Type Of Polyol Research Articles

Polyol Reduction: A Low-Temperature Eco-Friendly Solution Process for p-Channel Copper Oxide-Based Transistors and Inverter Circuits.

An optimized polyol reduction method was proposed for p-type CuxO deposition using a spin-coating method at low temperatures. The film characterizations and the electrical properties of integrated thin-film transistors (TFTs) were investigated as a function of annealing temperature and polyol type. The CuxO TFTs derived from propylene glycol showed the optimal performance with an average field-effect hole mobility of 0.15 cm2 V-1 s-1, an on/off current ratio of ∼104, and a threshold voltage of -7 V at a low temperature of 220 °C. Considering few investigations on the operational/air stability of solution-processed p-type oxide TFTs, we carried out systematical studies and revealed different roles of O2 and H2O on the device performance. The low activation energy (0.16 eV) for hole transport and high voltage gain (37) of the composed complementary inverter highlight great potential for the construction of all oxide-based transparent flexible electronics and circuits.

Catalytic conversion of biomass-derived polyols into para-xylene over SiO2-modified zeolites

This work proved that biomass-based polyols (sorbitol, xylitol, erythritol, glycerol and ethanediol) were able to be converted into high-value chemical (p-xylene) by catalytic cracking of polyols, alkylation of aromatics, and the isomerization of xylenes over the SiO2-modified zeolites. Compared to the conventional HZSM-5 zeolite, the SiO2-containing zeolites considerably increased the selectivity and yield of p-xylene due to the reduction of external surface acidity and the narrowing of pore entrance. The influences of the methanol additive, reaction temperature, and types of polyols on the selectivity and yield of p-xylene were investigated in detail. Catalytic cracking of polyols with methanol significantly enhanced the production of p-xylene by the alkylation of toluene with methanol. The highest p-xylene yield of 10.9 C-mol% with a p-xylene/xylenes ratio of 91.1% was obtained over the 15wt%SiO2/HZSM-5 catalyst. The reaction pathway for the formation of p-xylene was addressed according to the study of the key reactions and the characterization of catalysts.

Wound dressing application of castor oil- and CAPA-based polyurethane membranes

The objective of this study was to investigate and compare the effects of two different types of polyols on properties of synthesized polyurethanes (PUs), to develop biomedical applications of these materials. Polyurethane membranes were prepared from two different polyols (castor oil and CAPA 7201) as wound healing films. The chemical, physical, mechanical and biological properties of the prepared membranes were studied. Both films had smooth surfaces, with no signs of pores and cracks. CAPA-based polyurethane showed higher crystallinity and lower thermal stability compared to the other polyurethanes. Results of contact angle and water vapor transmission rate (WVTR) showed no significant differences between two different polyols used in PU synthesis. The water absorption of the CAPA-based PU (5.67%) was higher than the castor oil-based PU (0.76%) after immersion in water for 3 days at 37 °C. The values of WVTR were obtained as 260 and 285 g/m2/day for PCL and castor oil-based PUs, respectively. CAPA-based PU membrane showed 4 MPa tensile strength and about 550% elongation at break which is higher than the other samples (1.7 MPa and 100%). The viability of L-929 mouse cell line in contact with CAPA-based PU film was greater than 80% and showed a lack of toxicity of the synthesized polymer. The in vivo wound healing model evaluation using a full-thickness rat model experiment was carried out within 13 days. The wound size reduction of castor oil and CAPA-based PUs reached to 99% compared to 68% in gauze sample on the 13th day after surgery. The in vivo results revealed that PUs derived from CAPA 7201 was milder and led to less inflammatory response compared to castor oil which consequently was completely filled with new epithelium without any significant adverse reactions. Consequently, results confirmed the potential use of CAPA-based PU in biomedical field.

