Polyurethane Gel Research Articles

CdS/CuInS2 Quantum Dots Cosensitized Solar Cells Using Functionalized Polyurethane Gel Electrolytes

CdS/CuInS2 Quantum Dots Cosensitized Solar Cells Using Functionalized Polyurethane Gel Electrolytes

Preparation and properties of multi-responsive self-healing non-isocyanate polyurethane gel coating

ABSTRACT Traditional polyurethane coating is prepared by combining isocyanate and polyol, but isocyanate is toxic, which is not conducive to the sustainable development of ecological environment. In this paper, dibutyltin dilaurate (DBTDL) was used as catalyst to synthesize dicyclic carbonate from four different acids and glycerol carbonates. Then, it was gradually polymerized with isophorone diamine (IPDA) and 4,4’-diaminodiphenyl disulfide ether to synthesize self-healing non-isocyanate polyurethane (NIPU). The effects of different acid types on coating forming and self-healing properties of NIPU were studied. Then, polypyrrole modified carbon nanotubes were prepared and physically blended with NIPU to obtain a responsive NIPU gel coating. The results show that NIPU has excellent scratch repair performance at 70°C by optical microscopy; Through the dissolution and re-formation of NIPU by N, N-dimethylformamide, it is proved that the material has repeatable processability and is conducive to the sustainable development of ecological environment; The high precision multimeter proved that NIPU has the responsiveness under different chemical environment of acid, alkali, oxidation and reduction. The coating has broad application prospects in biomimetic technology, biology, electronics and other fields.

Polypropylene composite mesh modified by polyurethane gel with ROS scavenging and anti-inflammatory effects for pelvic floor repair.

Development of an inflammation modulating polypropylene (PP) mesh in pelvic floor repair is an urgent clinical need. This is because PP mesh for pelvic floor repair can cause a series of complications related to foreign body reactions (FBR) in postoperative period. Therefore, we successfully prepared PP composite mesh that can scavenge reactive oxygen species (ROS) and inhibit inflammation to moderate FBR by a simple method. First, a pregel layer was formed on PP mesh by dip coating. Among them, polyurethane with polythioketal (PTK) is an excellent ROS scavenger, and dopamine methacrylamide (DMA) improves the stability of the coating and synergistically scavenges ROS. Then, a composite mesh (optimal PU50-PP) was obtained by photopolymerization. The results showed that the polyurethane gel layer was able to scavenge more than 90% of free radicals and about 75% of intracellular ROS. In vitro, PU50-PP mesh significantly scavenged ROS and resisted macrophage adhesion. After implantation in the posterior vaginal wall of rats, PU50-PP eliminated 53% of ROS, inhibited inflammation (decreased IL-6, increased IL-10), and dramatically reduced collagen deposition by about 64%, compared to PP mesh. Thus, the composite PP mesh with ROS scavenging and anti-inflammatory properties provides a promising approach for mitigating FBR.

Non-toxic CuInS2 quantum dot sensitized solar cell with functionalized thermoplast polyurethane gel electrolytes

Functionalization of multi-walled carbon nanotubes (CNTs) was carried out through ultrasonication in acidic medium followed by chemical attachment of thermoplastic polyurethane and subsequent chain extension using butane-diol to obtain CNT-tagged polyurethane (PU-CNT). PU-CNT was functionalized by using propane sultone as a sulfonating agent to attach the pendent sulfonate moiety on urethane linkage. The functionalization of CNTs, tagging of CNTs with polymer chain, chain extension and subsequent functionalization of polymer have been confirmed though through spectroscopic techniques such as NMR, FTIR, UV–vis, and Raman spectroscopy. Thermal stability and the nature of interaction is explored through thermal measurements to understand the effect of CNT functionalization. Electrical conduction has been improved by the chemical attachment of CNTs with polymer (1.61 × 10−6 S/cm) which further increases through functionalization (1.37 × 10−4 S/cm) and thereby make them suitable for gel electrolyte. Quantum dot of CuInS2 has been synthesized using DDT as capping agent and its characteristic properties and the dimension are worked out for their suitability as active materials in solar cell. Optical band gap of quantum dots and HOMO/LUMO band structure of functionalized polyurethanes have been measured through UV–vis and cyclic voltametry, and thereby, draw the overall energy diagrams of possible combination of materials. Solar cell devices have been fabricated using the appropriate materials and found improved power conversion efficiency of 0.81% with Au (gold) as counter electrode. The reason behind the better efficiency is understood from the lesser energy gap between HOMO energy level of prepared gel electrolyte (SPU-CNT) and Au (gold) counter electrode, better conductivity and higher rate of hole transportation, to reduce the electron-hole pair recombination.

