Dicyclohexylmethane Diisocyanate Research Articles

Synthesis of MDI-50 and Tung Oil-Based Non-Ionic Waterborne Polyurethanes

A series of MDI-50 based non-ionic waterborne polyurethane dispersions (MDI-NPUD) were prepared by the mixing of 2,4’-diphenylmethane diisocianate (2,4’-MDI) and 4,4’-MDI (MDI-50) which reacted with hydroxylated tung oil (HTO) and polyethylene glycol-800 (PEG-800), Fourier Transform Infrared Spectroscopy (FTIR) and Proton-Nuclear Magnetic Resonance (1H-NMR) were used to characterize and analyze their molecular structures. The results indicated that MDI-50 and HTO were introduced as hard segment while PEG acted as soft segment. The surface tension, Hydrophile-Lipophile Balance (HLB) and stability were investigated. All MDI-NPUDs had much lower surface tension than the dicyclohexyl methane diisocyanate (HMDI) based NPUD (HMDI-NPUD). By changing the feed ratio of MDI-NPUD, the properties of MDI-NPUD could be controlled

Effect of polymer microstructure on the docetaxel release and stability of polyurethane formulation

PurSil®AL20 (PUS), a copolymer of 4,4′-dicyclohexylmethane diisocyanate (HMDI), 1,4-butane diol (BD), poly-tetramethylene oxide (PTMO) and poly-dimethyl siloxane (PDMS) was investigated for stability as a vehicle for Docetaxel (DTX) delivery through oesophageal drug eluting stent (DES). On exposure to stability test conditions, it was found that DTX release rate declined at 4 and 40°C. In order to divulge reasons underlying this, changes in DTX solid state as well as PUS microstructure were followed. It was found that re-crystallization of DTX in PDMS rich regions was reducing the drug release at both 4°C and 40°C samples. So far microstructural features have not been correlated with stability and drug release, and in this study we found that at 40°C increase in microstructural domain sizes and the inter-domain distances (from ∼85Å to 129Å) were responsible for hindering the DTX release in addition to DTX re-crystallization.

Synthesis and characterization of biodegradable polyurethanes with unsaturated carbon bonds based on poly(propylene fumarate)

ABSTRACTThe segmented polyurethanes synthesized from biodegradable polyesters are very promising and widely applicable because of their excellent physiochemical properties. Poly(propylene fumarate) (PPF), a kind of linear aliphatic unsaturated and biodegradable polyesters, has been well recognized in biomedical applications. Herein novel polyurethanes (PPFUs) were synthesized based on the PPF‐diol, diisocyanates such as 1,6‐diisocyanatohexane, l‐lysine diisocyanate, and dicyclohexylmethane diisocyanate, and chain extenders such as 1,4‐butylene glycol and l‐lysine methyl ester hydrochloride (Lys‐OMe·2HCl). By varying the types of diisocyanates, and chain extenders, and the proportion of hard segments, the PPFUs with tailored properties such as mechanical strength and degradation rate were easily obtained. The synthesized PPFUs had an amorphous structure and slight phase separation with strong hydrogen bonding between the soft segments and the hard segments. The elongation of PPFU elastomers reached over 400% with a slow deformation‐recovery ability. The PPFUs were more sensitive to alkaline (5 M, NaOH) hydrolysis than acid (2 M, HCl) and oxidative (30 vol.%, H2O2) erosion. The tensile strength, deformation‐recovery ability, and glass transition temperature of the PPFUs were improved with the increase of hard segment proportion, while the degradation rate was opposite because of the faster degradation of the soft segments. In vitro culture of smooth muscle cells in the extractant of the PPFUs or on the PPFUs film surface revealed low cytotoxicity and good cytocompatibility in terms of cell viability, adhesion, and proliferation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42065.

