Urethane Amide Research Articles

Removal of Dye Using Lignin-Based Biochar/Poly(ester amide urethane) Nanocomposites from Contaminated Wastewater

Removal of Dye Using Lignin-Based Biochar/Poly(ester amide urethane) Nanocomposites from Contaminated Wastewater

Poly(ester amide urethane) as robust material

Poly(ester amide urethane) as robust material

Elastomeric biodegradable poly(ester amide urethane) as a tough and robust material

Poly(ester amide)s belong to a special class of polymers and their intrinsic properties can be tailored by tuning their chemical structures. In this regard, poly(ester amide urethane) resins were synthesized to circumvent the shortcomings as well as to impart new features into the poly(ester amide) framework. In the present work, various compositions of poly(ester amide urethane) were prepared by varying the proportions of isophorone diisocyanate. The structural analysis of the synthesized polymeric material was accomplished using various techniques viz., FTIR, XPS, PXRD, etc. On investigating the mechanical profile study, it was noted that the polymeric specimens exhibited excellent elongation at break values ranging from 640.81 % to 1875.91 %, thereby rendering traits of a sturdy elastomeric material. The samples also demonstrated outstanding toughness values from 1125.11 MJm−3 to 1895.62 MJm−3. In turn, the polymeric material displayed satisfactory thermal stability above 200 °C along with good chemical resistance values. Disparate aging tests were conducted to assess the durability of the material under stringent environmental conditions. The materials demonstrated remarkable enhancement in tensile strength parameters upon exposure to various aging regimes (heat, UV, etc.) which further promote their utility as robust materials for outdoor applications. Additionally, they revealed exceptionally good biodegradable attributes along with significant cytocompatibility behavior.

Canola Oil based Poly(ester–ether–amide–urethane) Nanocomposite and Its Anti-Corrosive Coatings

The environmental and health hazards associated with petro-based chemicals have motivated the researchers to replace them partially or wholly with renewable resource-based polymers. Vegetable oils serve as an excellent alternative to this end as they are cost effective, eco-friendly, easily available and rich with functional groups amenable to chemical reactions. The aim of the research work is to prepare Canola oil [CANO] derived poly (ester–ether–amide–urethane) (CPEEUA) nanocomposite coating material using N,N-bis (2-hydroxyethyl) fatty amide [CFA] obtained from CANO, Lactic acid [LA], and reinforced with Fumed Silica [FS]. CPEEUA was obtained by esterification, etherification, and urethanation reactions and its structure was confirmed from FTIR and NMR spectral analyses. CPEEUA/FS coatings were found to be scratch resistant, flexible, well-adhered to mild steel panels, and hydrophobic with 2.0–2.5 kg scratch hardness, 150lb/inch impact resistance and >90° contact angle value. They exhibited good corrosion protection in 3.5 wt% NaCl solution as investigated by Potentiodynamic Polarization and Electrochemical Impedance tests. CPEEUA coatings are safe for usage up to 200 °C.

Towards bio-upcycling of polyethylene terephthalate

Over 359 million tons of plastics were produced worldwide in 2018, with significant growth expected in the near future, resulting in the global challenge of end-of-life management. The recent identification of enzymes that degrade plastics previously considered non-biodegradable opens up opportunities to steer the plastic recycling industry into the realm of biotechnology.Here, the sequential conversion of post-consumer polyethylene terephthalate (PET) into two types of bioplastics is presented: a medium chain-length polyhydroxyalkanoate (PHA) and a novel bio-based poly(amide urethane) (bio-PU). PET films are hydrolyzed by a thermostable polyester hydrolase yielding highly pure terephthalate and ethylene glycol. The obtained hydrolysate is used directly as a feedstock for a terephthalate-degrading Pseudomonas umsongensis GO16, also evolved to efficiently metabolize ethylene glycol, to produce PHA. The strain is further modified to secrete hydroxyalkanoyloxy-alkanoates (HAAs), which are used as monomers for the chemo-catalytic synthesis of bio-PU. In short, a novel value-chain for PET upcycling is shown that circumvents the costly purification of PET monomers, adding technological flexibility to the global challenge of end-of-life management of plastics.

