Poly Tetramethylene Glycol Research Articles

Imidazolium‐based ionic thermoplastic polyurethane with low surface energy and antibacterial activities

AbstractA series of novel thermoplastic polyurethane elastomers with both low surface energy and antibacterial activity were synthesized in this paper. Firstly, four imidazole salt diols with different alkyl chain lengths at the N‐position of imidazolium cation ([CnIm+][Cl−]) were prepared. Then, imidazolium‐based ionic thermoplastic polyurethane elastomers (Si‐ITPUs) were formulated by incorporating polydimethylsiloxane and polytetramethylene glycol as a mixed soft segment, 1,4‐butanediol and [CnIm+][Cl−] as a chain extender, and 4,4′‐dicyclohexylmethane diisocyanate. The structure, thermal stability, mechanical properties, physical crosslinking density, and the anti‐graffiti properties of Si‐ITPUs were evaluated. The surface energy and water absorption were evaluated through static contact angle and water resistance tests, respectively. Furthermore, the antibacterial activities against both Staphylococcus.aureus and Escherichia coli were characterized by the plate colony counting method. The results demonstrated that Si‐ITPUs possessed surface energy of approximately 23 mN/m, which conferred excellent anti‐graffiti and self‐cleaning performance. Furthermore, the increase of the alkyl chain length of substitutions resulted in a decrease in the tensile strength but an increase in the elongation at break. Si‐ITPU‐C4 exhibited optimized antibacterial activities with an antibacterial rate of more than 99.9% against both S. aureus and E. coli. This novel polyurethane is anticipated to find applications in the medical device industry and food processing sector.

Gas permeation through polyethylene glycol/polytetramethylene glycol based polyurethane–silica mixed matrix membranes and interfacial morphology study via modeling approach

AbstractA series of mixed matrix membranes (MMMs) based on polyurethane (PU) and silica nanoparticles was fabricated. Three types of PU were synthesized with different polyethylene glycol (PEG)/polytetramethylene glycol ratios (PU0, PU75, and PU100, the corresponding numbers: PEG percent). The MMMs were characterized using FTIR, SEM, and gas permeation measurements (N2, O2, CH4, and CO2). The phase mixing of PU0 and PU75 membranes increased with silica content. This resulted in a decrease in gas permeability, while an increase in CO2/CH4 and CO2/N2 selectivities. The gas separation trend for PU100 membranes was the opposite. The molecular probing approach was served to study the interfacial structure of the MMMs. The existence of a rigidified polymer layer with 2.38 and 2.44 nm thicknesses around silica was revealed through PU0 and PU75 membranes, respectively. In contrary, silica was surrounded by a polymer chain dilution interphase with a thickness of 2.20 nm for PU100 MMMs.

Hydroxyl terminated polybutadiene-based shape memory polyurethane nanocomposites containing nano metal-oxide fillers for microfluidic valve actuator applications

We report here a novel and unique thermo-responsive Shape Memory Polyurethane Nanocomposites (SMPUNCs) derived from Hydroxyl Terminated Polybutadiene (HTPB) and Poly Tetra Methylene Glycol (PTMG) blend encapsulated with nano metal oxides fillers such as CuO, NiO, Fe2O3, CuFe2O4, and Fe2NiO4 for possible use in polymer-based microvalve actuator systems. The synthesis methods adopted and the various characterization techniques employed are presented. The corresponding SMPUs are named PU−CuO, PU−Fe2O3, PU-NiO, PU−CuFe2O4, and PU-Fe2NiO4 respectively. HTPB and PTMG are used as the base polyols for reacting with isocyanates to form the polyurethane base matrix, named as PU-Neat for comparison. Different fillers were used to study the effect of these fillers on the enhancement of the shape memory properties of polyurethane. Morphological, thermal, mechanical, and shape-memory properties of the prepared SMPUs are fully characterized. Morphological studies confirm that all the nano-metal oxide fillers are uniformly dispersed within the SMPU matrix. The shape memory transition temperature (Ttrans), which plays an important role in the shape memory effect (SME), is obtained from DSC analysis. The results show that Ttrans is enhanced with the reinforcement of the nano-metal oxide fillers (resulting in about 10% enhancement in the shape recovery time). The metal oxide filler integrated samples show higher thermal stability as well as shape fixing and recovery performances than PU-Neat. The tensile test confirmed that the PU−Fe2O3 matrix possesses a high tensile modulus and is rigid when compared to other SMPUs. We also demonstrated a microvalve actuator system using PU−Fe2O3, as it possesses the optimum shape recovery and better shape fixing properties, compared to other prepared Shape Memory Polyurethane Nanocomposites. An improvement of 10% efficiency in the closing and opening of the valve for PU composite film was observed in the demonstrated actuator setup.