Influence of Chemical Structure of Petrochemical Polyol on Properties of Bio-polyurethane Foams

In this study, the influence of the chemical structures of petrochemical polyols on the foaming process of polyurethane compositions as well as on selected properties of the foams obtained has been investigated. Two types of petrochemical polyols were used—polyester and polyether polyols as well as their blends with a rapeseed oil-based polyol. Dielectric polarization, temperature and expansion velocity were determined during the foaming process of the polyurethane systems with different polyol components. The results show the highest reactivity of the polyester polyol and a decrease of the polyurethane system’s reactivity as a result of a partial replacement of the petrochemical polyol with the bio-based polyol. The content of the closed cells in the materials obtained strongly depends on the petrochemical polyol used. The results indicate that the chemical structure of the petrochemical polyol had a significant effect on the cellular structure as well as the physical–mechanical properties of the final products. A significant worsening of the foams’ mechanical properties was observed as an effect of a partial replacement of the polyester polyol with the rapeseed oil-based polyol. In contrast, a partial replacement of the polyether polyol caused an improvement of the cell structure keeping the mechanical properties of the modified foams at the same level.

Metal–organic framework (UiO‐66)‐dispersed polyurethane composite films for the decontamination of methyl paraoxon

AbstractPolyurethane (PU) composite films containing UiO‐66 were prepared for the decontamination of methyl paraoxon (MPO), an organophosphate‐type nerve agent simulant. Waterborne PU dispersions were synthesized by changing the type of polyol to improve the miscibility with UiO‐66. Depending on the size of the polyol, the PU films had different surface free energy, flexibility and compatibility with UiO‐66. UiO‐66 was well dispersed in PU films when the flexibility of the films increased. The tensile strength of the UiO‐66/PU composite films gradually increased from 7.5 to 11.3 MPa with increasing UiO‐66 content, but the elongation decreased from 781 to 120%. The decomposition of MPO by the UiO‐66/PU composite films increased with an increase of the UiO‐66 content and hydrolysis time. In the case of the 21.2 wt% UiO‐66/PU composite film, 48% of MPO was decomposed within 3 h. This was similar to the decomposition when using a UiO‐66 slurry (52%) under the same decomposition conditions. Unlike the UiO‐66 slurry, the 21.2 wt% UiO‐66/PU composite film maintained a similar MPO decomposition performance after 10 repeated experiments. © 2019 Society of Chemical Industry

How the soft segment arrangement influences the microphase separation kinetics and mechanical properties of polyurethane block polymers

In this work, morphological, phase transitions, microphase separation, hydrogen bonding, rheological and mechanical properties of novel thermoplastic polyurethane elastomers (TPUs) consisting of polytetrahydrofuran/ polycaprolactone (PTHF/PCL) as soft segments with different soft segment arrangements were discussed. Change in sequence of feeding as a reliable method for controlling soft segment arrangements was developed. Successful synthesizing of the TPUs was evaluated by ATR-FTIR and 13C NMR spectroscopy. AFM images indicated that the change in soft segment arrangements of TPUs with same molar ratio of ingredients led to different hard segment aggregations morphology. Time sweep experiment showed that the storage modulus evolution at 125 °C is different with 140 °C, and kinetics and extent of microphase separation was systematically found to reduce with increasing temperature. Isothermal and non-isothermal examinations have shown that using PCL and PTHF in the main chain accelerates the microphase separation process comparing sample with blend of polyurethanes containing one type of polyols. Mechanical property data indicated that the extreme enhanced elongation at break and toughness of TPU with random soft segment arrangements of PTHF/PCL is highest in comparison with other samples.

Preparation of niobium-based oxygen carriers by polyol-mediated process and application to chemical-looping reforming

New niobium-based oxygen carriers were prepared adopting polyol-mediated process. Four different polyols were used (diethylene glycol, triethylene glycol, tetraethylene glycol, and 1,2-propanediol) and four different quantities of water (0 mL, 1 mL, 10 mL, 30 mL, with a total volume of 80 mL of solution). Series of bulk and alumina-supported materials were prepared. Different structural and textural properties were obtained, depending on polyol type and hydrolysis ratio. After thermal treatment at 1000 °C, alumina-supported materials were evaluated in a lab-scaled fixed bed reactor. Despite a low conversion of methane due to a low content of active phase AlNbO4, they presented a high selectivity to syngas (a mixture of H2 and CO) during the first few seconds of reaction with CH4, indicating a high selectivity towards chemical-looping reforming process.