Upcycling of hydrolyzed PET by microbial conversion to a fatty acid derivative.

The enzymatic degradation of polyethylene terephthalate (PET) results in a hydrolysate consisting almost exclusively of its two monomers, ethylene glycol and terephthalate. To biologically valorize the PET hydrolysate, microbial upcycling into high-value products is proposed. Fatty acid derivatives hydroxyalkanoyloxy alkanoates (HAAs) represent such valuable target molecules. HAAs exhibit surface-active properties and can be exploited in the catalytical conversion to drop-in biofuels as well as in the polymerization to bio-based poly(amide urethane). This chapter presents the genetic engineering methods of pseudomonads for the metabolization of PET monomers and the biosynthesis of HAAs with detailed protocols concerning product purification.

STUDY ON MOISTURE-CUR ED POLYURETHANE AS UNDERCOATING LAYER FOR METALLIZATION

In this work a technique of metallizing substrate via electroless plating using moisture-cured polyurethane (MCPU) system as the undercoat is presented. MCPU prepolymer was prepared by mixing polyethylene glycol divinyl ether and diphenylmethane-4, 4’-diisocyanate in 1:1 ratio. The effects of etching time as well as curing period on the surface characteristic of MCPU undercoating were investigated. Contact angle measurements, FTIR and SEM were employed to study the changes on the surface of the treated MCPU undercoatsprior to electroless nickel plating. Electroless plating was performed using nickel bath and visual inspection was performed after completing the electroless plating cycles. Relative increase in wettability of the treated MCPU was observed. The surface became hydrophilic after subjecting to mild etching for 1 minute. SEM analysis revealed different pitted structures on the treated MCPU that were cured at different periods. FTIR analysis of the treated MCPU showed some chemical changes marked by the presence of free hydroxyl group and decrease of CH (methylene), urethane C=O, urethane amide and ether peaks. FTIR also showed the sign of further NCO reaction, which indicates by the decrease of NCO peak and increase of NH and urea C=O peaks. The standard pull-off testing method (ASTM D 4541) was employed to evaluate the adhesion strength of nickel deposits coated on MCPU undercoating layer.The test results revealed that curing period and etching time influence the adhesion performance.The results also show that at a selected curing period, prolong etching time will decrease the adhesion strength. Meanwhile prolong curing period will improve the adhesion strength.

Waterborne hyperbranched poly(ester amide urethane) thermoset: Mechanical, thermal and biodegradation behaviors

Renewable resource based waterborne hyperbranched poly(ester amide urethane)s (WHPEAU) with varying compositions were synthesized by reacting polyamide polyol of diethanol amine, caprolactam and citric acid with dimer acid, phthalic anhydride and isophorone diisocyanate via a catalyst and solvent free facile route. The parent poly(ester amide) was obtained by using the same technique and reactants except isophorone isocyanate. The chemical structures of the prepared polymers were characterized by NMR and FTIR spectral analyses. The thermosets of these polymers were obtained by chemical crosslinking with commercially available epoxy and fatty acid modified poly(amido amine) hardener. These thermosets showed high mechanical properties like tensile strength (7.5 MPa against 3 MPa) and toughness (14.48 MJm−3 against 6 MJm−3) without much losing the elongation at break (174% against 286%) over the poly(ester amide) thermoset. Further, chemical resistance of the thermosets in different chemical media was found to be better than the poly(ester amide) thermoset. Most interestingly, the accelerated bacterial biodegradability using bacterial strain like Pseudomonas Auregonisa (P. Auregonisa) revealed almost comparable biodegradability to the poly(ester amide) thermoset. The WHPEAU thermosets, thus, not only exhibited high performance but they also possess required attributes to be used as environmentally benign polymeric material.