Carbon nanofiber-reinforced shape memory polyurethanes based on HTPB/PTMG blend as anticorrosive coatings

ABSTRACT Aiming at an easy-processing shape memory polymer, we report different thermo-responsive shape memory polyurethane (SMPU) nanocomposites derived from Hydroxyl Terminated Poly-Butadiene (HTPB) and the Poly Tetra Methylene Glycol (PTMG) encapsulated with different concentrations of carbon nanofiber (CNF) in a cross-linked shape memory polyurethane (PU) matrix. By introducing the optimum concentration of the nanofiller with the PU matrix, we can improve essential properties of PU composites such as morphology, mechanical flexibility, as well as shape memory properties, which are considered the crucial requirement for the effective design of PU composites for a precise application. Two compositions of PU composites were prepared by encapsulating CNF, viz. PU-0.1CNF and PU-0.5CNF, the content of CNF being 1 wt.% and 5 wt.%, respectively. Morphological, thermal, and mechanical studies of these two PU composites show that CNF is homogeneously blended within the PU matrix and well dispersed. The thermal stability of prepared polymer films was evaluated with the help of Thermo-Gravimetry, indicating increased stability with the addition of CNF nanofillers. DSC analysis helps to determine the glass transition temperature (Tg ) as well as the shape transition temperature (Ttrans ). The tensile study confirmed that PU-0.5CNF possesses a greater Young’s modulus value and is not constant in elastic loads. The anti-corrosion property of the prepared SMPU nanocomposite coatings coated over the SS plate was evaluated using a 3.0 wt% NaCl (simulated seawater) solution. Extrapolation of Tafel plots and electrochemical impedance spectroscopy (EIS) provided a higher value of positive corrosion potential (Ecorr ) and a lower value of corrosion current (Icorr ). The electrochemical experiment results demonstrated that PU-0.1CNF nanocomposite coating on SS has better anti-corrosive properties and protection efficiency (PEF% = 98.43%) and behaves like a physical barrier to resist corrosion. These HTPB/PTMG PU nanocomposites exhibit excellent shape memory properties and have a unique composition having both the properties of anti-corrosion and shape memory effects. The results show that by properly selecting the composition we can tailor-make a PU having both anticorrosion and shape memory properties.

Diselenide as a Dual Functional Mechanophore Capable of Stress Self-Reporting and Self-Strengthening in Polyurethane Elastomers

Diselenide as a Dual Functional Mechanophore Capable of Stress Self-Reporting and Self-Strengthening in Polyurethane Elastomers

Effect of crystalline structure on water resistance of waterborne polyurethane

A series of solvent-free waterborne polyurethanes (WPUs) with different soft segment structure were prepared by respectively using different number-average molecular weight (Mn) of polytetramethylene glycol (PTMG, Mn = 1000, 2000, 3000) and poly (1,4-butylene adipate) (PBA, Mn = 1000, 2000 3000) as main diol in this paper. Effect of soft segment crystallization on water resistance of WPUs was discussed. The crystallization properties of WPU films were investigated by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The water resistance was determined by water absorption ratio. DSC and XRD results confirm that there are no crystalline structures in the WPU films which are synthesized with PTMG (Mn = 1000, 2000, 3000) and PBA (Mn = 1000), while the WPU films synthesized with PBA (Mn = 2000 and 3000) have obvious crystalline structures at room temperature. Meanwhile, the WPU films synthesized with PBA (Mn = 2000 and 3000) possess excellent water resistance because the existence of crystalline structure.

