Pristine PU Research Articles

Superhydrophobic octadecylamine-modified MIL-101(Cr)@polyurethane sponge composite as an oils/organic solvents sorption material

The pollution due to oil spills causes diverse problems such as water pollution, destruction of habitats, and health issues. An easy process to solve this problem is fabricating hydrophobic sorbents. Metal-organic frameworks (MOFs)@polyurethane (PU) sponges in 3D structures are promising candidates to remove pollutants through sorption due to their intrinsic characteristics of MOFs and PU sponges, including porosity, low density, and mechanical strength. In this research, some novel MOFs@PU sponges were fabricated by incorporating MIL-101(Cr) or octadecylamine (ODA)-modified MIL-101(Cr), m-MIL-101(Cr), into PU sponges using PDMS (polydimethylsiloxane) as an adhesive agent. The prepared materials were investigated by various techniques including Fourier transform infrared (FT-IR), x-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive x-ray (EDS) mapping, water contact angle (WCA), and BET (Brunauer–Emmett–Teller) analyses. The WCA increased from 106.36° for the pristine PU to 145.06° and 157.98° for the as-prepared MIL-101(Cr)@PU and m-MIL-101(Cr)@PU, respectively. The uptake efficiency of the as-obtained sorbents for some oils (olive oil, sesame oil, sunflower oil, hydraulic oil, and diesel) and organic solvents (toluene, dichloromethane, ethyl acetate, chloroform, and n-hexane), as well as the ability of the m-MIL-101(Cr)@PU sponge for separation of diesel oil, chloroform, and toluene from water, were studied. The maximum sorption capacity was 79.83 g g−1 and 97.50 g g−1 for sesame oil and chloroform, respectively, using m-MIL-101(Cr)@PU as sorbent, which was higher than the efficiency of the pristine PU adsorbent. Additionally, the m-MIL-101(Cr)@PU sponge composite exhibited proper reusability of up to 7 cycles (∼52.88 g g−1). Overall, the as-obtained m-MIL-101(Cr)@PU sorbent exhibits promising potential to uptake oil and organic solvent contaminants.

Solution blending preparation of polyurethane/graphene composite: Improving the mechanical and anti-corrosive properties of the coating on aluminum surface

Graphene-based polyurethane composites (PU/G) are prepared by a simple solution blending method to disperse defect-free graphene flakes (prepared via liquid phase exfoliation process) into the polyurethane matrix. The PU/G composite with 1 wt% of graphene flakes performs the significant improvement (∼50 %) of the impact strength (124 kg.cm) and adhesion behavior (∼2.3 MPa) with respect to that of pristine PU. The PU/G coating with 2 wt% of graphene achieves the highest long-term anti-corrosion performance after 150 immersed days in 3 wt% NaCl solution (with the stable impedance modulus of ∼2.7 × 1010 Ω.cm2) or after 2500 h of salt spray exposure in 5 wt% NaCl solution (no corrosive traces detected on aluminum substrate).

Preparation, design, and characterization of an electrospun polyurethane/calcium chloride nanocomposite scaffold with improved properties for skin tissue regeneration

The present research paper explores the potential of electrospun nanofibers in the promising field of skin tissue engineering. Specifically, we propose an advanced preparation and characterization of an electrospun Polyurethane/Calcium Chloride (PU/CaCl2) nanocomposite scaffold, devised to boost the scaffold’s physicochemical and biological properties for skin tissue regeneration. By incorporating CaCl2 into the PU matrix using an electrospinning process, we were able to fabricate a novel nanocomposite scaffold. The morphological examination through Field Emission Scanning Electron Microscope (FESEM) revealed that the fiber diameter of the PU/CaCl2 (563 ± 147 nm) scaffold was notably smaller compared to the control (784 ± 149 nm). The presence of CaCl2 in the PU matrix was corroborated by Fourier-Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA). Furthermore, the PU/CaCl2 scaffold exhibited superior tensile strength (10.81 MPa) over pristine PU (Tensile −6.16 MPa, Contact angle - 109° ± 1° and Roughness - 854 ± 32 nm) and revealed enhanced wettability (72° ± 2°) and reduced surface roughness (274 ± 104 nm), as verified by Contact angle and Atomic Force Microscopy. The developed scaffold demonstrated improved anticoagulant properties, indicating its potential for successful integration within a biological environment. The improved properties of the PU/CaCl2 nanocomposite scaffold present a significant advancement in electrospun polymer nanofibers, offering a potential breakthrough in skin tissue engineering. However, additional studies are required to thoroughly evaluate the scaffold’s effectiveness in promoting cell adhesion, proliferation, and differentiation. We aim to catalyze significant advancements in the field by revealing the creation of a potent skin scaffold leveraging electrospun nanofibers. Encouraging deeper exploration into this innovative electrospun composite scaffold for skin tissue engineering, the PU/CaCl2 scaffold stands as a promising foundation for pioneering more innovative, efficient, and sustainable solutions in biomedical applications.