Synthesis and Properties of Novel Non-Ionic Polyurethane Dispersion Based on Hydroxylated Tung Oil and Alicyclic Isocyanates

Hydroxylated Tung oil (HTO) based nonionic polyurethane dispersion (HTO-NPUD) were synthesized using dicyclohexyl methane diisocyanate (HMDI) and HTO as main hydrophobic materials whereas polyethylene glycol-800 (PEG-800) as hydrophilic chain extender. To effectively study the effects of HTO on properties of NPUD, polypropylene glycol-400(PPG-400) based NPUD was prepared by HMDI reacting with PPG-400 and PEG-800. The structures of those novel nonionic polyurethane dispersions were characterized by FTIR and 1H NMR. Moreover, particle size and size distribution, cloud point and surface tension had been investigated. Results showed that, by comparing with PPG based NPUD (PPG-NPUD), the introduction of HTO into NPUD result in larger particle size and more uniformed particle size distribution, higher cloud point and lower surface tension.

Effects of wide‐range γ‐irradiation doses on the structures and properties of 4,4′‐dicyclohexyl methane diisocyanate based poly(carbonate urethane)s

For medical applications, 4,4′‐dicyclohexyl methane diisocyanate (HMDI)‐based poly(carbonate urethane)s were synthesized from HMDI and 1,4‐butanediol as hard segments and poly(carbonate diol) (number‐average molecular weight = 2000 g/mol) as soft segments. The effects of wide‐range γ irradiation on the samples were examined through a series of analytical techniques. Scanning electron microscopy revealed that γ irradiation etched and roughened the surfaces of the irradiated samples. The gel content and crosslinking density measurements confirmed that crosslinking occurred along with degradation at all of the investigated irradiation doses and the degree of both crosslinking and degradation increased with increasing irradiation dose. Fourier transform infrared spectroscopy demonstrated that chain scission in the γ‐irradiated samples occurred at the carbonate and urethane bonds. The decreasing molecular weight and tensile strength indicated that the degradation increased with the γ‐irradiation dose. Differential scanning calorimetry and dynamic mechanical thermal analysis indicated that γ irradiation had no significant effect on the phase‐separation structures. There was a slight reduction in the contact angle. An evaluation of the cytotoxicity demonstrated the nontoxicity of the nonirradiated and irradiated polyurethanes. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41049.

Synthesis, characterization and biodegradation studies of poly(ester-urethane)s

A series of aliphatic poly(ester-urethane)s (PEUs) with different NCO/OH ratio were synthesized by a two-step bulk polymerization process from aliphatic poly(neopentyl-succinate) (PNSu), 4,4’-dicyclohexylmethane diisocyanate and 1,3-propanediol as a chain extender in the presence of dibutyltindilaurate as a catalyst. PNSu was prepared by the transesterification polycondensation from diethyl succinate and neopentyl glycol in the presence of titanium isopropoxide as a catalyst. The effect of the NCO/OH ratio on the structural, physical and thermal properties of PEUs was studied by Fourier transform infrared spectroscopy, X-ray diffraction, proton nuclear magnetic resonance, gel permeation chromatography, density measurement, differential scanning calorimetry, thermogravimetric analysis/differential thermogravimetric analysis and optical microscopy. The density (ρ) and number-average molecular weight (Mn) of PEUs are found to be in the range of 1·175–1·180 g/cm3 and 55 137–56 947 g/mol, respectively. The biodegradability of the PEUs film was investigated by hydrolytic (in 3% sodium hydroxide solution) and enzymatic degradation (Aspergilus niger lipase in phosphate buffer solution pH = 7·2) at 37°C. PEUs film shows a slower degradation rate in A. niger lipase compared with the hydrolytic process.

New insight into microstructure-mediated segmental dynamics in select model poly(urethane urea) elastomers

Segmental dynamics in a series of 4,4′-dicyclohexylmethane diisocyanate–diethyltoluenediamine–poly(tetramethylene oxide) based poly(urethane urea) (PUU) elastomers have been investigated through a multi-scale characterization approach. This includes broadband dielectric analysis, solid-state nuclear magnetic resonance (NMR), plate impact, and impulsive stimulated scattering. Dielectric relaxation measurements applicable at frequencies up to 106 Hz are useful for interpreting the high strain-rate deformation response; i.e. at the moment of target interaction with an accelerating impact or MHz stress wave excitation. Additionally, the capability of solid-state NMR to differentiate the microstructure-mediated segmental dynamics; correspondingly, the presence of a rigid phase (those in the phase-mixed regions) and a mobile phase associated with the soft-segment domains is demonstrated. These new insights not only further elucidate the microstructure details discerned through atomic force microscopy, but also enable the prediction of the macroscopically dynamic response in these model PUUs, particularly on the temporal scale over the range of μs–ns.

