Methylenedi-p-phenyl Diisocyanate Research Articles

Structure and properties of polylactide toughened by polyurethane prepolymer

ABSTRACTIn this study, polyurethane prepolymer (PUP) was prepared by the reaction of Poly‐1,4‐butylene glycol adipate diol (PBA) and 4,4′‐Methylenedi‐p‐phenyl diisocyanate (MDI). The as‐prepared PUP was then blended with Polylactide (PLA), and the impact of the PUP on the blends regarding their structure and properties were thoroughly analyzed. Also, PLA was blended with PU powder without isocyanate groups (NCO) as an important control sample (PLAPW) to study the interface interaction of the blends. Obvious yield and neck stretch were obtained after the addition of PUP, and the elongation ratio at break increased from 2.9% to 231.5%. In contrast, the mechanical properties of PLAPW decreased significantly mainly due to the simple physical blending of the polymers without the formation of covalent bonds. Also, the results of the FTIR, SEM, DSC, and DMA analysis showed that the reactions of NCO groups in PUP with the terminal hydroxyl or carboxyl groups in PLA significantly improved the compatibility of the PUP and PLA blend. Compared to pristine PLA, the highest decomposition temperature of the PLA and PUP blend (PLAPU) increased from 359.3°C to 362.6°C. Additionally the thermal stability and mechanical properties of the blended materials were exceedingly improved even with only 5% of PUP in the blended materials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42983.

A one-pot preparation of silk fibroin modified with polyurethane micro-particles

In this study, polycaprolactone (PCL) tetrol and 4,4′-methylenedi-p-phenyl diisocyanate (MDI) were initially mixed for 10 min at 40 °C, then immediately added to a silk fibroin (SF)–water mixture. The obtained mixture was then added into a mixer to prepare the modified SF. The effects of the polyurethane prepolymer (PUP) content in the modified SF on the structure and properties of the modified SF were investigated. Fourier transform infrared spectroscopy (FTIR) revealed that urethane linkages formed between the SF and the PUP, and that the grafting ratio of the PUP used for preparing the modified SF was 99.1%. Polyurethane micro-particles were dispersed throughout the SF matrix of the modified SF and interacted with the SF matrix through urethane linkages, which strengthened the interface between the two phases. This special structure led to improved strength and elongation of the modified SF at break. The urethane-linked SF and PUP improved the mechanical properties and gave a higher thermal stability than other materials prepared by physical mixing. In addition, compared with the pure silk fibroin, the modified SF demonstrated a higher strength and elongation at break, along with better flexibility and hydrophobicity. These properties were also improved as the PU content was increased. Therefore, a simple and effective method to prepare high performance modified SF was successfully developed.

Starches modified with polyurethane microparticles: Effects of hydroxyl numbers of polyols in polyurethane

In this work, three different types of polycaprolactone (PCL) polyols-PCL diol, PCL triol and PCL tertol were used to synthesize polyurethane prepolymers (PUPs) with 4, 4′-methylenedi-p-phenyl diisocyanate (MDI). The obtained PUPs then were used to modify thermoplastic starch (TPS) in an intensive mixer. Results showed that the grafting ratio of PUP used for modified starch was 99.6±0.2%, and the hydrophobicity of the modified starches improved compared to that of pure starch. With the increasing OH numbers of polyols in PUP, the compatibility between polyurethane and starch was improved. The toughness and thermal stability of modified starches were thus increased while the crystallinity of starch decreased. In addition, due to the existence of dense cross-linking, there was strong interaction between starch and PCL tertol based PUP, and the modified starch showed excellent toughness compared to pure starch. The superiorly formed, modified starch could have great potential applications.

Synthesis, characterization, and thermal degradation of new aromatic poly(azomethine-urethane)s and their polyphenol derivatives

A new polyurethane was synthesized by condensation reaction of 2,4-dihydroxy benzaldehyde (DHB) with methylene-di-p-phenyl-diisocyanate (MDI) under argon atmosphere. The synthesized polyurethane was converted to its poly(azomethine urethane) species (MP-2AP, MP-3AP, and MP-4AP) by graft copolymerization reactions with amino phenols (2-amino phenol, 3-amino phenol, and 4-amino phenol). Obtained poly(azomethine urethane)s (PAMUs) were converted to their polyphenol species (P-MP-2AP, P-MP-3AP, and P-MP-4AP) by oxidative polymerization reaction (OP) using NaOCl as the oxidant. The structures of the obtained compounds were confirmed by FT-IR, UV–vis, 1H-NMR, and 13C-NMR techniques. The molecular weight distribution parameters of the synthesized compounds were determined by the size exclusion chromatography (SEC). The synthesized compounds were also characterized by solubility tests, TG-DTA, and DSC analyses. Thermal decomposition steps at various temperatures were clarified by FT-IR analyses of degraded products. Fluorescence measurements were carried out in various concentrated DMF solutions to determine the optimum concentrations to obtain the maximal PL intensities.