Anti-bioadhesive polyurethane coatings enhanced by salicylic acid-carboxy-betaine modified nano-silica: Stepwise antifouling mechanism

Environmentally friendly antifouling coatings have received increasing attention in the field of marine infrastructures. In this work, a carboxy-betaine salicylate surface-modified silica nanofiller (QAs-SA@SiO2 NPs) was synthesized and doped in polyurethane coatings (PU) to gain durable antifouling properties. The modified silica NPs were prepared by the covalent bond grafting method and then dispersed in PU paint to produce a kind of composite anti-fouling coating (QAs-SiO2 PU). It is noted that the QAs-SiO2 PU coating can adjust the release rate of salicylate according to environmental pH value. Once the salicylate layer was dissolved, the inner amphoteric carboxy-betaine molecules would be exposed to form a hydrated layer on QAs-SA@SiO2 NPs, thus realizing a step-by-step antifouling performance. The experimental results show that the 7 wt% addition of QAs-SA@SiO2 filler in the PU coating can reduce protein adhesion by 99.1 %, bacterial adhesion by 99.8 %, and chlorella adhesion by 95.0 %, presenting a significant mussels-repellence ability compared to the pristine PU coating. This work may provide a promising approach to designing eco-friendly and durable marine anti-fouling and anti-corrosion coatings.

Preparation and properties of bio-based intumescent flame retardant containing chitosan functionalized ammonium polyphosphate for polyurethane

In this study, chitosan (CS) from fish waste was used to prepare bio-based environmentally friendly flame retardants. After the hydroxyl group (−OH) of CS and the ammonium group (NH4+) of ammonium polyphosphate (APP) underwent reactions, they were filtered and dried to obtain CS-APP. The amino group of CS-APP then reacted with the epoxy group of 4,4′-methylenebis(N,N-diglycidylaniline) (NDY) to form CS-APP-NDY. Isophorone diisocyanate, polyol, and 3-aminopropyltriethoxysilane reacted to form silicon polyurethane. CS-APP-NDY was then mixed with Si-PU to prepare polymer composites. To determine the structure, thermal properties, flame retardancy, and mechanical properties of the composites, Fourier-transform infrared spectroscopy, thermogravimetric analysis, limiting oxygen index (LOI), cone calorimetry, UL-94, thermal analysis-FTIR (TA-FTIR) spectroscopy, universal machine testing, scanning electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy were performed. The TGA results revealed that, after the addition of CS-APP-NDY, char yield increased from 0.5 wt% to 25.8 wt%, and the thermal stability of pristine PU also improved. In addition, the LOI and UL-94 results indicated that, after the addition of CS-APP-NDY, the LOI increased from 18.2% to 26.3%, and the UL-94 level improved from “Fail” to V-1. Overall, these results indicated that the addition of CS-APP-NDY to pristine PU increased its flame-retarding performance.