Effects of Heterogeneous Linear Polyether Segments on the Membrane Breathability of Nonionic Polyurethane

Characterizing the relationships between the water repellency and moisture permeability (breathability) of hydrophilic polyurethane and its supramolecular structure, including the phase inversion temperature in the soft phase, is unavoidable when developing intelligent, breathable textile products. In this study, a two-step technique was employed to prepare hydrophilic nonionic polyurethanes (PU) with various polyether (PE) soft segments. The hard segments of the samples were composed of 4,4′-diphenylmethane diisocyanate (MDI) and 1,4-butanediol (BDO), while the soft segments consisted of polyethylene glycol 1000 (PEG), polytetramethylene glycol 1000 (PTMG), or their mixture. The relationships between the chemical and physical structure and the breathability were studied. The results showed that the samples with better separated structure between the soft and hard domains had a special microstructure of partial compatibility and simultaneously partial separation between the polyether soft and hard domains. In addition, the distribution of the mixed polyethers in the soft domains was homogeneous. The microphase structure, especially the hydrophilic ether bond content, exhibited a specific corresponding relevancy to the water resistance, moisture permeability and hydrophilicity of the PU membrane. The moisture permeability and water resistance were also directly related to their film-forming properties. Enhanced microphase separation intensified the positive effects of ether bonds on the moisture permeability, while worsened microphase separation weakened their negative influence on the water resistance/hydrophobicity.

Thermal degradation of POSS-containing nanohybrid linear polyurethanes based on 1,6-hexamethylene diisocyanate

Synthesized from 1,6-hexamethylene diisocyanate (HDI), 1,4-butanediol (BDO), poly(tetramethylene)glycol (PTMG), and propanediolisobutyl-POSS (PHI‑POSS) nanohybrid polyurethanes (PU) were examined by TG/FTIR/MS coupled method to determine the mechanism of thermal improvement caused by POSS addition. The measurements were made in both; inert and oxidizing atmosphere for composites containing 0, 6, and 10 % of PHI-POSS. Depending on the concentration of additive, and the surrounding atmosphere we noticed from 5 to 15 °C improvement on different stages of degradation. Among the released gases, mostly tetrahydrofuran (THF), butanediol (BDO), and HDI were recorded, as well as various PTMG-derived ethers and alcohols formed during the depolymerization of segments present in the amorphous phase, as well as amines and amides as decomposition products of segments in the crystalline phase. Interestingly, the release of formates and formaldehyde before the first stage of degradation was observed in the oxidizing atmosphere. The effect of POSS addition causes: (i) reduction of the number of hard domains intensifies the first stage of degradation, but simultaneously increases the onset and the temperature of the maximum rate of decomposition at different stages through preventing some rearrangements leading to breaking of chain, and (ii) formation under elevated temperature conditions of silica-rich char residues that act as a barrier for gas and mass transport.

Gas separation through polyurethane–ZnO mixed matrix membranes and mathematical modeling of the interfacial morphology

AbstractA series of polyurethane/ZnO membranes was fabricated via thermal phase inversion of the solution of polymer/nanoparticle in N,N‐dimethylformamide solvent. The polyurethane synthesis was done via two‐step polymerization method using polytetramethylene glycol, isophorone diisocyanate, and 1,4‐butanediol in the ratio of 1:3:2. Different concentrations of zinc oxide nanoparticles (5, 10, 15, and 20) were incorporated into the polyurethane matrix. FTIR, SEM, and X‐Ray analysis were performed to characterize the membranes. FTIR and SEM results suggests an increment in the phase mixing of polyurethane with ZnO loading. Gas permeation performance through polyurethane‐ZnO mixed matrix membranes with ZnO loading by as much as 20 wt% were elucidated for pure N2, O2, CH4, and CO2 and gases. Based on the results, all permeability values decreased as the loading of ZnO nanoparticles increased, whereas CO2/N2 and CO2/CH4 selectivities increased. Moreover, interfacial structure of the polyurethane/ZnO nanocomposites were characterized by molecular probing approach. The results revealed the presence of a rigidified polymer chain layer with 65 ± 6 Å thickness around the ZnO nanoparticles.