Biodegradable gadolinium-chelated cationic poly(urethane amide) copolymers for gene transfection and magnetic resonance imaging

Theranostic nano-polyplexes containing gene and imaging agents hold a great promise for tumor diagnosis and therapy. In this work, we develop a group of new gadolinium (Gd)-chelated cationic poly(urethane amide)s for gene delivery and T1-weighted magnetic resonance (MR) imaging. Cationic poly(urethane amide)s (denoted as CPUAs) having multiple disulfide bonds, urethane and amide linkages were synthesized by stepwise polycondensation reaction between 1,4-bis(3-aminopropyl)piperazine and a mixture of di(4-nitrophenyl)-2, 2′-dithiodiethanocarbonate (DTDE-PNC) and diethylenetriaminepentaacetic acid (DTPA) dianhydride at varied molar ratios. Then, Gd-chelated CPUAs (denoted as GdCPUAs) were produced by chelating Gd(III) ions with DTPA residues of CPUAs. These GdCPUAs could condense gene into nanosized and positively-charged polyplexes in a physiological condition and, however, liberated gene in an intracellular reductive environment. In vitro transfection experiments revealed that the GdCPUA at a DTDE-PNC/DTPA residue molar ratio of 85/15 induced the highest transfection efficiency in different cancer cells. This efficiency was higher than that yielded with 25kDa branched polyethylenimine as a positive control. GdCPUAs and their polyplexes exhibited low cytotoxicity when an optimal transfection activity was detected. Moreover, GdCPUAs may serve as contrast agents for T1-weighted magnetic resonance imaging. The results of this work indicate that biodegradable Gd-chelated cationic poly(urethane amide) copolymers have high potential for tumor theranostics.

Two-component dendritic gel: Influence of the aromatic chain length on the organogel stability and supramolecular architecture

Abstract we report the influence of the aromatic chain length on the organogel stability and supramolecular structure. First, we designed and readily prepared a two-component dendritic gelator based on a combination of a third-generation poly(urethane amide) dendron and a rigid aromatic spacer chain ( e.g. , 1,4-diazine, 4,4′-dipyridy, 1,4-bis(pyrid-4-yl)benzene, 4,4-di(4-pyridyl)biphenyl) in 2:1 molar ratio. All two-component gelators were easy to gelate aromatic solvents, especially toluene and p -xylene. When the length of aromatic spacer chain was increased, the gel-to-solution transition temperature first increased, and then decreased. The supramolecular structures and morphologies in xerogel samples of gelators have been carefully studied using the transmission electron microscopy and the atomic force microscopy characterizations. We demonstrated that the stability and supramolecular structures of organogels could be well controlled and regulated by simple length regulation of the aromatic spacer chain in two-component gelator, and thus we believe that applying this kind of method will provide significant new insights for the fabrication of soft materials for various applications.

Impressive Transmission Mode Electromagnetic Interference Shielding Parameters of Graphene-like Nanocarbon/Polyurethane Nanocomposites for Short Range Tracking Countermeasures.

Shielding the microwave signature (8.2-12.4 GHz, X-band) of a locked in target is a tactically important electronic countermeasure. Herein, we report on mitigation in X-band transmission mode shielding parameters for polyurethane (PU), after incorporating graphene-like nanocarbon sheets (GNCs). Initially, PU and variable weight percent (1-25) GNCs/PU paste samples were subjected to Fourier transform infrared, Raman spectroscopy, and scanning electron microscopy. These samples were molded into toroidal shaped specimens by adiabatic hot-pressing technique, for microwave scattering measurements. Parameters, such as complex permittivity (ϵ'-jϵ″), alternating current (ac) conductivity, skin thickness, transmission (S21), effective transmission loss (SET), and shielding effectiveness were determined, in addition to direct current (dc) conductivity. The real and imaginary components are increased, respectively, by ∼5 and ∼30 times, whereas loss tangent, by ∼7, at 25 wt % loading of GNCs. The ac conductivity is enhanced from 0.248 (PU) to 7.288 S/m (25 wt %) by maximizing transmission loss to -26.45 dB (99.9%) and minimizing thickness to 1-2 mm. The dc percolation threshold is found to be low at ∼5 wt %, indicating superior dispersibility of GNCs, thereafter. In analysis, the atomic polarization (at ∼10 GHz) associated with the aromatic urethane amide rings acts as a backbone to engage incident electromagnetic field wiggles. The coupling occurs via charge transfer polarization currents at doubly bonded nitrogen, oxygen, and hydrosorpted sp3 carbon sites in GNCs. The field-matter interaction is dominant at the microvoid skin interface between GNCs and PU. Possible polarization mechanism is explained. The GNCs/PU nanocomposites are realized as an effective electromagnetic interference shielding block in the tracking band. The details are presented.