Tuning of renewable sponge‐like polyurethane physical‐chemical and morphological properties using the pullulan as a reactive filler

AbstractThis study aimed to evaluate the effect of pullulan (Pull) on a renewable polyurethane sponge‐like scaffold synthesized from the Pull mixture with the castor oil‐based polyol and the prepolymer using the situ foaming method. The Pull contents on the sponge‐like are 5, 10, and 20 wt.%. The samples were evaluated by optical microscopy (OM), scanning electron microscopy (SEM), density, Fourier transform infrared spectroscopy (FTIR), contact angle, Thermogravimetry, X‐ray diffraction analysis (XRD), and compression strength test, respectively. FTIR results indicated that Pull was hydrogen‐bonded to PU foam chains and increased the sponge‐like scaffolds density, inducing a decrease in average cell size compared to the pristine PU, confirming that they act as nucleating agents. The Pull addition improved PU foams' hydrophobicity and mechanical properties and caused a thermal stability median between Pull and pristine PU. Thus, all renewable sponge‐like scaffolds were hydrophobics and presented appropriate mechanical behavior, exhibiting better physicochemical properties, and appearing as promising candidates for biomedical applications.

Efficient selective methylene blue adsorption by polyurethane/montmorillonite‐based antifouling electrospun composite membranes

AbstractA robust antifouling membrane with pollutant‐removing capacity is in high demand for industrial wastewater treatment. Here, we report a new multifunctional polyurethane/montmorillonite‐oxidized multi‐walled carbon nanotube (PU/MMT) nanofibrous composite membrane, beneficial for both water filtration and selective methylene blue adsorption. It was observed that oxidized multi‐walled carbon nanotube (o‐MWCNT) imparted high flexibility with a high percentage elongation (318%–405%) to the composites, whereas montmorillonite (Mt) improved the hydrophilicity, antifouling property, and dye adsorption capacity of the fibrous PU membrane. The sample with 20 wt% Mt (PU/20‐MMT) showed a minimum water contact angle of 57°. It showed a high water flux, oil rejection, and flux recovery ratio compared to the pristine electrospun PU membrane. The Hermia fouling mechanism suggested that electrospun PU obeyed an intermediate blocking model, whereas PU/20‐MMT was best fitted with a cake formation model. During adsorption, the cationic dye methylene blue (MB) was selectively adsorbed on the sample from a methyl orange/methylene blue (MO/MB) mixture. It showed a maximum adsorption capacity (qm) of 112.35 mg/g. The anionic dye methyl orange, on the other hand, remained unadsorbed. The adsorption kinetics and the adsorption isotherm were pseudo‐second‐order kinetics and the Langmuir adsorption isotherm, respectively. The developed, robust electrospun composite membrane opens a new avenue for the selective adsorption of MB from dye mixtures and contaminated water.

How to Compare and Select Flame Retardants for Rigid Polyurethane Foam

Although rigid polyurethane foams (RPUFs) have great thermal insulating properties, they have limited usage because pristine PU foams are highly flammable. Therefore, in order to have widespread applications, much attention has been invested in the discovery and study of a vast number of flame retardants. Though there have been countless reports of novel flame retardants, it has been a challenge to select the most appropriate flame retardant for the RPUF of interest. While several comparison studies have been documented in the literature, the focus is on the microstructure, mechanical, and thermal properties. Herein, a relatively comprehensive flame retardant selection process is introduced, which includes more physical and chemical properties characterisations, enabling one to make informed decisions when selecting flame retardants.

Determining the best flame retardant for rigid polyurethane foam—Tris(2‐chloroisopropyl) phosphate, expandable graphite, or silica aerogel

AbstractAlthough rigid polyurethane foams (RPUFs) have great thermal insulating properties such as its low density, low thermal conductivity, and high compressive strength, they have limited usage because pristine PU foams are highly flammable. Therefore, in order to have widespread applications, much attention has been invested in the discovery and study of a vast number of flame retardants. In this work, analysis on the physical, chemical, mechanical, and thermal properties of RPUF composites prepared with industrially‐used flame retardants, namely tris(2‐chloroisopropyl) phosphate (also known as TMCP or TCPP) and expandable graphite (EG), together with the highly promoted silica aerogel, was performed. Taking into account the overall performance, it was found that EG was the best among the three flame retardants investigated.

Immunomodulatory and antimicrobial non-mulberry Antheraea mylitta silk fibroin accelerates in vitro fibroblast repair and regeneration by protecting oxidative stress.