Synthesis and properties of waterborne polyurethane adhesives: effect of chain extender of ethylene diamine, butanediol, and fluoro-butanediol

Waterborne polyurethane (WBPU) adhesives were prepared using poly(tetramethylene oxide glycol), 4,4’-dicyclohexylmethane diisocyanate (H12MDI), hydrophilic agent dimethylol propionic acid and chain extender of 2,2,3,3-tetrafluoro-1,4-butanediol (TFBD), ethylene diamine (EDA), and 1,4-butanediol. All three chain extenders have been used as single and mixed (different ratio) content during synthesis, and the effect of chain extender and their content to the properties of tensile strength, Young’s modulus, water swelling (%), and adhesive strength was investigated. The adhesive strength value was higher using EDA as a single-chain extender; however, the potentiality of adhesive strength under water was improved using mixed-chain extenders of EDA and TFBD in WBPU adhesives. The maxima potentiality was observed with 6.31 mole% TFBD and 2.10 mole% EDA in WBPU adhesives.

Atmospheric Pressure Photoionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Characterization of Tunable Carbohydrate-Based Materials for Sorption of Oil Sands Naphthenic Acids

Synthetically engineered copolymers are receiving growing attention for sorption and possible degradation of components in oil sands processed water (OSPW). β-Cyclodextrin (β-CD) copolymers, for example, have been shown in recent studies of electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to adsorb oil sands naphthenic acid fraction components (NAFCs). Herein, we report complementary results for atmospheric pressure photoionization (APPI) for characterization of NAFCs in OSPW samples following sorption with cyclodextrin-based copolymers. The materials investigated were β-CD-cross-linked with three different types of diisocyanates, namely, (i) 4,4′-dicyclohexylmethane diisocyanate, (ii) 4,4′-diphenylmethane diisocyanate, and (iii) 1,4-phenylene diisocyanate. The APPI studies revealed variable sorption for a complementary range of NAFCs with compound classes not detected by ESI. For example, sorption was observed for new classes of NAFCs: HC, N1O1, N1O2, ...

Properties of waterborne polyurethane‐fluorinated marine coatings: The effect of different types of diisocyanates and tetrafluorobutanediol chain extender content

ABSTRACTThree series of waterborne polyurethane‐ (WBPU) fluorinated coatings were prepared with single aliphatic (4,4′‐dicyclohexylmethane diisocyanate, H12MDI), aromatic (4,4′‐diphenylmethane, MDI) and a mixture of aliphatic and aromatic diisocyanates (1 : 1). Different contents of 2,2,3,3‐tetrafluoro1,4‐butanediol (TFBD) as a chain extender were used in the WBPU coatings. The fluoro‐enriched surface of the WBPU coatings was obtained with a combination of a high TFBD content (8.77 mol %) as well as the aliphatic or mixed diisocyanates. The tensile strength, Young's modulus, elongation at break (%) and adhesive strength were characterized with respect to the TFBD contents. The mechanical strength and adhesive strength increased with increasing TFBD content in the three series. In artificial salt water, the maximum adhesive strength of WBPU was observed for this coating, which was achieved by TFBD bonded H12MDI of mixed diisocyanates with a higher TFBD content (8.77 mol %). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39905.