Synthesis and characterization of aliphatic poly(amide urethane)s having different nylon 6 segments through non-isocyanate route

Two nylon-6 oligomers having polymerization degrees of 4.99 and 3.55 terminated with H2N– and HO– groups (H2N-PA-OHs) were prepared by the ring-opening polymerization of caprolactam with ethanolamine at different molar ratios. These oligomers were transformed into HO–terminated nylon-6 oligomers (HO-PA-OHs) through reaction with excessive caprolactone. The transurethane polycondensation of HO-PA-OHs with a diurethanediol, i.e., 1,6-bis(hydroxyethyloxy carbonyl amino)hexane (BHCH), was carried out at 170 °C under normal pressure for 4 h and at 180 °C under a reduced pressure of 3 mmHg for 6.5 h. A series of aliphatic thermoplastic poly(amide urethane)s having different short nylon-6 segments (s-PAUs) was prepared. The s-PAUs were characterized by viscometry, gel permeation chromatography, FT-IR, 1H-NMR, solid 13C CP MAS NMR, differential scanning calorimetry, thermogravimetric analysis, wide angle X-ray scattering and tensile tests. Results showed Mn above 29,762, Mw above 36,725, Tm between 128.73 and 171.69 °C, and initial decomposition temperature over 266.25 °C. Tensile strength reached 31.50 MPa with strain at break up to 447.49 %. Some urea linkages were formed during transurethane polycondensation.

Corn oil based poly(ether amide urethane) coating material—Synthesis, characterization and coating properties

Polyetheramide (CPETA) resin was synthesized from N,N-bis (2-hydroxy ethyl) corn oil fatty amide (HECFA) and catechol through condensation polymerization. CPETA was further cured with isophorone diisocyanate (IPDI) in different weight percentage (20, 25, 30, 35, 40wt.%) to obtain poly(ether amide urethane) (CPETAU). The structural elucidation of HECFA, CPETA and CPETAU was carried out by FT-IR, 1H NMR and 13C NMR spectroscopic techniques. Physico-chemical and physico-mechanical properties of these resins were investigated by standard methods. Thermal behavior was assessed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The corrosion resistance performance of CPETAU coatings on mild steel strips was investigated by potentiodynamic polarization studies in different corrosive media (3.5wt.% HCl, 5.0wt.% NaCl, tap water) at room temperature. Amongst all the compositions, CPETAU coatings showed good scratch hardness (2.20kg), impact resistance (150lb/inch), gloss with corrosion rate obtained as 1.377×10−2 (mm/year) and 2.359×10−3 (mm/year) in 3.5wt.% HCl and 5.0wt.% NaCl solution, respectively. CPETAU coatings can be safely used up to 250°C.