Effect of structure of nonisocyanate condensation polyurethanes based on benzoic acid on its susceptibility to biodegradation

The present study investigates the effect of the biodegradation time on the properties of condensation segmented nonisocyanate polyurethanes (NIPUs) using the aerobic strain of Gordonia alkanivorans. Polyurethane samples were prepared from phenolsulfonic acid, benzoic acid, polytetramethylene glycol (PTMG 1000) or oligooxypropylene triol (G 1000) and different amounts of formaldehyde. The emulsifying activity, protein concentration, pH, tensile strength and strain at break were evaluated as function of biodegradation time and formaldehyde content. The existence of a segmented structure was confirmed by the existence of two phase transitions in the glass transition temperatures of flexible segments and melting temperatures of hard segments. The tensile strength (TS) of NIPUs based on PTMG 1000 and 50% excess of formaldehyde decreased by about 20%, 60% and 95% after 10, 21 and 90 days of biodegradation. TS decrease was less pronounced for NIPUs prepared from G1000. The 21 days biodegradation caused the most significant changes in the pH, emulsifying activity and protein concentration. The highest degree of cross-linking induced by an excess of formaldehyde led to the highest resistance of NIPU to Gordonia alkanivorans. The DSC, FTIR, SEM and element concentration analyses demonstrated that biodegradation occurred mainly in hydrolysis sensitive hard segments and, to a lesser extent, in flexible oligomerol segments.

Polyurethane/Nanosilver-Doped Halloysite Nanocomposites: Thermal, Mechanical Properties, and Antibacterial Properties.

In this study, the researchers successfully embellished the surface of halloysite (Ag/HNTs) with silver using halloysite, silver nitrate (AgNO3), and polyvinylpyrrolidone (PVP). The researchers then prepared polyurethane that contained pyridine ring by using 4,4′-diphenylmethane diisocyanate (MDI) and polytetramethylene glycol (PTMG) as the hard chain segment and the soft chain segment of polyurethane (PU), as well as 2,6-pyridinedimethanol (2,6-PDM) as the chain extension agent. This was followed by the preparation of Ag/HNTs/PUs nanocomposite thin films, achieved by mixing Ag/HNTs with different ratios into polyurethane that contains pyridine ring. First, the Ag/HNTs powders were analyzed using energy-dispersive X-ray spectroscopy, X-ray diffraction, and transmission electron microscopy. Subsequently, Fourier-transform infrared spectroscopy was used to examine the dispersibility of Ag/HNTs in PU, whereas the thermal stability and the viscoelasticity of Ag/HNTs/PU were examined using thermal gravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis. When the mechanical properties of Ag/HNTs/PU were tested using a universal strength tester, the results indicated a maximum increase of 109.5% in tensile strength. The researchers then examined the surface roughness and the hydrophobic ability of the Ag/HNTs/PU thin films by using atomic force microscopy and water contact angle. Lastly, antibacterial testing on Escherichia coli revealed that when the additive of Ag/HNTs reached 2.0 wt%, 99.3% of the E. coli were eliminated. These results indicated that the addition of Ag/HNTs into PU could enhance the thermal stability, mechanical properties, and antibacterial properties of PU, implying the potential of Ag/HNTs-02 as biomedicine material.