Castor oil-derived water-based polyurethane coatings: Structure manipulation for property enhancement

Water-based polyurethane coatings give a soft feeling for surface engineering for advanced wear- and friction-resisted purposes. In this work, we synthesized three types of polyols from castor oil applying short- and high-efficiency method for potential soft coating uses, as an appropriate alternative for methods that use a rotary evaporation and a vacuum oven in polyol synthesis. Castor oil was epoxidized in the presence of two types of catalysts, i.e. γ-alumina (ECOAl) and formic acid (ECOF). Although we could not detect unwelcome reactions taking place in the reaction chamber that should reduce the content of oxirane oxygen, the relative percentages of double bond conversion to oxiran for ECOAl and ECOF were theoretically 96% and 74%, respectively. Ring opening reaction of ECOAl was performed by two types of saponified castor oil utilizing Dean–Stark trap, an appropriate alternative for methods that use a rotary evaporation and a vacuum oven in polyol synthesis. The synthesized polyols were characterized by FTIR (ATR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), viscometer and OH number evaluation. Different weight percentages of the polyol samples having Tg values of ca. -6.5 °C and OH number of 6.2 were applied in synthesis of water-based polyurethane (WPU). It was found that WPU with 40 wt.% polyol has a minimum particle size and minimum poly dispersity index. WPU with 60 wt.% polyol exhibited the highest molecular weight, while it had the lowest viscosity, water absorption, glossiness, hardness, adhesion and Tg. By such structural manipulations we provided a basis for enhancement of properties of coatings for future works.

Gaseous and speciated particulate emissions from the open burning of wastes from tree pruning

Open-air burning of wastes from tree pruning is a common practice in many regions worldwide. However, this practice degrades air quality and contributes to the greenhouse effect. Aiming at characterizing particle (PM10) and gaseous emissions, the smoke from the open burning of vine, olive, willow and acacia branches was sampled and then analyzed by multiple techniques. Emission factors of gaseous compounds were as follows (g kg−1 biofuel, dry basis): 1564–1663 CO2, 40.6–87.7 CO, 2.06–5.82 CH4, 0.91–3.73 ethane, <0.99 ethylene, and <1.80 formaldehyde. PM10, organic carbon (OC) and elemental carbon (EC) emissions were in the ranges 8.76–20.1, 2.70–7.44, and 0.32–1.18 g kg−1 biofuel, dry basis, respectively. From the PM10 emitted, water soluble ions represented from 5.3% (vines) to 13.6% (acacia). Potassium was the dominant ionic species, accounting for a PM10 content from 1.4 to 4.7% wt. While in smoke from vines and olive combustion the NaCl mass fractions were lower than 0.9%, higher weight percentages were obtained for willow (3.6) and acacia (6.7). On average, OC accounted for PM10 mass fractions of 33.4, 19.3, 32.3 and 36.5%, while EC represented 5.04, 2.34, 3.53 and 7.32% for willow, acacia, vines and olive combustion, respectively. Emissions of polycyclic aromatic hydrocarbons (PAHs) from the combustion of vines and olive branches were one order of magnitude higher than those from acacia and willow. Mean levoglucosan mass fractions of 18.1, 13.2, 17.1 and 12.4 mg g−1 PM10 were obtained in samples from the combustion of vines, olive, willow and acacia, respectively. Smoke particles also encompassed several other polar constituents, such as various types of acids, phenolic compounds, sterols, and polyols, whose contribution to the PM10 mass varied with the biofuel burned.

A simple and versatile method to tailor physicochemical properties of thermoplastic polyurethane elastomers by using novel mixed soft segments

Novel thermoplastic polyurethane elastomers (TPUs) were designed and synthesized using mixtures of poly (tetramethylene ether) glycol (PTMG) and polycaprolactone (PCL) diols as soft segments. Five block polyurethanes with different soft segment composition were studied in order to discover the impact of mixed soft segments on the properties of TPUs. The corresponding properties of these polyurethanes including phase transitions, morphology, microphase separation, hydrogen bonding, rheological and mechanical were investigated by experimental methods. Molecular dynamics simulation was also used to evaluate dynamic of hard and soft segments, hydrogen bonding and segmental interactions at atomic level. Successful synthesizing of the TPUs was evaluated by ATR-FTIR and 13C NMR spectroscopy. The results indicated that polyurethanes with higher PTMG content produce stronger hydrogen bonding, more solid like behavior, higher microphase separation and lower viscosity than polyurethanes with high PCL diol; however the most exciting outcome is the influence that mixed soft segments have on the microphase separation kinetics and mechanical properties. Isothermal and non-isothermal examinations have shown that using mixed soft segments accelerated the microphase separation process comparing samples with one type of polyols and sample containing equal compositions of each polyols has the fastest microphase separation kinetics. Microscopy images showed that this sample has the thread-like hard segment rich regions and its morphology differs from other samples. Mechanical property data indicated that the enhanced elongation at break and overall toughness of TPU at equal ratio of PCL/PTMG is highest in comparison with other samples.