Studies on Inter and Intra Molecular Hydrogen Bonding and Morphologies of Single-walled Carbon Nanotubes/polyurethane-amide

Polyurethane (PU) with single-walled carbon nanotubes (SWCNTs) composites were prepared by an in-situ polymerization method, using 1,6-hexane diisocyanate and hydroxyl terminated polybutadiene in tetrahydrofuran. All the composites exhibit as tough films. The PU/SWCNTs blend interactions were studied between the poly(urethane amide), [PUA] functional group and SWCNTs. In the blend matrix, SWCNT interaction with carbonyl amide of PUA is stronger than amide nitrogen of PUA due to the proximity effect of carbonyl groups. This effect leads to block the inter and intra molecular hydrogen bonding within PU matrices. The interaction of SWCNTs with the PUA were examined and studied by ATR-FTIR, Raman spectra, and resistivity study. The “core-shell” tubular bundles morphologies of composites were observed by SEM. All the analyzed data revealed that the SWCNTs were uniformly distributed in PU matrix. These nanotube composite films could be used in the field of aircraft coatings.

Synthesis and characterization of aliphatic segmented poly(ether amide urethane)s through a non-isocyanate route

Two nylon-6 oligomers with polymerization degrees (DP or n) of 6.82 and 4.52 terminated with H2N- and HO-groups (H2N–PAn–OHs) were prepared from caprolactam with ethanolamine via ring-opening polymerization at different molar ratios, and transformed into HO-terminated nylon-6 oligomers (HO–PAn–OHs) through reaction with excess caprolactone. Melt polycondensation of the HO–PAn–OHs, with 1,6-bis(hydroxyethyloxy carbonyl amino)hexane (BHCH) and polyethylene glycols (PEGs), was performed at 170 °C under normal pressure and at 180 °C under reduced pressure of 3 mmHg at different periods. A series of novel aliphatic thermoplastic poly(ether amide urethane)s with different short nylon-6 and PEG segments (s-PEAUs) was prepared. The obtained s-PEAUs were characterized by gel permeation chromatography, FTIR, 1H-NMR, 2D 1H–1H COSY NMR, differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray scattering, and tensile tests. The s-PEAUs exhibited an Mn up to 18 400, an Mw up to 48 900, Tm between 145.94 °C and 177.86 °C, initial decomposition temperature of over 253.39 °C, and tensile strength up to 30.03 MPa with elongation at break of 286.8%. Some urea linkages were formed during transurethane polycondensation.

Anti-microbial and anti-corrosive poly (ester amide urethane) siloxane modified ZnO hybrid coatings from Thevetia peruviana seed oil

The utilization of renewable resources for the development of organic coatings is a viable means of creating alternatives to petroleum-based chemicals which are not eco-friendly. This paper reports the synthesis of polyesteramide–urethane–silica–zinc oxide hybrid coatings from Thevetia peruviana seed oil (TPSO). The periphery of ZnO nano-particles is modified with 3-aminopropyltrimethoxysilane to prepare silica grafted ZnO composite particles. The TPSO based polyesteramide was reacted with 4,4′-diisocyanatodicyclohexylmethane in presence of siloxane modified ZnO to obtain –NCO terminated polyesteramide–urethane–silica ZnO prepolymer. These hybrid pre-polymers were casted on tin foil and cured under atmospheric moisture to obtain eco-friendly, moisture cured polyesteramide–urethanes–silica–zinc oxide hybrid coating films. The synthesized polyester and polyurethane formation was confirmed by using FT-IR and NMR spectroscopic techniques. The resultant hybrid coating films were characterized by using FT-IR, TGA, DSC, SEM, corrosion resistance and microbial resistance. Results confirm that with increase of siloxane modified ZnO content in the polyurethane matrix thermal stability, glass transition temperature and corrosion resistance improved. The antibacterial activity shows that the hybrid films exhibit excellent resistance towards Escherichia coli and Staphylococcus aureus. The salt spray test on coated panel samples show good corrosion resistance properties.