Tunable Polymeric Sorbent Materials for Fractionation of Model Naphthenates

The sorption properties are reported for several examples of single-component carboxylic acids representing naphthenic acids (NAs) with β-cyclodextrin (β-CD) based polyurethane sorbents. Seven single-component examples of NAs were chosen with variable z values, carbon number, and chemical structure as follows: 2-hexyldecanoic acid (z = 0 and C = 16; S1), n-caprylic acid (z = 0 and C = 8; S2), trans-4-pentylcyclohexanecarboxylic acid (z = -2 and C = 12; S3), 4-methylcyclohexanecarboxylic acid (z = -2 and C = 8; S4), dicyclohexylacetic acid (z = -4; C = 14; S5), 4-pentylbicyclo[2.2.2]octane-1-carboxylic acid (z = -4; C = 14; S6), and lithocholic acid (z = -6; C = 24; S7). The copolymer sorbents were synthesized at three relative β-CD:diisocyanate mole ratios (i.e., 1:1, 1:2, and 1:3) using 4,4'-dicyclohexylmethane diisocyanate (CDI) and 4,4'-diphenylmethane diisocyanate (MDI). The sorption properties of the copolymer sorbents were characterized using equilibrium sorption isotherms in aqueous solution at pH 9.00 with electrospray ionization mass spectrometry. The equilibrium fraction of the unbound carboxylate anions was monitored in the aqueous phase. The sorption properties of the copolymer sorbents (i.e., Qm) were obtained from the Sips isotherm model. The Qm values generally decrease as the number of accessible β-CD inclusion sites in the copolymer framework decreases. The chemical structure of the adsorbates played an important role in their relative uptake, as evidenced by the adsorbate lipophilic surface area (LSA) and the involvement of hydrophobic effects. The copolymers exhibit molecular selective sorption of the single-component carboxylates in mixtures which suggests their application as sorbents for fractionation of mixtures of NAs. By comparison, granular activated carbon (GAC) and chitosan sorbents did not exhibit any significant molecular selective sorption relative to the copolymer materials; however, evidence of variable sorption capacity was observed among the sorbents investigated.

Effect of H12MDI isomer composition on mechanical and physico-chemical properties of polyurethanes based on amorphous and semicrystalline soft segments

Two series of segmented thermoplastic polyurethanes were synthesized having 33 wt % hard segment based on 4,4′-dicyclohexyl methane diisocyanate with different trans–trans isomer contents and 1,3-propanediol chain extender. The soft segments were based on poly(hexamethylene–pentamethylene carbonate)diol and poly(butylene sebacate)diol, amorphous and semicrystalline polyol, respectively. 4,4′-Dicyclohexyl methane diisocyanate with different trans–trans isomer contents were obtained by fractional crystallization of commercial diisocyanate and were characterized by differential scanning calorimetry and nuclear magnetic resonance spectroscopy. 4,4′-Dicyclohexyl methane diisocyanate trans–trans isomer lead to some interesting properties in the synthesized polyurethanes, due to the more ordered hard domains formed by packing of trans–trans 4,4′-dicyclohexyl methane diisocyanate. Thereby, as 4,4′-dicyclohexyl methane diisocyanate trans–trans isomer content increased, a better phase separated structure was observed.

Composition, thermal and tensile properties of polyurethane-urea-silica hybrids

Polyurethane-Urea-Silica (PUUS) hybrid solutions were synthesized by a two-stage process, based on the use of polyoxypropylene glycol (PPG), 4,4′-dicyclohexyl methane diisocyanate (H12MDI), 1,4-butane diol, 3-aminopropyl-trimethoxysilane (APrTMOS) and a suitable amount of solvent. Following knife-coating and curing reaction, polyurethane/urea/silica hybrid films were prepared with different crosslinkages and silica contents through the in situ sol–gel process. The intermolecular bonding of hydrogen bonding between N–H, CO groups of PU and area and Si–O–Si crosslinked structure of APrTMOS was determined via FTIR analysis, and was correlated with thermal/tensile properties. FTIR and ESCA results indicate that the carbonyl, N–H and Si–O groups distribution contained in PU and hybrid films characterized as CO group absorption peak area ratio, N/C and Si/C atomic ratio were changed from the film's surface to the bulk with APrTMOS content. Intermolecular bonding, composition, thermal property and tensile strength of films were functions of the APrTMOS contents and PPG's molecular weight. All hybrid films exhibit a more significant change in glass transition temperature (Tg), decomposition temperatures (Td), coefficients of thermal expansion (CTEs) and stress-strain properties than that with pure PUs. The correlation between intermolecular bonding, composition, thermal and tensile properties were investigated.