A novel investigation on micro-phase separation of thermoplastic polyurethanes: simulation, theoretical, and experimental approaches

Thermoplastic polyurethanes (TPUs) based on soft segments with varying molecular weight and molecular architecture show interesting micro-phase separation, thermal, morphological, molecular dynamics, and rheological properties. In the present study, TPUs based on two types of polyols, i.e., poly(tetramethylene ether) (1000 and 2000 g/mol) and polycaprolactone (500 and 2000 g/mol), were synthesized. This work has aimed to combine synthetic procedures, physical–chemistry calculations, and molecular dynamics simulation to study the effect of structure and molecular weight of the soft segments on TPU properties. Extent and kinetics of micro-phase separation were quantified with several methods such as spectroscopy, time-sweep rheological analysis, product of interaction parameter and degree of polymerization (χN), thermal analysis, compressible regular solution model, molecular dynamics, and microscopy. The results showed that high molecular weight polyether- and low molecular weight polyester-based synthesized TPUs have the highest and the lowest micro-phase separations, respectively. Moreover, in each class of polyol, the degree of micro-phase separation was concurrently increased with soft-segment block length. However, competition between enthalpic and entropic factors in the study of the polyols led to different results by various methods. Moreover, from the mechanical properties viewpoint, ester-based TPUs showed higher Young’s modulus and lower elongation-at-break compared to ether-based counterparts.

Morphological changes of calcium hexaboride powder synthesized from condensed boric acid-polyol product

We previously reported a novel low-temperature synthesis method for calcium hexaboride (CaB6) powder via the transient formation of boron carbide (B4C) using a condensed boric acid (H3BO3)-polyol product. In this study, the effect of the type of polyol on the morphology of the CaB6 powder was investigated. Three types of polyol, glycerin, mannitol, and poly(vinyl alcohol) (PVA), were used for the preparation of condensed H3BO3-polyol products since the B4C particles prepared from these polyols exhibit different morphologies. CaB6 powder was successfully synthesized at a low temperature of 1400 °C regardless of the polyol used. The size of the obtained CaB6 particles varied with the polyol used, which reflected the size of the B4C particles prepared using the corresponding polyol. These results indicate that the morphology of the obtained CaB6 powder is derived from that of the transiently formed B4C particles.

Candidate Polyurethanes Based on Castor Oil (Ricinus communis), with Polycaprolactone Diol and Chitosan Additions, for Use in Biomedical Applications.

Polyurethanes are widely used in the development of medical devices due to their biocompatibility, degradability, non-toxicity and chemical versatility. Polyurethanes were obtained from polyols derived from castor oil, and isophorone diisocyanate, with the incorporation of polycaprolactone-diol (15% w/w) and chitosan (3% w/w). The objective of this research was to evaluate the effect of the type of polyol and the incorporation of polycaprolactone-diol and chitosan on the mechanical and biological properties of the polyurethanes to identify the optimal ones for applications such as wound dressings or tissue engineering. Polyurethanes were characterized by stress-strain, contact angle by sessile drop method, thermogravimetric analysis, differential scanning calorimetry, water uptake and in vitro degradation by enzymatic processes. In vitro biological properties were evaluated by a 24 h cytotoxicity test using the colorimetric assay MTT and the LIVE/DEAD kit with cell line L-929 (mouse embryonic fibroblasts). In vitro evaluation of the possible inflammatory effect of polyurethane-based materials was evaluated by means of the expression of anti-inflammatory and proinflammatory cytokines expressed in a cellular model such as THP-1 cells by means of the MILLIPLEX® MAP kit. The modification of polyols derived from castor oil increases the mechanical properties of interest for a wide range of applications. The polyurethanes evaluated did not generate a cytotoxic effect on the evaluated cell line. The assessed polyurethanes are suggested as possible candidate biomaterials for wound dressings due to their improved mechanical properties and biocompatibility.