The antimicrobial nature of Antharaea mylitta silk-fibroin (SF) is reported but antioxidant potential and the immunomodulatory role towards the fibroblast cell repair process is not explored. Polyurethane is reported to have inflammatory potential by mononuclear cells directed cytokine release, which can guide fibroblast repair. Present study demonstrates the conjunctive effect of inflammatory PU/SF to regulate the favorable shift from pro-inflammatory to anti-inflammatory cytokine stimulation for accelerated fibroblast repair. Minimal inhibitory concentration of SF was determined against pathogenic strains and the effect of SF was investigated for fibroblast NIH3T3 cell adhesion. SF doses (8, 8.5, 9 mg mL−1) were found to be greater than both the IC50 of DPPH scavenging and the ED50 for NIH3T3 proliferation. Anti-lipid peroxidase (ALP) activity of SF doses and citric acid-treated NIH3T3 cells were compared under hydrogen peroxide (H2O2) induced oxidative stress. 9 mg mL−1 SF showed greater ALP activity than the citric acid standard. SF-driven protection to oxidative damage was measured by viable cell fraction in trypan blue dye exclusion assay where 9 mg mL−1 SF showed the highest viability (p ≤ 0.05). 9 mg mL−1 SF was blended with PU for scaffold (w/v = 2 : 5, 2 : 7, 2 : 9) fabrication. The protective effect of PU/SF (2 : 5, 2 : 7, 2 : 9) against oxidative stress was verified by damaged cell survival in MTT assay and DNA quantification. The highest number of cells survived on PU/SF (2 : 9) at all intervals (p ≤ 0.01) upon oxidative damage; PU/SF (2 : 9) was also fabricated by employing the immobilization technique. Immobilized PU/SF (2 : 9) exhibited a greater zone of microbial inhibition, a higher extent of inhibition to microbial adherence, and caused more LDH release from bacterial cell membrane due to membrane rupture, resulting in bacterial cell death (E. coli, K. pneumoniae, P. aeruginosa, S. aureus) compared to the experimental results shown by blended PU/SF (2 : 9). The protective nature of PU/SF (2 : 9) against oxidative stress was ensured through the LDH activity of damaged NIH3T3 cells. Initial raised IL-6, TNF-alpha (pro-inflammatory cytokines) and lowered IL-8, IL-10 (anti-inflammatory cytokine) profiles coupled with fallen IL-6, TNF-alpha, and elevated IL-8, IL-10 at later hours synergistically progress the inflammatory phase of in vitro scratch wound repair in mononuclear culture treated by PU/SF (2 : 9).

Durability enhancement of low ice adhesion polymeric coatings

Icephobic performance of low-ice adhesion polymeric coatings has been studied intensively for passive ice protection. However, limited efforts were conducted to identify strategies for enhancing the durability of the coatings to maintain low ice adhesion after erosion impact. In this work, we developed and investigated several polyurethane-based nanocomposite and fibre-reinforced coatings to understand the deteriorating behaviour of the coatings under rigorous impinging erosion tests and the subsequent impact on ice adhesion. The inclusion of fillers resulted in up to 38 points increase in Shore hardness relative to the pristine PU coatings. The ice adhesion strengths on 3 wt% nanoparticle-reinforced coatings after the erosion tests were nearly halved, whereas, a 5-fold reduction was observed on 3 wt% fibre-reinforced coatings compared to that of the pure PU coatings. Our results indicated that the incorporation of fillers was effective in reducing the ice anchoring points, and that, after the impingement, the icephobic performance was retained by either lowering surface roughness or by minimizing surface deterioration. Fibres took a more effective role in limiting crack initiation and resisting crack propagation. The ice adhesion strength of the coatings increased from 5.6 kPa to 8.4 kPa with 20 wt% carbon fibres incorporated PU coatings, essentially keeping the adhesion below 10 kPa even after rigorous impinging tests and a ∼10-fold reduction in ice adhesion strength as compared to the pure PU coatings. The incorporation of the fibres led to enhanced durability and retention of excellent icephobic performance via a mechanism that is adaptable to other polymeric coatings.