Hydrophobic Thermoplastic Starches Modified with Polyester-Based Polyurethane Microparticles: Effects of Various Diisocyanates

It is critical to prepare ductile and hydrophobic modified starch material in an effective and environmentally friendly way. In this work, polyurethane prepolymers (PUPs) with various isocyanates were synthesized and mixed reactively with thermoplastic starches (TPS) in an intensive mixer to prepare modified TPS. The effects of the isocyanates on the structure and properties of the modified TPS were then investigated by using scanning electron microscope (ESEM), tensile tester, and contact angle meter. Results showed that mechanical properties of the modified TPS were improved with the increase in hydrophobicity of the isocyanate. 4,4′-Methylenedi-p-phenyl diisocyanate (MDI) was hydrophobic, the NCO groups in PUPs were not easily consumed by water when modified starch was prepared, leading to a significantly increased reaction of the NCO groups with starch. As the amount of urethane bonds between starch and PUP increased, the compatibility between the two polymers was also improved, resulting in the impro...

Synthesis and characterization of biodegradable elastomeric polyurethane scaffolds fabricated by the inkjet technique

Biodegradable polyurethanes (PUs) were synthesized from methylene di- p-phenyl-diisocyanate (MDI), polycaprolactone diol (PCL-diol) and N, N-bis (2-hydorxyethyl)-2-aminoethane-sulfonic acid (BES), serving as a hard segment, soft segment and chain extender, respectively. MDI was chosen due to its reactivity and wide application in synthesis of biomedical polyurethanes due to its reactivity; PCL-diol was chosen because of its biodegradability; and BES was chosen because it allowed the introduction sulfonic acid groups onto the polymer chains. We evaluated the polyurethanes' degradation rate, mechanical properties, hydrophilicity, antithrombogenecity, and ability to support fibroblast cell attachment and growth by comparing with polymers having a 2,2-(methylimino)diethanol (MIDE) chain extender. Mechanical testing demonstrated that the PU containing BES has tensile strengths of about 17 MPa and elongations up to 400%, about three times the strength and four times the elongation than the MIDE based PUs. The polymers showed decreased in vitro degradation rates, lower glass transition temperature ( T g) and hydrophilicity possibly due to enhanced microphase separation. Preliminary cytocompatibility studies showed that all the PUs are non-toxic, but PU containing BES exhibited much lower cell attachment and proliferation than the MIDE chain extended polymers. An in vitro platelet adhesion assay showed lower platelet attachment on BES containing PU. Additionally, due to the existence of sulfonic acid groups, the BES extended PU became water soluble in basic condition and insoluble in acidic condition, a phenomenon that is reversible at pH value of 8.7, making this a pH sensitive polymer attractive for bioprinting applications. By adding acetic acid into an inkjet cartridge and printing it onto a PU solution with pH above 8.7, precision fabricated scaffolds can be obtained, suggesting that BES based PUs are promising candidates as synthetic inks used for customizable fabrication of tissue engineering scaffolds.

Improving the elasticity and cytophilicity of biodegradable polyurethane by changing chain extender

Two types of biodegradable polyurethanes (PUs) were synthesized from methylene di-p-phenyl-diisocyanate (MDI), polycaprolactone diol (PCL-diol), and chain extenders of either butanediol (BD) or 2,2'-(methylimino)diethanol (MIDE). The effects of two types of chain extenders on the degradation, mechanical properties, hydrophilicity, and cytophilicity of PUs were evaluated. In vitro degradation studies showed that PU containing MIDE has a higher degradation rate than PU synthesized using BD as a chain extender. Mechanical testing on dry and wet samples demonstrated that PU containing MIDE has a much higher elongation in the elastic region than PU containing BD. PU containing MIDE is more hydrophilic and retains more liquid during in vitro culture. Furthermore, preliminary cytocompatibility studies showed that both types of degradable PU are nontoxic, and fibroblasts adhere better and proliferate faster on MIDE containing PU than BD containing PU. To compare the cytocompatibility and degradation behaviors of the synthesized PU with existing FDA approved biocompatible material, polylactide (PLA), with a similar degradation rate, was used as negative control. Two types of PU were shown to have similar cytocompatibility and degradation behaviors as those of the PLA material. To verify the effectiveness of the cytotoxicity assay, latex was used as a positive control. Latex samples showed toxicity to cultured cells as expected. In conclusion, by changing the type of chain extender used during the synthesis of degradable PUs, the degradation rate, mechanical properties, hydrophilicity, and cytophilicity can be adjusted for different tissue engineering applications.

One-pack cross-linkable waterborne methyl ethyl ketoxime-blocked polyurethane/clay nanocomposite dispersions

One-pack cross-linkable nanocomposites of waterborne methyl ethyl ketoxime (MEKO)-blocked aromatic polyurethane dispersion (BPUD) reinforced with organoclay (quaternary ammonium salt of Cloisite 25A) were synthesized by the acetone process using 4,4′-methylenedi-p-phenyl diisocyanate (MDI), poly(tetramethylene) glycol (PTMG), dimethylol propionic acid (DMPA), and methyl ethyl ketoxime (MEKO). Particle size, viscosity, and storage stability of these nanocomposites were investigated. TEM and XRD studies confirmed that the silicate layers of organophilic clay were exfoliated and intercalated at a nanometer-scale in the BPUD matrix.