Influence of microstructure on micro-/nano-mechanical measurements of select model transparent poly(urethane urea) elastomers

Morphology of 4,4′-dicyclohexylmethane diisocyanate–poly(tetramethylene oxide) (PTMO)–diethyltoluenediamine based poly(urethane urea) (PUU) elastomers is investigated by atomic force microscopy (AFM) and compared with elastic modulus data measured from AFM-enabled indentation, dynamic nanoindentation (nanoDMA), and dynamic mechanical analysis (DMA). These measurements highlight the effect of altering the molecular weight (Mw) of PTMO, which is used as a soft segment (SS), on the microstructure. In particular, at SS Mw 2000 g/mol, a strong microphase-separated morphology is observed, whereas a phase-mixed dominated microstructure is noted in PUU with SS Mw of 1000 and 650 g/mol. These observations are also consistent with DMA tan δ results. Furthermore, instrumented impact indentation is also utilized for elucidation of dynamic damping characteristics in these PUUs.

Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Characterization of Tunable Carbohydrate-Based Materials for Sorption of Oil Sands Naphthenic Acids

The potential for sorption and possible degradation of components in oil sands processed water (OSPW) by the use of synthetically engineered co-polymers is receiving growing attention. Recent research has highlighted the sorption of total oil sands naphthenic acid fraction components (NAFCs) by β-cyclodextrin (β-CD) co-polymers. The incorporation of β-CD within co-polymer frameworks represents a novel modular approach with significant potential for controlled tuning of the textural mesoporosity of the sorbents. Herein, we report the Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) characterization of aqueous samples containing oil sands NAFCs following sorption with a range of cyclodextrin-based co-polymers. The materials investigated were β-CD cross-linked with three different types of diisocyanates, namely, (i) 4,4′-dicyclohexylmethane diisocyanate, (ii) 4,4′-diphenylmethane diisocyanate, and (iii) 1,4-phenylene diisocyanate. Variable sorption of NAFCs was observed according to the cross-linking density of the co-polymer framework and the nature of the cross-linker unit. Furthermore, the sorption of the NAFCs by the co-polymers was not affected by other parameters, such as metal ions, salinity, and non-oil sands acid fractions present in OSPW. The observation of molecular selective sorption in co-polymer materials containing β-CD represents an important contribution toward the development of sorbent materials for the controlled removal of oil sands acids in aquatic environments. The FT-ICR MS measurements also contribute further to the understanding of the thermodynamic sorption mechanism of such materials.

Enzymatic activity studies of Pseudomonas cepacia lipase adsorbed onto copolymer supports containing β-cyclodextrin

Pseudomonas cepacia lipase (PCL) was immobilized onto polyurethane copolymers containing β-cyclodextrin (β-CD) via physisorption. The polymer bound PCL was characterized using an equilibrium sorption method, Fourier transform infrared (FTIR) spectroscopy with attenuated total reflectance (ATR), Raman spectroscopy, and powder X-ray diffraction (PXRD). The objective of this research was to investigate lipase immobilization onto polyurethane copolymers and an investigation of its enzymatic activity. The copolymers contain β-CD with two types of crosslinker units: 4,4′-dicyclohexylmethane diisocyanate (CDI) and 4,4′-diphenylmethane diisocyanate (MDI), respectively. Immobilization of PCL resulted in a pronounced increase in catalytic activity and stability of lipase (∼three-fold for CDI and ∼four-fold for MDI) in comparison with free lipase in aqueous solution. PCL exhibited remarkable hydrolytic activity over a range of pH (5–9) values, temperatures (25–65 °C), and solvents (mostly non-polar). The immobilized lipase was further used for the synthesis of n-butyl octanoate ester using n-butanol and octanoic acid. The immobilized lipase was successfully recycled four times while maintaining ∼75–80% esterification activity after the fourth catalytic cycle and exhibited appreciable stability for at least 30 days.

Waterborne polyurethanes: influence of chain extender in ftir spectra profiles

Abstract Non-polluting systems based on waterborne polyurethanes (wPU) and poly(urethane-urea)s (wPUU) were synthesized employing poly(propylene glycol) (PPG), dimethylolpropionic acid (DMPA) and 4,4′-dicyclohexylmethane diisocyanate (HMDI) as monomers. In the formulations, the length and the proportion of the soft segments were varied. Three types of chain extenders were employed: ethylene glycol (EG), producing urethane linkages; and ethylenediamine (EDA) and hydrazine (HYD), forming urea linkages. Cast films obtained from wPU and wPUU, monomers and prepolymers were analyzed by Fourier transform infrared spectrometry (FTIR). The profile of carbonyl absorption bands obtained for the films showed some remarkable differences depending on the formulation. The bands were split into two parts, which were directly related to the tendency of hydrogen bond formation. The length of soft segment, the amount of rigid portions and the presence of urea linkages showed a marked influence in both intensity and frequency absorption of the bands.