Antimicrobial adhesive polyurethane gel sheet with cetylpyridinium chloride-montmorillonite for facial and somato prosthesis fastening.

Purpose Existing options for attaching facial and somato prostheses, such as skin adhesives, are problematic because of microbial colonization and skin irritation. This study aims to evaluate the suitability of adhesive polyurethane gel sheets containing cetylpyridinium chloride (CPC)-montmorillonite (Mont) for prosthesis fastening.Methods Adhesive gel sheets were fabricated as mixtures of base resin (99.6 wt% polyol) and hardening agent at a ratio of 3:1 with 0 (control), 2, 5, 10, or 15 wt% CPC-Mont. The controlled release of CPC, antimicrobial activity, in vitro skin irritation, and adhesive force against silicone and human skin at different blending ratios were determined. Statistical analyses of the data were performed using one-way analysis of variance (ANOVA), analysis of covariance (ANCOVA), Tukey's test, or single regression analysis, as appropriate.Results The amount of CPC released increased with the CPC-Mont blending ratio and was linearly proportional to the surface occupation area ratio of CPC-Mont. The samples with >5 wt% CPC-Mont exhibited antimicrobial activity against Staphylococcus aureus at an exposure time of 0 d, and samples with >2 wt% CPC-Mont exhibited antimicrobial activity against Candida albicans at an exposure time of 1 d. All samples were classified as non-irritant based on an in vitro skin irritation test. The adhesive force on the silicone material and human skin decreased with increasing CPC-Mont blending ratio.Conclusions Samples with 5 wt% CPC-Mont are potential candidates as antimicrobial adhesive polyurethane gel sheets for fastening facial and somato prostheses.

Bioequivalent and Non-Aqueous Polyurethane Gel for Ultrasound Phantom

Bioequivalent and Non-Aqueous Polyurethane Gel for Ultrasound Phantom

Non-flammable sandwich-structured TPU gel polymer electrolyte without flame retardant addition for high performance lithium ion batteries

The energy density and cycle stability of lithium-ion batteries (LIBs) are improving, but LIBs are likely to burn or even explode in case of accidents. Therefore, the safety of LIBs has attracted tremendous attention. It is a significant problem to increase battery safety while maintaining cycle stability and energy density of LIBs. We show that thermoplastic polyurethane gel polymer electrolytes (TPU GPE) with no flame retardant have noncombustible characteristics. It is found that LiPF6 can be used as a flame retardant of TPU polymer. When TPU GPE is decomposed by heating, LiPF6 is decomposed into LiF and PF5. When PF5 interacts with H2O, it produces H4P2O7 and H3PO4. TPU nanofiber's protective layer of H4P2O7 and H3PO4 may efficiently isolate oxygen and heat. It was discovered through a pouch cell thermal runaway test that an NCM811 pouch cell with GPE will not burn. The pyrolysis process of LiPF6 in the presence of H2O and O2 was simulated by Amsterdam Modeling Suite. The results reveal that an effective method to solve the fire danger of LIBs successfully is to replace the commercial separator with a TPU membrane. This discovery can effectively promote the commercialization of GPE.

Simulation approach for characterizing the isocyanates reactivity in polyurethane gel reactions

Simulation approach for characterizing the isocyanates reactivity in polyurethane gel reactions

The Influence of the Temperature on the Dynamic Behaviors of Magnetorheological Gel

Magnetorheological (MR) gel is a new generation of MR material, which can overcome disadvantages attaching MR fluid such as sedimentation. MR gel is formed by the soft magnetic particle suspension in the gel‐like matrix and its rheological properties are mainly controlled by the following two factors, i.e., magnetic field and temperature. Herein, MR gel based on polyurethane gel with a 60% weight fraction of carbonyl iron is prepared. The influence of temperature on the rheological characteristics of the MR gel sample is systematically investigated. Oscillatory shear test is used to investigate the impact of temperature on the modulus of the sample. It is observed that temperature has a significant effect on the viscoelastic properties of MR gel. The hysteresis responses activated by harmonic strain signal with frequencies of 0.1, 5, and 15 Hz and amplitude of 10% and 50% under five temperature levels are measured and employed to analyze the viscous and elastic properties of MR gel and the viscoelastic–plastic model is employed to capture the nonlinear hysteresis characteristics. From the analysis results, the viscoelastic–plastic model can predict the hysteresis properties of MR gel accuracy under various temperatures.