Synthesis and characterization of polyurethane–urea nanoparticles containing methylenedi‐p‐phenyl diisocyanate and isophorone diisocyanate

AbstractWater‐based polyurethane–urea (WPUU) nanoparticles containing 4,4′‐methylenedi‐p‐phenyl diisocyanate (MDI) and isophorone diisocyanate (IPDI) were synthesized by a stepwise prepolymer mixing process, that is, the consecutive formation of hydroxyl‐terminated and isocyanate‐terminated polyurethane prepolymers. The reaction behavior, chemical structure, and consequent morphology of the polyurethane prepolymers and WPUU were investigated with Fourier transform infrared (FTIR), gel permeation chromatography, and NMR techniques with MDI concentrations ranging from 0 (pure IPDI) to 50% with respect to the total moles of isocyanate. Wide‐angle X‐ray diffraction and differential scanning calorimetry patterns showed that the crystallinity of WPUU, which mostly originated from crystallizable poly(tetramethylene adipate) polyol, was significantly affected by the MDI content. Both the crystallinity and melting temperature of WPUU decreased as the MDI content increased. Deconvoluted relative peak areas of the carbonyl region in the FTIR spectrum revealed that the effect of hydrogen bonding among the hard segments became favorable as the MDI content increased, whereas the hydrogen bonding of the soft segments significantly decreased. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4353–4369, 2004

Differentiation of the mechanism of micronuclei induced by cysteine and glutathione conjugates of methylenedi- p-phenyl diisocyanate from that of 4,4′-methylenedianiline

Methylenedi- p-phenyl diisocyanate (MDI) is widely used in the production of polyurethane products. Diisocyanates are reactive compounds, MDI can react under physiological conditions with various functional groups found on biological molecules resulting in conjugate formation or undergo non-enzymatic hydrolysis to form 4,4′-methylenedianiline (MDA). We have previously reported that addition of MDI directly to Chinese hamster lung fibroblasts (V79) cultures did not induce micronuclei (MN), but MDA, and the glutathione and cysteine conjugates of MDI (BisGS–MDI and BisCYS–MDI), induced a concentration-dependent increase in the frequency of MN. The conventional MN assay does not discriminate between MN produced by acentric chromosome fragments from those arising due to whole lagging chromosomes that were not incorporated into daughter nuclei at the time of cell division. The mechanism of MN induction from these potential MDI metabolites/reaction products was explored in the present study using immunofluorescent staining of kinetochore in MN of cytokinesis-blocked V79 cells. This assay discerns the presence of centromere within the MN to distinguish the MN containing centric chromosomes from those containing acentric fragments. Eighty five percent of MDA-induced MN were negative with respect to anti-kinetochore antibody binding (KC −). This is consistent with an interaction between MDA and DNA resulting in chromosome breakage. However, BisGS–MDI and BisCYS–MDI induced a higher percentage of MN that were positively stained by the anti-kinetochore antibody (KC +). These results suggest that the mechanism of MN formation induced by BisGS–MDI and BisCYS–MDI is mediated through disruption and/or by affecting the function of the mitotic spindle. This mechanism is distinctly different from the mechanism of MN induction by MDA.

Coating water‐swellable polymer latexes by interfacial polymerization

AbstractTwo techniques of coating water‐swellable polymer latexes (hydrogels) with an inorganic or organic layer were developed, based on interfacial polymerization. The hydrogel latexes were prepared by inverse suspension polymerization. The first kind of interfacial polymerization is hydrolysis and polycondensation of tetraethyl orthosilicate (TEOS) or 3‐(trimethoxysilyl) propylmethacrylate (TMS‐PMA) on the surface of hydrogel latexes. The hydrochloric acid, which is the catalyst for this reaction, was previously loaded into the hydrogel latexes. The HCL‐containing hydrogel latexes were then suspended in an organic solution of TEOS or TMS‐PMA. The hydrolysis and condensation occur only at the surface of each hydrogel particle and the generated SiO2 or SiO(PMA) network covers the hydrogel latexes. The second interfacial polymerization is polymerization of methylenedi‐p‐phenyl diisocyanate (MDI) and triethylene glycol (TEG) on the surface of hydrogel latexes. TEG was deposited on the hydrogel by suspending the hydrogel powder in a tetrahydrofuran (THF) solution of TEG and evaporating the THF. The TEG‐deposited hydrogel powder was then suspended in an organic solution containing both MDI and the catalyst dibutyltin dilaurate (DBTL). The MDI and DBTL molecules react with the TEG molecules only at the surface of the hydrogel particles, and the polyurethane P(MDI‐TEG) thus formed wraps the particles. Based on these two coating procedures, three kinds of materials were obtained: SiO2 coated hydrogels, SiO‐(PMA) coated hydrogels and P(MDI‐TEG) coated hydrogels. Soft polyether brushes were grafted to the SiO‐(PAM) coated latexes. The P(MDI‐TEG) coated hydrogels were used as reservoirs for β‐hydroethyltheophylline (β‐HETP), and the release of the latter molecules from the coated hydrogels was investigated. © 1995 John Wiley & Sons, Inc.