetric properties of PLA and TPU were compared with those of several conventional bolus materials and RMI457 Solid Water. Percentage depth-dose (PDD) measurements in the build-up region were performed for all materials using 6 and 10 MV photon treatment beams on Varian linear accelerators. The results showed that the differences in the PDDs of the 3D-printed materials from the RMI457 Solid Water were within 3%, whereas those of the dental wax and SuperFlab gel materials were within 5%. This indicates that PLA and TPU 3D-printed materials are suitable radiotherapy bolus materials.

Synthesis and characterization of non-invasively traceable poly(ether urethane)s for biomedical applications

The ease of real-time visibility of biomedical implants and minimally invasive medical devices is indispensable in radiological imaging to avoid complications and assess therapeutic success. Herein, we prepared a series of polyurethane elastomers with inherent radiopacity, enabling them to be imaged under fluoroscopy. Through an appropriate selection of less toxic intermediates such as 1,6-Diisocyanatohexane (HDI), poly (tetramethylene glycol) (PTMG), and a chain extender, iodinated hydroquinone bis(2-hydroxyethyl) ether (IBHE), new radiopaque polyether urethanes (RPUs) containing about 10.8 to 20.6% iodine contents were synthesized. RPUs were characterized for the physicochemical, thermomechanical and radiopacifying properties. It was observed that the concentration of IBHE had a profound impact on the radiopacity of polyurethanes. RPUs exhibited similar or better radiopacity than an aluminum wedge of equivalent thickness. In-vivo imaging revealed that the RPUs were easily distinguishable from the surrounding tissues. Irrespective of iodine content, all the RPUs were cytocompatible, indicating the suitability of these materials for medical and allied applications.

Aerobic biodegradation of untreated polyester–polyether urethanes by newly isolated yeast strains Exophilia sp. NS-7 and Rhodotorula sp. NS-12

Polyester-urethanes as the most widely used polyurethanes (PUs) are among the most recalcitrant plastics in natural conditions. Among existing approaches for managing and reducing plastic waste, biodegradation as a promising approach to reduce plastic waste pollution has drawn scientific society's attention in recent years. In this study, two polyester–polyether urethane degrading yeasts were isolated and identified as two new strains of Exophilia sp. NS-7 and Rhodotorula sp. NS-12. The results showed that Exophilia sp. NS-7 is esterase, protease, and urease positive, and Rhodotorula sp. NS-12 can produce esterase and urease. Both strains can degrade Impranil® as the sole carbon source with the highest growth rate in 4–6 and 8–12 days, respectively. SEM micrograph revealed PU degradation ability in both strains by showing so many pits and holes in treated films. The Sturm test showed that these two isolates can mineralize PU to CO2, and significant decreases in N–H stretching, C–H stretching, C=O stretching, and N–H/C=O bending absorption in the molecular structure of PU were revealed by the FT-IR spectrum. The detection of the deshielding effect in chemical shifts of the H-NMR spectrum after the treatment also confirmed the destructive effects of both strains on PU films.

Reverse thermo-responsive biodegradable shape memory-displaying polymers

This study introduces shape memory-displaying (SM), reverse thermo-responsive (RTR) biodegradable polymers consisting of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblocks, and polycaprolactone (PCL) segments. The interplay between their composition, morphology and mechanical properties and their SM and RTR behavior was investigated as the polymers degraded. HO-(CL)n-(PEO-PPO-PEO)-(CL)n-OH pentablocks were synthesized and chain extended using hexamethylene diisocyanate (HDI), whereby a range of PFCLn polyether ester urethanes were generated.The PCL blocks formed two different crystalline phases melting at different temperatures, one acting as the net-points and the other as the switching segments.PFCLn polymers displayed remarkable SM behavior, as revealed by their high Rf and Rr values, and RTR behavior, as demonstrated by the significantly higher water uptake levels they attained below their LCST as opposed to above the transition.The polymers retained their RTR behavior as they degraded over the period investigated, while a gradual enrichment in the PCL content was observed as degradation took place. PFCLn polymers retained their excellent SM properties throughout fifteen SM full cycles conducted over two months.The dual SM/RTR functionality of the polymers developed render them especially suitable for a diversity of applications, such as in drug delivery, robotics and sensors.