Indentation method accounting for thickness effect of viscoelastic layer

AbstractIndentation tests have been widely used to evaluate the mechanical properties of industrial and biological materials in many studies. In this study, we obtained an analytical solution for the axisymmetric contact problem for a viscoelastic layer bonded to a rigid substrate and indented by a flat‐ended cylindrical punch using the elastic–viscoelastic correspondence principle. The analytical solution was obtained from a method using an infinite system of simultaneous equations instead of a conventional method using the second kind of Fredholm equation. Relaxation indentation tests were conducted for silicon rubber, polyurethane gel (a soft material used for elastography), and articular cartilage from a bovine femoral head. The articular cartilage was tested as obtained and then tested again after treatment by collagenase. The viscoelastic models in this study were a three‐element model (standard linear solid model) and a five‐element model (generalized Maxwell model), and the viscoelastic parameters for the models were determined by fitting the analytical solution to results for applied load as it varied over time during relaxation indentation tests. The results suggested that the five‐element model was more appropriate than the three‐element model for reproducing the relaxation indentation behavior of silicon rubber, polyurethane gel, and articular cartilage. Furthermore, the viscoelastic parameters for treated articular cartilage clearly decreased compared with those for unaltered articular cartilage. These results suggest that the method for evaluating the time‐dependent mechanical properties of articular cartilage based on analytical solutions of relaxation indentation tests could be a useful tool for evaluating the state of degenerated cartilage.

Comparison of Interface Pressures and Subjective Comfort of Pressure-Relieving Overlays on the Operating Table for Healthy Volunteers.

(1) Background: Pressure ulcers in the hospital setting occurring within 72 h after surgery are called perioperative pressure injuries. The aim of this study was to provide data for the prevention of perioperative pressure injuries following the use of pressure-relieving overlays by measuring the interface pressures and subjective comfort. (2) Methods: This study is based on a repeated measures design. The subjects included 30 healthy volunteers aged 18 to 57 years. Interface pressures of the sacrum and both heels were measured in the supine position, and the subjective comfort was evaluated with visual analog scale after applying polyurethane foam, gel pad, and egg crate foam for relief. (3) Results: The pressures in the sacrum and both heels were the lowest with polyurethane foam, and the subjective comfort was the highest. (4) Conclusions: Inexpensive polyurethane foam with satisfactory pressure relief is recommended as an overlay for surgical patients.

Gel-polymer electrolytes based on polyurethane ionomers for lithium power sources.

Polyurethanes based on the aminoethers of ortho-phosphoric acid and polyisocyanates of an aliphatic nature were studied as a substrate for the preparation of new polymer electrolyte. The conductivity of polyurethane ionomer samples obtained using the optimal amount of aliphatic polyisocyanates and after keeping them in a 1 M LiBF4 solution in γ-butyrolactone reaches 0.62 mS cm−1. It has been established that the transport of positively charged ions through the polymer matrix is due to the formation of clusters of phosphate ions and their association into the conducting channels. The introduction of carboxylate ions into the conducting channels by modifying the aminoethers of ortho-phosphoric acid with phthalic anhydride leads to an increase in their size and rise in the mobility of cations. As a result, the conductivity of polyurethane gel electrolytes increased to 2.1 mS cm−1.

Functionalized Thermoplastic Polyurethane Gel Electrolytes for Cosensitized TiO2/CdS/CdSe Photoanode Solar Cells with High Efficiency

A polymer gel electrolyte has been developed based on functionalized thermoplastic polyurethane for solar cell devices. Long-chain polyurethane is synthesized, and subsequently, a small pendant moi...