Curing processes of binary epoxy-amine systems for manufacturing epoxy-silica films

ABSTRACT Binary epoxy resins, diglycidyl ethers of bisphenol A and polytetramethylene glycol, were cured by binary amine hardeners, isophorone diamine and polyoxybutylene diamine, in the presence/absence of NH2-functionalized SiO2 nanoparticles. Four different molar ratios of the monomers were stoichiometrically used in the curing processes. The fabricated films of the epoxy thermosets were quite transparent and flexible, and fully analyzed using FE-SEM, FT-IR, XRD, and DR-UV/vis spectroscopy. The molar absorption coefficients (ɛ) of the epoxy-silica composites decreased with increasing the molar ratio of diglycidyl ether of polytetramethylene glycol and polyoxybutylene diamine in the mixtures. According to the DMA studies, no phase separation was observed in the composition of the networks obtained. When the prepared epoxy thermosets were charged by silica nanoparticles, the peaks related to the α relaxation of the polymer chains appeared at higher temperatures. Moreover, TGA measurements showed that the thermal stabilities of the resulting epoxy networks slightly increased by adding SiO2 nanoparticles. Also, the thermal stability somewhat decreased with increasing the molar ratio of the polyoxybutylene-containing monomers.

Structure and performance of waterborne polyurethane-acrylate composite emulsions for industrial coatings: effect of preparation methods

Waterborne polyurethane-acrylate (WPUA) composite emulsions were prepared by the physical blending method, graft emulsion polymerization method, and interpenetrating network (IPN)-based method using polytetramethylene glycol (PTMG), isophoronediisocyanate (IPDI), and acrylic monomers (methyl methacrylate (MMA) and butylacrylate (BA)) as the main raw materials. The WPUA polymers were characterized based on their water resistance, morphologies, thermal, spectroscopic and mechanical properties. Graft WPUA film had the highest tensile strength and the best thermal stability, indicating that the strength of the chemical bond between PU and PA plays an important role in modulating the performances of the WPUA films. The results showed that the graft WPUA has excellent integrated properties and thus a potential application in the coating industry.

Elucidating the effect of chain extenders substituted by aliphatic side chains on morphology and gas separation of polyurethanes

Novel poly(urethane-urea) (PUU) membranes were developed as the aim of a structure-property relationship study to enhance gas permeation. Designing the PUUs was followed by three synthesized chain extenders with different length-alkyl side chains, polytetramethylene glycol, and isophorone and hexamethylene diisocyanates. The longest substituted PUU indicated higher phase separation and lower glass transition temperature. Pure and mixed gas permeabilities of prepared membranes grew as phase separation of PUU material increased, while fractional free volume decreased by lengthening the side chain of the PUUs. The reasons for this event were the migration of the side chains to the surface of hard domain, thereby shielding it and filling the soft/hard interface. Enhanced permeability of materials with longer side chains is attributed to its plasticizing effect. The highest CO2 permeability (287 barrer) was obtained for the longest substituted PUU. The findings revealed an increase in gas permeation without a significant reduction of selectivity by longer substituted PUUs.

Unsaturated canola oil-based polyol as effective nucleating agent for polyurethane hard segments

The polyurethane (PU) phase separation could significantly affect its properties. Many factors influence PU phase separation, including soft and hard segments type, their content, and presence of external components such as nanoparticles. The aim of this research was to control the PU phase separation behavior by an internal component which was chemically bonded in PU backbone. For this purpose, a low molecular weight polyester was synthesized and used as a co-soft segment for PU synthesis. The polyester was synthesized by hydroxylation and esterification reaction of unsaturated bonds of raw Canola oil. The PUs were synthesized by two-step polymerization method of poly tetramethyleneglycol (PTMG) and synthesized polyester as soft segments, hexamethylene diisocyanate (HDI), and 1,4 butanediol in 1:3:2 M ratio. In order to study the chemical structure of synthesized materials, specifying the nucleating ability of the synthesized polyol for hard segments, as well as studying its effects on PU properties, different analysis including Fourier Transform Infrared Spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction analysis (XRD), Dynamic Mechanical Thermal Analysis (DMTA) and gas permeability were used. Results showed that the presence of the synthesized polyester in the PU structure significantly affects its properties and caused appearance of a new domain for hard segments. These results suggested that polyester polyol can change the PU micro-phase separation by changing hard segments crystalline order.