Functionalized carbon nanotubes based thermo-responsive shape memory blends with enhanced mechanical properties for potential robotics applications

A two-step approach was used to synthesize a thermo-responsive polyurethane and its blends with amino-functionalized-polystyrene (PS) and multiwall carbon nanotubes (MWCNTs) aiming at enhanced mechanical, thermal and shape memory properties. The synthesis of novel shape-memory polyurethane was confirmed by FTIR spectroscopy. SEM analysis of samples revealed excellent interfacial interaction due to chemical and physical interlinking between both polymers (PU synthesized and polystyrene functionalized) and functionalized multiwall carbon nanotubes (FMWCNTs) filler. The significant improvement in mechanical and thermal properties was observed for synthesized blends (PU/modified PS) as the filler content increased. The mechanical properties of PU/modified-PS blend having 3% loading amount of FMWCNTs were enhanced from 28.6 to 59.3 MPa as compared to those of neat PU. Due to proper fabrication and strong interfacial interaction, enhancement in thermal properties was also evident from the results with increasing filler loading amount. A sharp decrease in thermal, mechanical and recovery properties was also evident due to agglomerates net-points formation when loading amount of carbon filler increased from a certain level. Almost 100% shape recoveries were achieved for all samples, but the recovery durations of the samples were different. Modified-PS and FMWCNTs with PU formed three-dimensional interlocked networks which provided excellent mechanical strength, thermal stabilities and efficient shape recovery to the synthesized blends. Shape recovery response time of blends and nanocomposite was also found to decrease almost half of that of the pristine PU (less than 37 s for blends). Enhanced thermal stabilities, tensile properties, smaller shape recovery time, almost 100% shape recovery capabilities and sustainability, all factors favor the potential use of these blended composite materials in robotics, aeronautics, medical devices and high-performance materials in auto-industry.

Temporary consolidation and packaging of fragile cultural relics at underwater archaeological sites to maintain their original state during extraction

The flexible sponge/epoxy composite can wrap underwater artefacts in any shape and forms a protective shell after curing, thus effectively wrapping and reinforcing the artefacts. However, the hydroscopicity of the sponge itself limits the underwater application of the sponge/epoxy composite. In this study, a novel polyurethane sponge was prepared by modified with super‐hydrophobic multi‐wall carbon nanotubes (SH‐MWCNTs@PU sponge). Compared with the pristine PU sponge, the water‐contact angle on the surface of SH‐MWCNTs@PU sponges increased from 103.3 ± 1.82 to 152.6 ± 1.54o, and oily epoxy resin was able to cover the surface completely. The study shows that when SH‐MWCNTs@PU sponges/epoxy resin composite material is used underwater, it prevents both water from entering the sponge and also the inside epoxy resin from overflowing into the water. Moreover, the composite materials have excellent toughness after reinforcement under water (flexural strength = 3.56 MPa) and the soft sponges can be moulded to wrap any type of underwater artefacts. In the laboratory, when taking a broken, three‐dimensional blue‐and‐white porcelain pot as a research subject, the entire retrieval process—temporary stabilization, packaging, extraction and reinforcement material removal—was simulated to evaluate systematically all the technological aspects of safely excavating fragile underwater relics.

Preparation of UV-Curable Low Surface Energy Polyurethane Acrylate/Fluorinated Siloxane Resin Hybrid Coating with Enhanced Surface and Abrasion Resistance Properties.

Low surface energy coatings have gained considerable attention due to their superior surface hydrophobic properties. However, their abrasion resistance and sustainability of surface hydrophobicity are still not very satisfactory and need to be improved. In this work, a series of utraviolet (UV)-curable fluorosiloxane copolymers were synthesized and used as reactive additives to prepare polyurethane acrylate coatings with low surface energy. The effect of the addition of the fluorinated graft copolymers on the mechanical durability and surface hydrophobicity of the UV-cured hybrid films during the friction-annealing treatment cycles was investigated. The results show that introducing fluorosiloxane additives can greatly enhance surface hydrophobicity of the hybrid film. With addition of 2 wt.% fluorosiloxane copolymers, the water contact angle (WCA) value of the hybrid film was almost tripled compared to that of the pristine PU film, increasing from 58° to 144°. The hybrid film also showed enhanced abrasion resistance and could withstand up to about 60 times of friction under a pressure of 20 kPa. The microstructure formed in the annealed film was found to contribute much to achieve better surface hydrophobicity. The polyurethane acrylate/fluorinated siloxane resin hybrid film prepared in this study exhibits excellent potential for applications in the low surface energy field.