Influence of Temperature, Time and Crosslinking Agent on Structure and Properties of Polyurethane Gel

Polyurethane (PU) gel was synthesized based on methylene diphenyl diisocyanate (MDI) and polyols corporation with 1,1,1-Tris(hydroxymethyl)propane (TMP) as a crosslinking agent. The chemical structure of synthesized polyurethane gel was investigated using Fourier-transform infrared spectroscopy (FTIR). The effects of curing temperature, curing time, and crosslinking concentration on the degree of swelling, gel content and hardness of polyurethane gel are investigated. In addition, the crosslink density and average molecular weight between crosslinking points were determined using the Flory-Rehner equation. The results revealed that the curing temperature had more pronounced effect on degree of swelling and gel content than curing time. As the curing temperature increased the degree of swelling and gel content in polyurethane gel increased. Curing time seem to have a complicated effect on crosslink density and average molecular weight between crosslinking points. The hardness of polyurethane gel tends to increase with increasing crosslinking concentration and curing time.

Base-triggered self-amplifying degradable polyurethanes with the ability to translate local stimulation to continuous long-range degradation.

A new type of base-triggered self-amplifying degradable polyurethane is reported that degrades under mild conditions, with the release of increasing amounts of amine product leading to self-amplified degradation. The polymer incorporates a base-sensitive Fmoc-derivative into every repeating unit to enable highly sensitive amine amplified degradation. A sigmoidal degradation curve for the linear polymer was observed consistent with a self-amplifying degradation mechanism. An analogous cross-linked polyurethane gel was prepared and also found to undergo amplified breakdown. In this case, a trace amount of localized base initiates the degradation, which in turn propagates through the material in an amplified manner. The results demonstrate the potential utility of these new generation polyurethanes in enhanced disposability and as stimuli responsive materials.

Constructing a high-performance quasi-solid-state asymmetric supercapacitor: NaxMnO2@CNT/WPU-PAAK-Na2SO4/AC-CNT

This study constructs a flexible, high-performance, quasi-solid-state, asymmetric supercapacitor (ASC) consisting of a positive electrode of Na+-pre-inserted MnO2 deposited-carbon nanotubes (NaxMnO2@CNT), potassium poly(acrylate) cross-linked water-born polyurethane (WPU-PAAK) gel polymer electrolyte soaked with 1 M Na2SO4, and activated carbon-CNT (AC-CNT) composite (NaxMnO2@CNT/WPU-PAAK-Na2SO4/AC-CNT). The pre-insertion of Na+ enhances the utilization of δ-phase MnO2 and the usage of carbon nanotubes (CNTs) is beneficial to promote the electronic conductivity, achieving the optimal performance of NaxMnO2@CNT with high specific capacitance of 230 and 130 F g−1 at 1 and 20 A g−1 in the designed gel polymer electrolyte, WPU-PAAK-Na2SO4. The specific capacitance of the AC-CNT composite is also optimized to achieve the high specific capacitance of 180 and 127 F g−1 at 1 and 20 A g−1 in the same gel electrolyte. This quasi-solid-state ASC with a high cell voltage of 1.8 V can deliver a high cell capacitance, large specific energy, and good specific power of 36.8 F g−1, 16.38 Wh kg−1 and 1.04 kW kg−1, respectively, at 1 A g−1. This ASC also provides an outstanding area-based cell capacitance, areal energy density and areal power density of 254.4 mF cm−2, 111.92 μWh cm−2 and 10.35 mW cm−2, respectively. This highly flexible ASC with 93.4% cell capacitance retention at a bending angle of 180° exhibits an excellent cycle life (97% capacitance retention in a 10,000-cycle test).

Conductive shape‐memory polyurethane/multiwall carbon nanotube nanocomposite aerogels

ABSTRACTSmart nanocomposite aerogels have promising applications. In this work, different percentages of multiwall carbon nanotube (MWCNT) added into synthesized polyurethane (PU) gel in the molten state, using a two‐roll mill. By soaking the PU/MWCNT nanocomposite gel into the water, PU/MWCNT hydrogels containing more than 90 wt % of water were prepared. The obtained hydrogels were freeze‐dried to produce aerogel counterparts. The aerogels were fully characterized using mercury porosimetry, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy (FE‐SEM). The electrical percolation threshold of conductive aerogel system was measured. The shape‐memory behavior of PU/MWCNT nanocomposite aerogels was evaluated by dynamic mechanical thermal analysis (DMTA). The results of the DMTA showed that by adding 2.75 wt % of MWCNT, the recovery ratio and storage modulus of the PU/MWCNT nanocomposite aerogel increased 42 and 180%, respectively. The electrical conductivity of the system also increased three orders of magnitude at the percolation threshold. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48602.