Poly(amide urethane)s with functional/reactive side groups based on a bis-cyclic bio-based monomer/coupling agent

Glycerol and d,l-homocysteine thiolactone – two bio-based building blocks – were used to prepare a bis-cyclic AA′ monomer (or coupler) with an ethylene carbonate and a thiolactone ring linked by an O-methyl urethane spacer. On reaction of this monomer with diamines at 70°C poly(amide urethane)s with pendant thioethyl and hydroxymethyl side groups are produced in one step. Monodisperse diamines of low molecular weight (MW), monodisperse amino telechelic poly(ethylene oxide) (MW=897.10) and polydisperse amino telechelic polytetrahydrofuran (Mn=1100) were used as amine building blocks. By reaction of the coupler with diamines at room temperature only the thiolactone ring is converted. Consequently, a bis(ethylene carbonate) bis(thiol) is obtained if one equivalent diamine is reacted with two equivalents of coupler. Reaction of this intermediate with a second diamine leads to poly(amide urethane)s with pendant thioethyl and hydroxymethyl side groups and alternating amine building blocks. Post-polymerization modification of thiol side groups leads to polymers with designed properties. The microstructure of the obtained polymers was proven by 1H NMR and Raman spectroscopy; the molecular weights were determined by size exclusion chromatography.

Biodegradable Poly(ester–urethane–amide)s Based on Poly(ε-caprolactone) and Diamide–Diol Chain Extenders with Crystalline Hard Segments. Synthesis and Characterization

Twenty seven poly(ester–urethane–amide)s (PEUAs) were synthesized from the reaction of α,ω-telechelic poly(ε-caprolactone) diols, 1,6-hexamethylene diisocyanate, and three different diamide–diol chain extenders derived from ε-caprolactone and three aliphatic diamines with increasing length (n = 2, 4, and 6). The hard segment (HS) was designed to be crystalline and to introduce amide groups, more susceptible to hydrolysis than urethane or urea groups. Crystallization of the HS was achieved even at very low HS content, leading to a phase-separated material. Furthermore, HS crystallinity recovered from the material homogeneous melt on cooling. Thermal degradation was well above HS melting point, allowing for melt processing of these materials. HS melting point was affected by HS content, poly(ε-caprolactone) diol length, and chain extender length. The length scale of the phase-separated morphology lied in between 11 and 13 nm up to ∼60% HS content and decreased at higher HS content values. HS content was the main parameter affecting the mechanical properties. The prepared PEUAs degraded hydrolytically at very long times by surface erosion.

Molecular recognition within a poly(amide urethane) system

The heterodimer recognition within a poly(amide urethane) (PAU) has been achieved through the incorporation of the amphiphilic alkylated nucleobase, 1-hexadecyluracil (U16). The heterodimer recognition led the poly(amide urethane) to exhibit the “plug and play” behavior even the heterodimer recognition coincided with several other hydrogen bonding motifs. In addition, the PAU/U16 blends possess nano-scale lamellar structure of U16 phase within lamellar structure of PAU phase. The nano-scale lamellar structure of the packed U16 gradually transforms from one to the other with the change in the U16 content in the blends.

Microwave assisted synthesis and characterization of olive oil based polyetheramide as anticorrosive polymeric coatings

Virgin olive oil (VOO) based polyetheramide (PEtA) was developed from N-N′-bis(2-hydroxyl ethyl) olive fatty amide (HEOA) and orcinol through condensation polymerization. PEtA was further treated with toluylene 2,4-diisocynate (TDI) with different percentages (20–30wt%) via addition polymerization to obtain poly(ether amide urethane) (PEtAU). The structural elucidation of HEOA, PEtA and PEtAU were carried out by FT-IR, 1H NMR and 13C NMR spectroscopic techniques. Physico-chemical and physico-mechanical properties of the material were investigated by standard methods. Thermal stability and curing behavior of virgin olive oil, HEOA, and PEtAU were assessed by thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The corrosion behavior was investigated by potentiodynamic polarization measurements in different corrosive environments (3.5wt% HCl, 5wt% NaCl, 3.5wt% NaOH, tap water) at room temperature. The results showed that UPEtA coatings exhibit good physico-mechanical as well as corrosion resistance performance and can be safely used up to 200°C. The work is an attempt for alternate utilization of olive oil.