Development and blood compatibility evaluation of novel fibrous textile scaffold based on polyurethane amalgamated with Alternanthera sessilis oil for the bone tissue engineering

In the recent decade, the growth of medical textiles is enormous and it paves the sustained development in the quality of life. In this research, an electrospun textile scaffold comprising polyurethane impregnated with Alternanthera sessilis oil was developed for the bone tissue engineering. Morphology analysis showed that the addition of Alternanthera sessilis oil in the polyurethane membrane resulted in reduced fiber diameter (821 ± 140.87 nm) compared to the pristine PU (890 ± 119.11 nm). The presence of Alternanthera sessilis oil in polyurethane membrane was confirmed through hydrogen bond formation as revealed in the infrared analysis. Further, the polyurethane blended with Alternanthera sessilis oil showed hydrophobic (113.7° ± 3.215) and improved surface roughness (329 nm) than the pristine polyurethane (contact angle – 100° ± 0.5774 and Ra – 313 nm). Moreover, the blood compatibility assessments revealed that the developed biocomponent polyurethane/ Alternanthera sessilis oil membrane possesses enhanced anticoagulant nature compared to the pristine polyurethane. Finally, the newly developed biocomponent polyurethane/ Alternanthera sessilis oil membrane with reduced fiber diameter, hydrophobic behavior, improved surface roughness, and enhanced blood compatibility enabled them as a potential candidate for bone tissue regeneration.

A flame‐retardant composite foam: foaming polyurethane in melamine formaldehyde foam skeleton

AbstractA composite foam, polyurethane–melamine formaldehyde (PU/MF) foam, was prepared through foaming PU resins in the three‐dimensional netlike skeleton of MF foam. The chemical structure, morphology, cell size and distribution, flame retardancy, thermal properties and mechanical properties of such composite foam were systematically investigated. It was found that the PU/MF foam possessed better fire retardancy than pristine PU foam and achieved self‐extinguishment. Moreover, no melt dripping occurred due to the contribution of the carbonized MF skeleton network. In order to further improve the flame retardancy of the composite foam, a small amount of a phosphorus flame retardant (ammonium polyphosphate) and a char‐forming agent (pentaerythritol) were incorporated into the foam, together with the nitrogen‐rich MF, thus constituting an intumescent flame‐retardant (IFR) system. Owing to the IFR system, the flame‐retardant PU/MF foam can generate a large bulk of expanded char acting as an efficient shielding layer to hold back the diffusion of heat and oxygen. As a result, the flame‐retardant PU/MF foam achieved a higher limiting oxygen index of 31.2% and exhibited immediate self‐extinguishment. It exhibited significantly reduced peak heat release rate and total heat release, as well as higher char residual ratio compared to PU foam. Furthermore, the composite foam also showed obviously improved mechanical performance in comparison with PU foam. Overall, the present investigation provided a new approach for fabricating a polymer composite foam with satisfactory flame retardancy and good comprehensive properties. © 2018 Society of Chemical Industry

An investigation of remediation and recovery of oil spill and toxic heavy metal from maritime pollution by a new absorbent material

The extremely serious effects of the marine environment pollution due to oil spill, oil slick and toxic heavy metals on the human, ecosystem, and society are clearly seen. Findings of absorbent materials with high absorption capacity and high usage efficiency are being much interested by several researchers. In this work, four samples of absorbent material fabricated after adding, respectively, 5%, 25% of rice straw mass percentage along with 0.5 and 3 mm of rice straw size, four oil types including crude oil, fuel oil (FO), diesel oil (DO), kerosene, and a solution containing toxic heavy metals such as Cd2+, Pb2+, Hg2+ are used for the experimental purposes related to the evaluation of the oil absorption capacity (OAC) and toxic heavy metal, and the oil removal efficiency (ORE) during 120–150 min. As a result, the as-used sample with 25% of rice straw mass and 0.5 mm of rice straw size shows the highest absorption capacity. In addition, the influence of capillary pressure on the OAC and ORE is analysed, the assistance of Scanning Electron Microscope (SEM) for observation of porous structure of rice straw, pristine PU, and the as-fabricated absorbent are also conducted and presented in this study.