The role of segmental mixing on the mechanical properties and oxidative stability of polydimethylsiloxane-based polyetherurethane

Polydimethylsiloxane(PDMS) based segmented polyether urethanes (SiPEUs) suffer from poor adhesion between apolar PDMS and polar hard domains, which results in inferior mechanical properties and inadequate stability in long-term implantation. To regulate the interfacial miscibility, three chain extenders attached with different dangling side chains (fluorinated diol FDO, silicone-based diol SDO, and hexyl-based diol HDO) were used in two-step synthesis to modify the polarity of hard segments. Thermal analysis demonstrated a higher glass transition temperature of PDMS and PTMO (poly (tetramethylene oxide)) domain in SDO modified SiPEU(SSPEU) in contrast to the samples extended with FDO and HDO. Fourier transform infrared spectroscopy (FT-IR), small-angel x-ray scattering (SAXS), and dissipative particle dynamics (DPD) simulation further proved that SSPEU was achieved with optimal interfacial miscibility compared with SPEU. The intermediate layers were proposed to be functionally percolated composed of PDMS, PTMO, MDI-SDO, and MDI-BDO units, which promoted oxidative stability under accelerated test in vitro without mechanical compromise.

Field management changes the distribution of mesoplastic and macroplastic in Mollisols of Northeast China

Mesoplastic (MaP) and macroplastic (MeP) coming from plastic mulching tend to cause negative effects on biota in ecosystems. However, it is still not clear how field management influences the distribution of MeP/MaP in soils. In this study, MeP/MaP was investigated in 0–20 and 20–30 cm soil layers of three vegetable fields (3.4–6.5 ha) after 13 years plastic-mulching in Mollisols of Northeast China under different management methods (MM) of fertilization and tillage frequency. The tillage frequency was MM2 > MM1 > MM3, while the fertilization was MM1 > MM2 > MM3. The results showed that polyethylene (PE), polypropylene (PP), polystyrene, polyvinyl chloride, polyethylene terephthalate (PET), polyamide, melamine-formaldehyde resin and polyether urethane were found in soil, and PE (>83.76%, from plastic mulching) was the predominant type of MeP/MaP. MeP abundance was significantly (p < 0.05) higher in MM1 and MM2 than that in MM3 in the 0–20 cm soil layer. MM1 and MM2 had the highest abundance of MeP/MaP of size <4 cm2 and 4–16 cm2, while MM3 had the highest abundance at the size >16 cm2. The broken index of MeP/MaP was significantly (p < 0.05) lower in MM2 compared with MM1 and MM3 in the 20–30 cm soil layer. Both tillage frequency and fertilization accelerate the breaking of plastics, especially since the influence was stronger from fertilization. Compared with original plastics, the PE, PP and PET's carbonyl index was significantly (p < 0.05) higher in the three MMs. Generally, fertilization and frequent tillage can reduce the physical effects of large-sized plastic debris on crop growth and increases the negative effects of small-sized plastic and new pollutants formed on biota in the agroecosystems. MeP/MaP recycling should be strengthened, and the irrigation and rotation of farmland should be carried out when the wind speed is weak to avoid plastic invasion.

Development of an elastomeric resin for digital light processing printing

AbstractSoft pneumatic actuators are ideal for soft robotic applications due to their innate compliance and high power‐weight ratios, but their design is limited by the lack of suitable stretchable materials. In this study, a new highly elastic resin for digital light projection 3D printers, designated ElastAMBER, is prepared from a di‐functional polyether urethane acrylate oligomer, and a blend of two different diluent monomers. ElastAMBER exhibits a viscosity of 1000 mPa s at 40°C, outperforming previously synthesized elastic resins and allowing easy printing at near room temperatures. The 3D‐printed components present an elastomeric behavior with a maximum extension ratio (λ) of 4.02 ± 0.06, ultimate tensile strength of 1.23 ± 0.09 MPa, low hysteresis, and negligible viscoelastic relaxation. Its application in linear soft pneumatic actuators has been demonstrated using a bellows‐like construction. ElastAMBER shows promise for creating intrinsically capacitive sensing actuators, displaying a strong correlation between actuator displacement and capacitance. The developed 3D printable ElastAMBER can find potential applications in sensors and actuators for many soft robotic and human‐machine interface applications.

Composite Materials Based on Iron Oxide Nanoparticles and Polyurethane for Improving the Quality of MRI.

Polyether urethane (PU)-based magnetic composite materials, containing different types and concentrations of iron oxide nanostructures (Fe2O3 and Fe3O4), were prepared and investigated as a novel composite platform that could be explored in different applications, especially for the improvement of the image quality of MRI investigations. Firstly, the PU structure was synthetized by means of a polyaddition reaction and then hematite (Fe2O3) and magnetite (Fe3O4) nanoparticles were added to the PU matrices to prepare magnetic nanocomposites. The type and amount of iron oxide nanoparticles influenced its structural, morphological, mechanical, dielectric, and magnetic properties. Thus, the morphology and wettability of the PU nanocomposites surfaces presented different behaviours depending on the amount of the iron oxide nanoparticles embedded in the matrices. Mechanical, dielectric, and magnetic properties were enhanced in the composites’ samples when compared with pristine PU matrix. In addition, the investigation of in vitro cytocompatibility of prepared PU nanocomposites showed that these samples are good candidates for biomedical applications, with cell viability levels in the range of 80–90%. Considering all the investigations, we can conclude that the addition of magnetic particles introduced additional properties to the composite, which could significantly expand the functionality of the materials developed in this work.