Mechanical Properties of Double Network Poly (Acrylic Acid) Based Hydrogels for Potential Use as a Biomaterial.

Load-bearing applications of hydrogels include soft robots, tissue engineering, and stretchable electronics. This paper presents an extensive study of double network poly (acrylic acid) based hydrogel on stress relaxation, compression fatigue, shear stress, and shock absorption properties as a potential load-bearing soft tissue replacement biomaterial. Double network poly (acrylic acid) hydrogel was selected due to simple processing and availability. The optimized formulation of poly (acrylic acid) hydrogel was used for samples preparation. The compression modulus varied with hydrogel formulation, crosshead speed and swelled amount of the hydrogel. Stress relaxation and shock absorption properties of hydrogel were compared with polyurethane gel used in soft insoles (Shore 5A). Developed hydrogel displayed good fatigue properties up to 10,000 loading cycle at maximum stress of 390±30 kPa and at 84±4% strain. Further, maximum average shear stress and shear modulus of 80 kPa and 140 kPa respectively were observed at 84% strain before fracture.

Analysis and optimisation of an insulated water tank for the domestic purpose

Hot water storage in the insulated tank is an effective method of energy storage and also fills the permanent and intermittent domestic need for hot water. In this study, an insulated water tank with 29 litres capacity is developed, and its energy storage performance is analysed through numerical simulation method. Silica gel and Polyurethane are the insulation materials attached to the concrete tank. This water tank is optimised for minimum cost and temperature loss using grey relation analysis (GRA) and response surface method (RSM). The thickness of concrete, polyurethane and silica gel layer are the considered control parameters. The best value obtained from the two optimisation methods are compared, and from GRA method, thickness of concrete, polyurethane and silica gel are identified as 7.5cm, 0.25cm and 0.25cm, respectively. Finally, from the confirmation test, the temperature loss in 24 hours is predicted as 6.29°C with a minimum material cost for the tank as 5914 INR.

Cell reprogramming by 3D bioprinting of human fibroblasts in polyurethane hydrogel for fabrication of neural-like constructs

3D bioprinting is a technique which enables the direct printing of biodegradable materials with cells into 3D tissue. So far there is no cell reprogramming in situ performed with the 3D bioprinting process. Forkhead box D3 (FoxD3) is a transcription factor and neural crest marker, which was reported to reprogram human fibroblasts into neural crest stem-like cells. In this study, we synthesized a new biodegradable thermo-responsive waterborne polyurethane (PU) gel as a bioink. FoxD3 plasmids and human fibroblasts were co-extruded with the PU hydrogel through the syringe needle tip for cell reprogramming. The rheological properties of the PU hydrogel including the modulus, gelation time, and shear thinning were optimized for the transfection effect of FoxD3 in situ. The corresponding shear rate and shear stress were examined. Results showed that human fibroblasts could be reprogrammed into neural crest stem-like cells with high cell viability during the extrusion process under an average shear stress ∼190 Pa. We further translated the method to the extrusion-based 3D bioprinting, and demonstrated that human fibroblasts co-printed with FoxD3 in the thermo-responsive PU hydrogel could be reprogrammed and differentiated into a neural-tissue like construct at 14 days after induction. The neural-like tissue construct produced by 3D bioprinting from human fibroblasts may be applied to personalized drug screening or neuroregeneration. Statement of SignificanceThere is no study so far on cell reprogramming in situ with 3D bioprinting. In this manuscript, a new thermoresponsive polyurethane bioink was developed and employed to deliver FoxD3 plasmid into human fibroblasts by the extrusion-based bioprinting. When the polyurethane gel was extruded through the syringe tip, the shear stress generated may have caused the transient membrane permeability for transfection. The shear stress was optimized for transfection in situ by 3D bioprinting. We demonstrated that human fibroblasts could be reprogrammed into neural crest-like stem cells by 3D bioprinting with the gel, and the reprogrammed cells underwent neural differentiation in the printed structure after induction. The neural-like tissue engineering constructs fabricated by 3D bioprinting from human fibroblasts may be applied for neuroregeneration or further developed as mini-brain for basic research and drug screening.