Silver(I) complex with a Schiff base ligand extended waterborne polyurethane: A developed strategy to obtain a highly stable antibacterial dispersion impregnated with in situ formed silver nanoparticles

In this study, as a novel strategy to overcome gel formation and coagulation problem of waterborne polyurethane (WPU) dispersions containing silver ions, a Schiff base ligand (SBL) derived from 2,4-dihydroxybenzaldehyde and Bis(3-aminopropyl)amine was synthesized and utilized as chain extender in fabrication of WPUs. The effect of SBL incorporation into WPU chains and subsequent complex formation with Ag ions on the storage stability and particle size of the dispersions were studied. The UV–vis spectroscopy results of prepared dispersions confirmed the formation of Ag NPs within the WPUL/Ag sample through in situ reduction of Ag ions by PTMG (polytetramethylene glycol) polyol as a non-toxic reducing agent. Transmission electron microscopy (TEM) images of WPUL/Ag dispersion demonstrated that the formed Ag NPs exhibited a spherical shape with a size below 10 nm. Furthermore, X-ray diffraction (XRD) analysis of WPUL/Ag film affirmed the presence of Ag NPs within the WPUL matrix. Scanning electron microscopy (SEM) photographs of WPUL/Ag film also displayed a homogeneous dispersion for in situ formed Ag NPs. Antibacterial assays showed an excellent activity for WPUL/Ag film against S. aureus and P. aeruginosa bacteria. Besides, in vitro cytotoxicity studies confirmed that the WPUL/Ag sample possess a good biocompatibility toward L929 cells.

Bisphenol A Diglycidyl Ether-Based Epoxy Networks with Enhanced Storage Moduli Using Silica Nanoparticles Coated by NH2-Functionalized Poly(tetramethylene oxide)

Isocyanate-capped chains of poly(teramethylene oxide) (PTMO) are synthesized by the reaction of hexamethylene diisocyanate and polytetramethylene glycol in 2 : 1 molar ratio. Then, the resulting telechelic macrochains are covalently grafted to silica nanoparticles via formation of urethane linkages. Amine-functionalized silica nanoparticles coated by soft and flexible shell of poly(teramethylene oxide) are obtained after hydrolysis of the remaining isocyanate end groups. These organo-silica nanoparticles are homogeneously loaded into diglycidyl ether of bisphenol A epoxy resin in two different contents, i.e. 5 and 10 wt %. Alongside isophorone diamine as the main hardener of the resin, amine groups of the poly(teramethylene oxide)-grafted nanoparticles allow them to participate effectively in the hardening process. The resulting epoxy/silica nanocomposites are thoroughly characterized by field emission-scanning electron microscopy, fourier transform infrared spectroscopy, and X-ray diffraction. Dynamic mechanical thermal analysis showed that the filler considerably enhances storage moduli of the resulting nanocomposites. However, probing the thermal properties of the epoxy/silica nanocomposites by thermogravimetric analysis and differential thermal analysis showed that the filler has no significant effect on the heat stabilities and thermal phase transitions.

CO2 separation over light gases for nano-composite membrane comprising modified polyurethane with SiO2 nanoparticles