Single stage electrospun multicomponent scaffold for bone tissue engineering application

Incorporation of oils in to the polymer matrix results in the improvement of physicochemical and biocompatible properties. A novel polyurethane based composite bone scaffold was fabricated by electrospinning using sunflower and neem oil for the first time. Scanning electron microscopy (SEM) revealed the mean fiber diameter of the electrospun nanocomposite was decreased with the addition of sunflower oil (816 ± 129.54 nm) and sunflower/neem oil (739 ± 130.922 nm) into the PU matrix (890 ± 116.9115 nm). The strong interactions between PU, sunflower oil and neem oil were observed through Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Contact angle analysis depicted the hydrophobic (PU/sunflower oil - 112° ± 1) nature and with the incorporation of neem oil it shifted to hydrophilic (PU/sunflower oil/neem oil - 61.67° ± 2.517) behavior. Further, the tensile strength analysis showed the improvement in the mechanical strength with the addition of sunflower oil (10.62 MPa) and sunflower/neem oil (11.67 MPa) in to the PU matrix (7.12 MPa). In addition, the developed composites exhibited reduced hemolytic index percentage and enhanced blood clotting time through coagulation studies. Moreover, the cytocompatibility investigation revealed the non-toxic nature of the fabricated nanocomposites with human dermal fibroblast (HDF) cells than the pristine PU. Hence, the developed PU based composites rendering better physio-chemical and cytocompatible properties can serve as an alternate substitute for bone tissue engineering applications.

Ionic Conductive Polyurethane-Graphene Nanocomposite for Performance Enhancement of Optical Fiber Bragg Grating Temperature Sensor

Polyurethane-graphene (PU-graphene) nanocomposite was utilized as the sensing material for a fiber Bragg grating (FBG) temperature sensor. The nanocomposite was characterized using a Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS) to study the morphology and physical properties of the materials for FBG temperature sensing application. The physical, chemical, and conductivity of PU-graphene improve after graphene was introduced in pristine PU. The FTIR shows that the strong intermolecular interaction between–O–C = O (ester) and hydrogen in graphene in the PU-graphene was indicated by the shift to lower wavenumber of ether (C–O–C) peak at ~1220 cm−1 to ~1218 cm−1. TGA shows the thermal stability of PU increases to 217 °C due to the strong intermolecular interaction with the presence of graphene flakes. EIS shows a good electrical conductivity of $1.39\times 10^{-9}$ Scm−1 in the PU-graphene due to the electron transfer provided by the graphene. The SEM shows a rough and uneven texture on the surface of FBG coated by PU-graphene nanocomposite which shows that the graphene flakes are completely coated by polyurethane polymer. The PU-graphene was then dip-coated on the optical fiber-based Bragg grating, and the sensor performance for a temperature sensor was evaluated, where a good linearity with the sensitivity of 6 pm/°C was achieved.

Surface, thermal and hemocompatible properties of novel single stage electrospun nanocomposites comprising polyurethane blended with bio oilTM.

In this work, the physicochemical and blood compatibility properties of prepared PU/Bio oil nanocomposites were investigated. Scanning electron microscope (SEM) studies revealed the reduction of mean fiber diameter (709 ± 211 nm) compared to the pristine PU (969 nm ± 217 nm). Fourier transform infrared spectroscopy (FTIR) analysis exposed the characteristic peaks of pristine PU. Composite peak intensities were decreased insinuating the interaction of the bio oilTM with the PU. Contact angle analysis portrayed the hydrophobic nature of the fabricated patch compared to pristine PU. Thermal gravimetric analysis (TGA) depicted the better thermal stability of the novel nanocomposite patch and its different thermal behavior in contrast with the pristine PU. Atomic force microscopy (AFM) analysis revealed the increase in the surface roughness of the composite patch. Activated partial thromboplastin time (APTT) and prothrombin time (PT) signified the novel nanocomposite patch ability in reducing the thrombogenicity and promoting the anticoagulant nature. Finally the hemolytic percentage of the fabricated composite was in the acceptable range revealing its safety and compatibility with the red blood cells. To reinstate, the fabricated patch renders promising physicochemical and blood compatible nature making it a new putative candidate for wound healing application.