Highly Stretchable and Sensitive Single-Walled Carbon Nanotube-Based Sensor Decorated on a Polyether Ester Urethane Substrate by a Low Hydrothermal Process.

We report a highly stretchable sensor with low-concentration (1.5 wt %) single-walled carbon nanotubes (SWCNTs) on flexible polyether ester urethane (PEEU) yarn, fabricated using a low hydrothermal process at 90 °C. Although SWCNTs restrict the PEEU polymer chain mobility, the resulting ductility of our nanocomposites reduces only by 16.5% on average, initially from 667.3% elongation at break to 557.2%. The resulting electrical resistivity of our nanocomposites can be controlled systematically by the number of hydrothermal cycles. A high gauge factor value of 4.84 is achieved at a tensile strain below 100%, and it increases up to 28.5 with applying a tensile strain above 450%. We find that the piezoresistivity of our nanocomposite is sensitive to temperature variations of 25–85 °C due to the hopping effect, which promotes more charge transport at elevated temperatures. Our nanocomposites offer both a high sensitivity and a large strain sensing range, which is achieved with a relatively simple fabrication technique and low concentration of SWCNTs.

Correlation Between Microplastics Pollution and Eutrophication in the Near Shore Waters of Dianchi Lake

Microplastics have been found in many environmental media such as sea water, coastal tidal flats, terrestrial water, sediments, and organisms. Microplastics pollution in inland freshwater lakes have received extensive attention; however, the correlation between eutrophication and microplastics pollution in freshwater lakes remains unclear. In this study, 24 sampling sites were set up in the near shore surface waters of Dianchi Lake, and the pollution characteristics of microplastics such as abundance, composition, particle size, color, and form were evaluated. Water quality parameters related to eutrophication state were analyzed, and the eutrophication indices were further calculated. Specifically, sample pre-treatment was conducted according to the method issued by National Oceanic and Atmospheric Administration (NOAA) of the United States. The color and morphological characteristics of microplastic samples were observed using a stereoscopic microscope, and counts and particle size measurements were performed using Nano Measure 1.2 software. Parts of the samples were selected, and the polymer composition analysis was performed using micro-Fourier Transform infrared (μ-FTIR) spectroscopy. The indices related to eutrophication level evaluation were tested according to the experimental standard methods issued by the Ministry of Ecology and Environment of China. The results showed that the abundance of microplastics in the near shore waters of Dianchi Lake was between 800 and 6000 n·m-3, with an average value of 2867 n·m-3. The types of polymers detected were polyethylene terephthalate (PET), polyetherurethane (PEU), polypropylene (PP), polyethylene (PE), and polyvinyl acetate (PVAc), respectively. The diameter proportion of microplastics in the range of 0.2-0.5 mm was the highest. Fiber microplastics accounted for the most observed type, followed by fragments and films. Among the 24 monitoring sites, it was found that proportions of severe, moderate, and mild eutrophication and mesotrophication sites accounted for 8.33%, 58.33%, 29.17%, and 4.17% of the total sampling sites, respectively, and the main pollutant was total nitrogen (TN). Microplastics abundances in the near shore waters of Dianchi Lake were significantly positively correlated with TN concentrations (P<0.01), whereas they were negatively correlated with chlorophyll a(Chl-a)concentrations, not reaching a significant level (P>0.05). The microplastics abundance and TN concentrations in the north bank water near the main urban area of Kunming were significantly higher than those in the other three banks. Microplastics and TN were considered to potentially have the same origin and be attributed to the tail water discharge from WWTPs.

Fiber diameter as design parameter for tailoring the macroscopic shape-memory performance of electrospun meshes

Fibrous shape-memory polymer (SMP) scaffolds were investigated considering the fiber as basic microstructural feature. By reduction of the fiber diameter in randomly oriented electrospun polyetherurethane (PEU) meshes from the micro- to the nano-scale, we observed changes in the molecular orientation within the fibers and its impact on the structural and shape-memory performance. It was assumed that a spatial restriction by reduction of the fiber diameter increases molecular orientation along the orientation of the fiber. The stress-strain relation of random PEU scaffolds is initially determined by the 3D arrangement of the fibers and thus is independent of the molecular orientation. Increasing the molecular orientation with decreasing single fiber diameter in scaffolds composed of randomly arranged fibers did not alter the initial stiffness and peak stress but strongly influenced the elongation at break and the stress increase above the Yield point. Reduction of the single fiber diameter also distinctly improved the shape-memory performance of the scaffolds. Fibers with nanoscale diameters (< 100 nm) possessed an almost complete shape recovery, high recovery stresses and fast relaxation kinetics, while the shape fixity was found to decrease with decreasing fiber diameter. Hence, the fiber diameter is a relevant design parameter for SMP.