The Effect of Polyol Types and Molecular Weight on the Shape Memory Properties of Palm Kernel Oil – based Polyurethane

Abstract The main objective of this study was to investigate the effect of different types and molecular weight (MW) of polyol on the shape memory properties of palm kernel oil–based shape memory polyurethane (SMPU) prepared by two step bulk polymerization procedure. Poly(ethylene glycol) (PEG) and poly(e-caprolactone) (PCL) with MW 2000 and MW 4000 were used as the main material for soft segment. The addition of palm kernel oil polyol (PKO-p) in the SMPU system is due to the concern of the renewable resources. Shape fixity and shape recovery properties were investigated using bending test to evaluate the shape memory effect. The results indicate that the shape fixity of SMPU depends primarily on the types of polyol whereas MW had a slight effect towards the shape fixity. SMPU synthesized from PEG with MW 2000 performed a good shape fixity, about 96% compared to that of PCL with MW 2000, about 29%. In the case of PCL – based SMPU, the increase of shape fixity is proportional to the increase of MW. All samples, except the one based on PEG4000, exhibited excellent shape recovery (100%).

Development of polyurethane foam dressing containing silver and asiaticoside for healing of dermal wound

Polyurethane foam dressings for dermal wounds were formulated with natural polyols in order to improve the foam characteristics and the release of 2 active agents, silver and asiaticoside (AS) as an antimicrobial agent and an herbal wound healing agent, respectively. The foam was instantly formed by interaction of polyols and diisocyanate. Hydroxypropyl methylcellulose, chitosan and sodium alginate were individually mixed with the main polyols, polypropylene glycol, in the formulation while the active components were impregnated into the obtained foam dressing sheets. Although the type and amount of the natural polyols slightly affected the pore size, water sorption-desorption profile and compression strength of the obtained foam sheets, a prominent effect was found in the release of both active components. Among natural polyols formulations, foam sheets with alginate showed the highest silver and AS release. Non-cytotoxicity of these foam sheets to human fibroblast cells was confirmed. Antimicrobial testing on four bacteria strains showed that 1 mg/cm2 silver in formulations with 6% of natural polyols and without natural polyols had sufficient content of the silver release with comparable inhibition zone and significantly larger zone than other formulations. In pig study, the foam dressing with 6% alginate, 1 mg/cm2 silver and 5% AS could improve wound healing in both the percentage of the wound closure and histological parameters of the dermal wound without any dermatologic reactions. In conclusion, this innovative foam dressing had potential to be a good candidate for wound treatment.

Synthesis of Polyurethane Elastomers by One-shot Technique and Study of Different Polyol Types and Hard Segment Content After Exposure to γ-Irradiation

Synthesis of Polyurethane Elastomers by One-shot Technique and Study of Different Polyol Types and Hard Segment Content After Exposure to γ-Irradiation

Alumina-supported Cu(II), Co(II), and Fe(II) complexes as catalyst for esterification of biomass-derived levulinic acid with trimethylolpropane (TMP) and pentaerythritol (PE) and upgrading via hydrogenation