Owing to the potential of polymeric and nanocomposite membranes for industrial application in CO2 capturing and gas separation processes, permeation properties of CO2, N2 and O2 through the polymer matrix have been an object of extensive research. We measured the permeation rates of gases (pure and mixed gas) within a novel nanocomposite membrane composed of poly tetramethyleneglycol (PTMG), hexamethylene diisocyanate (HDI), and diamine chain extender, 4,4-methylenebis(2-chloroaniline) (MOCA) at various silica loadings and operating conditions. The novel polyurethane was prepared by a two-step bulk polymerization technique based on the molar ratios of the used constituents 1 : 3 : 2 for PTMG: HDI: MOCA, respectively The FTIR spectra indicated that the extent of phase separation decreased by increase in the SiO2 content From the DSC and XRD analyses, the existence of small crystalline areas within the soft and hard segments of matrix was proved High thermal stability of new nanocomposites was authenticated by a 90 °C increase in the decomposition temperature upon including the SiO2 particles into the polymer matrix By providing a longer diffusion path, a reduction in the permeation of penetrants occurred after the incorporation of SiO2 content By raising the temperature from 25 to 45 °C, the gas permeation value of CO2, O2 and N2 rose steeply: 35, 54 and 81% in neat PU and 49, 64 and 137% in PU containing 15 wt%, respectively Conversely, the obtained results for increasing the feed gas pressure from 6 to 10 bar revealed that the penetration of non-condensable gases, O2 and N2, decreased while the permeation rate of CO2 polar gas surged dramatically Nevertheless, a simultaneous increment in the selectivity amounts of both gas pairs was revealed. For the gaseous mixtures, the trend of changes in permeability and selectivity values were almost identical with those of pure gas: decrease in permeation, and vice versa increase in gas pair selectivity Eventually the separation results of the prepared membranes indicated a strong tendency to move towards Robeson's line by incorporation of SiO2 nanoparticles into the matrix of membranes.

Preparation and properties of fluorosilicone polyether polyurethane underwater acoustically transparent encapsulant

Fluorosilicone polyether polyurethane (FSPU) was successfully prepared from polytetramethylene glycol, hydroxyl fluorosilicone oil, toluene diisocyanate and chain extender 2,4-diamino-3,5-dimethylthiotoluene. The obtained material was characterized by Fourier transform infrared spectroscopy, dynamic mechanical analysis and scanning electron microscopy. And the water resistance, mechanical and acoustic performance of the materials were tested by video optical contact angle measuring instrument, electronic universal testing machine and sound field, respectively. The results showed that the glass transition temperature of FSPU was lowered and the cold resistance was improved with the addition of hydroxyl fluorosilicone oil. When the amount of hydroxyl fluorosilicone oil was 40 wt%, the water contact angle of FSPU increased to 113.6°, and the water absorption reached a minimum of 0.7%. Compared with polyurethane, the hydrophobic performance of FSPU was significantly improved. The insertion loss of FSPU-40 at 1000 kHz was only 220.60 dB/m, which was 68.7% lower than that of polyurethane. Above all, FSPU has excellent water resistance, cold resistance and acoustic performance, and is an ideal material for underwater acoustically transparent encapsulant.

Outstanding cavitation erosion resistance of hydrophobic polydimethylsiloxane‐based polyurethane coatings

ABSTRACTCavitation erosion will create shock waves and water jets in turbulent flows. These impact pressures will affect the surface, which will lead to crack propagation and severe material degradation. In this study, we have developed hydrophobic polydimethylsiloxane‐based polyurethanes (Si‐PUx) with hydroxypropyl polydimethylsiloxane (H‐PDMS) and polytetramethylene glycol (PTMG) as mixed soft segments and 2,4‐tolylene diisocyanate, 1,4‐butanediol, triethanolamine as hard segments via a polycondensation reaction and studied its properties. The cavitation wear experiment showed that the cavitation erosion resistance of Si‐PUx coating continuously improved with the increase of H‐PDMS content, while the adhesion force of Si‐PUs reduced with the increasing of H‐PDMS content. The surface of Si‐PUx coating after cavitation test was observed using an optical microscope and three‐dimensional profiler. The cumulative mass loss of Si‐PUx with 12.5 wt % H‐PDMS was only 2.96 mg and the surface showed no obvious holes and cracks after 80 h cavitation. The results showed that cavitation resistance had a correlation with degree of water resistance, hardness, adhesion strength, and dynamic mechanical properties of coating. It seemed that the Si‐PUx coating could withstand a longer period cavitation erosion resistance compared to high strength epoxy, which could be used as protective coating for flow components under water. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2019,136, 47668.