The study of deuterium permeability of film-forming inhibitors with the addition of fullerenes

In this work, the results of the hydrogen permeability study of a composite film-forming inhibitor are considered. Film-forming inhibitor consists of polyether urethane and synthesized fullerenes C60 and C70 in pure form. Two types of samples were used: uncoated and coated stainless steels with composite polyether urethane/fullerene varnish. The experimental work was based on the study of the dependence of the permeation reduction factor on the temperature in the reactor. For the coated sample, the minimum temperature was 623 K at which the deuterium flux was registered. Here we assume that at temperatures below 573 K the output pressure caused by the deuterium flow through the sample is less than 10−10 Pa. The rate of steady-state flow through a coated sample is significantly lower than for an uncoated one at temperatures 573–673 K. The deuterium penetration rates through the two samples increase and reach similar stationary values starting at 723 K.

Design of a Drug-Eluting Subcutaneous Implant of the Antiretroviral Tenofovir Alafenamide Fumarate

PurposeSexual transmission of HIV has been clinically proven to be preventable with a once-daily oral tablet; however, missed doses dramatically increase the risk of HIV infection. Long-acting subcutaneous implants do not allow the user to miss a dose. A desirable long-acting drug-eluting implant can deliver a constant amount of drug, adjust the delivered dose, and be readily manufactured. We present a long-acting, subcutaneous implant design composed of tenofovir alafenamide hemifumarate (TAF) pellets loaded in a sealed polyether urethane tube for the prevention of HIV transmission.MethodsImplants were prepared with pressed drug pellets and extruded polyurethane tubing. In vitro release rate of implants using different pellet formulations, rate-controlling membranes, and geometries were measured.ResultsTenofovir alafenamide release appeared to be governed by a pseudo-steady state and followed a mass transport model of release from a cylindrical drug reservoir. Implant seal integrity was tested and confirmed using mechanical testing. The inclusion of sodium chloride in the pellet increased the release rate and reduced initial lag. The release was sustained for 100 days.ConclusionsThe release rate of tenofovir alafenamide mechanistically varied with geometry and rate controlling membrane composition. The polyether urethane implant presented herein is modular and tunable to adjust the release rate and duration of the TAF release.

Synthesis and characterization of flame retardant polyurethane: Effect of castor oil polyurethane on its properties

A Flame retardant polyether ester urethane was produced using PPG, phosphorous, phthalic anhydride, and isophorone diisocyanate. For the formulation of polymer blend (PBs), bio-based polyurethane was procured from castor oil (CPU) and was blended with polyether ester urethane (PEEU). The different characterizations were done to determine the effect of bio based polyurethane on the properties of PEEU. The comparative studies show PBs have better properties compared to flame retardant PEEU. The thermal degradation study shows a 30–40% decrease in the rate of thermal degradation in PBs. LOI values of PBs have been decreased by 2–3%. The mechanical properties show that the breaking elongation of PBs has increased with 50–90%, but on the other hand, tensile strength has been decreased from 3 (MPa) to 5 (MPa). The gel content in PBs has increased with 10–20%. The hydrolytic stability and contact angle of PBs have been increased with an increase in the CPU ratio. Soil burial test results show that increasing the ratio of CPU in PBs lowers the rate of bacterial attack on the polymeric chain.

Enhanced Hydrolytic Resistance of Fluorinated Silicon-Containing Polyether Urethanes.

The hydrolysis of a newly synthesized polyether urethane (PEU) that uses polydimethylsiloxane (PDMS) as a second macrodiol and fluorinated diol (FDO) as another chain extender has been studied via immersion in buffer solutions at 70 °C. The hydrolysis process was monitored using scanning electron microscopy (SEM), gel permeation chromatography (GPC), and tensile testing. After aging for 32 weeks, no surface defect was observed on the fluorinated silicon-containing PEUs (FSPEU). Meanwhile, the addition of FDO did not alter the other issues of bulk hydrolysis, such as the changes in molecular weight and mechanical strength. Moreover, microphase separation of FSPEU was suppressed during temperature-accelerated hydrolysis, whereas aging induced a more noticeable phase of morphological change in silicon-modified PEUs (SPEU) due to the hindrance effect of the fluorinated side chains. The formation of hydrolysis-prone allophanate is also reduced in the presence of FDO. FSPEU with enhanced antihydrolysis performance can potentially be applied to biostable medical devices.