A polyol-based ester was synthesized from biomass-derived bio-oil for application as a biolubricant. The bio-ester is biodegradable, non-toxic, and does not require mineral oil usage. Levulinic acid (LA), a major component obtained from bio-oil, was used for the catalytic esterification with two types of polyols, i.e., trimethylolpropane (TMP) and pentaerythritol (PE), in the presence of alumina-supported Cu(II), Co(II), and Fe(II) complexes as catalysts. Alumina-supported Cu(II), Co(II), and Fe(II) complexes [Cu(Tyr)(GA)]Cl-alumina, [Co(Tyr)(Amp)]Cl-alumina, and [Fe(Tyr)(Amp)]Cl-alumina were synthesized by the reaction of ligands [L-tyrosine (Tyr), Gallic acid (GA), and 2-aminopyridine (Amp)] with metal chloride salts. The catalysts were characterized by elemental analyses (CHN), magnetic susceptibility, Fourier transform infrared spectroscopy (FTIR), thermo-gravimetric analysis/differential thermal analysis (TGA/DTA), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) techniques. Catalytic performances of the synthesized complexes were investigated via esterification of levulinic acid with trimethylolpropane and pentaerythritol. In addition, the two best catalysts, [Cu(Tyr)(GA)]Cl and [Co(Tyr)(Amp)]Cl-alumina, were further employed for the in situ hydrogenation of levulinate esters at 120 °C to 130 °C and 7 bar to 8 bar H2 pressure for upgrading in a specially designed reactor. The alumina-supported catalysts were active, reusable, and exhibited their efficiency as heterogeneous catalysts for esterification and hydrogenation reactions for synthesizing ester-based oils.

Mixed polyols synthesis of high aspect ratio silver nanowires for transparent conductive films

Silver nanowires (AgNWs) with high aspect ratio were rapidly synthesized by a mixed polyols process by adding diethylene glycol, triethylene glycol and glycerol into the ethylene glycol to construct the mixed polyols respectively, and the effects of type and volume fraction of mixed polyols on the morphology and aspect ratio of AgNWs were investigated in detail, and the optoelectrical properties of the corresponding transparent conductive electrodes were briefly introduced. The presence of mixed polyols can increase the viscosity of the solution, reduce the migration rate of Ag+ and nuclear in the solution, decrease the diameter of silver nanowires and heighten the length and aspect ratio. Appropriate mixed polyols (triethylene glycol) with the volume fraction of 30% allows the rapid synthesis of AgNWs with the diameter of about 64.2 nm, the length of 66.0 μm and the aspect ratio as high as 1029. The as-prepared AgNWs films possess a transmittance of 89.8% and a sheet resistance of 4.56 Ω/sq. The resultant AgNWs with high aspect ratio can be applied to prepare transparent conductive films.

Ultrasound assisted miniemulsion polymerization to prepare poly(urea-urethane) nanoparticles

Abstract Recently, the physical and chemical effects of ultrasound in polymeric materials synthesis have attracted great attention. This work presents the synthesis of novel polymeric materials by polymerization of isophorone diisocyanate with different polyols. Polymers were synthesized by step miniemulsion polymerizations, using ultrasound bath and thermostatic bath. The effects of ultrasound, temperature and polyol type were evaluated by Fourier transform infrared spectroscopy, gel permeation chromatography, dynamic light scattering and titrimetry. Polymerization under ultrasound bath showed that different reaction temperatures in the range between 50 °C and 80 °C directly influence the molecular weight of the polymers, urea/urethane formation and increase of diisocyanate consumption rate. In addition, different polyols used in polymerizations in miniemulsion had a significant effect on the characteristics of the resulting poly(urea-urethane) nanoparticles. Finally, ultrasound assisted polymerizations showed a faster diisocyanate consumption rate, but did not lead to enhanced molecular weights.

A macroscopically nondestructive method for characterizing surface mechanical properties of polymeric coatings under accelerated weathering

The surface of coatings and plastics is the first target in any degradation process initiated by ultraviolet (UV) radiation or mechanical stress (via scratch and abrasion). Surface damage can lead to changes in optical, morphological, and mechanical properties and can result in pathways for ingress of moisture and corrosive agents. Current test methods for monitoring performance of protective coatings focus on chemical properties and optical properties, such as color and gloss measurements, or invasive tests such as abrasion and cross-cut adhesion. In this study, a macroscopically nondestructive performance protocol using nanoindentation metrology via a well-controlled scratch test was applied to evaluate the scratch resistance and monitor the surface mechanical property changes in a protective coating under accelerated weathering. Polyurethane (PU) coatings with different polyol compositions were chosen for this study. Coating specimens were exposed to high-intensity UV radiation at 55°C and 75% RH conditions. Exposed specimens were removed at specified UV exposure times for surface modulus/hardness and scratch resistance characterization via nanoindentation and scratch test. The effect of polyol type and UV radiation dose on the scratch damage (scratch morphology) was investigated and correlated with the surface hardness and modulus of the materials.