Influence of diisocyanate structure on the morphology and properties of waterborne polyurethane-acrylates

Polyurethane (PU)-acrylic hybrid composites were prepared by emulsion polymerization of acrylic monomers in the presence of preformed PU chains containing polymerizable terminal vinyl groups. To study the effect of the nature of diisocyanate on the film's morphology and properties, composites were prepared from two different diisocyanates: tetramethylxylene diisocyanate and 4,4′-dicyclohexylmethane diisocyanate. The samples were then characterized using size exclusion chromatography, dynamic light scattering, transmission electron microscopy, Fourier-transformed infrared spectroscopy (FTIR) and small-angle X-ray scattering (SAXS), and the gel fraction content and mechanical properties of the films were also determined. The hybrid composites were found to be cross-linked systems that underwent changes in their particle and film morphologies with increasing acrylic content. The FTIR results revealed a good interaction between the PU and acrylic moieties, and SAXS experiments showed that systems with up to a 50 wt% acrylic component were homogeneous. An attempt to incorporate a higher amount of acrylic component resulted in phase-separated materials. The composition at which phase separation was observed was found to be strongly dependent on the diisocyanate structure. Although the properties of hybrid samples with lower acrylic contents were dependent on the diisocyanate used, samples with higher acrylic contents behaved similarly to those of pure acrylic regardless of the diisocyanate used for preparation. The diisocyanate structure has an important role in the phase separation behavior of hybrid materials. SAXS curves for both PUs show the typical broad band at q=0.1 Å−1. Incorporation of the acrylic component reduced the intensity of this maximum. Hybrid based on H12MDI has a high degree of phase mixing for 50 wt% acrylic content but a separated phase at 70 wt% is observed. TMXDI-based hybrids that form homogeneous systems with higher acrylic content and phase separation are observed only at 90 wt%.

Synthesis and Characterization of Polyurethanic Proton Exchange Membranes

Novel proton exchange membranes have been prepared by in synthesis functionalization of a polyurethane matrix with a sulfonic group containing chain terminals. The synthesis procedure was based on the use of two polyethylene glycols with nominal molecular weight of 300 and 1 k and 4,4′ dicyclohexylmethane diisocyanate in presence of the sodium salt of isethionic acid as a donor of the sulfonic group. Glycerol was added in order to improve by reticulation the stability of the cast films. The membranes were characterized in terms of swelling, morphology, methanol permeability, proton conductivity, and ion exchange capacity. The best H2/air cell performance was achieved at 80 °C with a maximum power density of 16.9 mW/cm2 at a voltage of about 0.35 V. Polyurethane based ionomeric membranes have proved to be interesting candidates for proton exchange membrane fuel cells (PEMFC) applications.

Properties of Waterborne Polyurethane Adhesives with Aliphatic and Aromatic Diisocyanates

A series of waterborne polyurethane (WBPU) adhesives were prepared with various ratios of aliphatic/aromatic diisocyanates, namely 4,4′-dicyclohexylmethane diisocyanate (H12MDI) as an aliphatic diisocyanate and 4,4′-diphenylmethane diisocyanate (MDI) as an aromatic diisocyanate with poly(tetramethyleneoxideglycol) (PTMG), ethylene diamine (EDA) and dimethylol propionic acid (DMPA). 1H-NMR spectroscopy was utilized to investigate the side reaction at the dispersion step during synthesis of WBPU dispersions with respect to aliphatic, aromatic and mixed diisocyanates. The tensile strength, Young's modulus, elongation at break (%), storage modulus, glass transition temperature and adhesive strength were measured with respect to aliphatic/aromatic diisocyanate contents. The adhesive strength was maximum using mixed diisocyanates containing 25 mol% MDI in WBPU adhesives.