Methylene Dicyclohexyl Diisocyanate Research Articles

Mapping oft the optimal mechanical responses in commercial‐grade HTPB‐based binders

AbstractAlternative binders for composite solid propellants (CSP) have always been a concern. One of the closest alternative to the broadly used military‐grade hydroxyl‐terminated polybutadiene (HTPB) would be its commercial‐grade. Factorial design of experiments (DoE) was applied to optimize the mechanical properties of the binder. Commercial‐grade HTPB was used, in addition to 1,4‐butanediol (BDO) as chain extender, and either isophorone diisocyanate (IPDI) or 4,4’‐methylenedicyclohexyl diisocyanate (H12MDI) as curing agents. The effect of simultaneously varying two factors: [NCO]/[OH] molar ratio, and BDO:HTPB mass fraction on the mechanical properties of the binder was evaluated. DoE gave the optimal conditions at 0.68 molar ratio, and 0.71 % BDO:HTPB mass fraction for IPDI; and at 0.66 and 0.57 %, respectively, for H12MDI. Higher strength was observed for binders formulated with H12MDI. At the optimal conditions, CSP formulated with commercial HTPB showed higher strength than CSP formulated with military HTPB. Moreover, with H12MDI higher elongation was observed (28±4 %) when compared to IPDI (19±1%). Thus, the former is a promising diisocyanate for tailoring CSP formulations with commercial‐grade HTPB.

Nanoparticle-free, recyclable, and photothermal-responsive castor-oil-based shape memory polyurethane with regulatable mechanical properties and antibacterial activity

Photothermal shape memory polyurethanes (SMPUs) have attracted more and more attention due to their precision, flexibility, and remote control. However, the current photothermal SMPUs often rely on petroleum-based resources and utilize inorganic or metal nanoparticles as photothermal agents, which would not only cause a resource crisis but also pollute the environment. In addition, their own non-recyclability would further expand the drawbacks mentioned above. Herein, we report nanoparticle-free, recyclable, and photothermal-responsive castor oil (CO)-based shape memory polyurethanes (denoted BPUs), which are synthesized by CO, 1,4-benzoquinone dioxime (BQDO), and 4,4′- methylenedicyclohexyl diisocyanate (HMDI). Benefits from the rational molecular design, the mechanical properties of BPUs can undergo a wide range of changes from soft to tough and then to hard. Compared with the control sample, the σ and E of BPUs are increased by 9.6–29.8 times and 3–854 times, respectively. They also showed exceptional malleability, reprocessability, recyclability, and dual-shape memory due to dynamic oxime-carbamate bonds formed by BQDO reacting with isocyanate. Specifically, after several thermal remodeling BPUs, their mechanical properties can basically return to more than 92% of the original sample. Moreover, BPUs can maintain Rf and Rr above 90% after several shape memory-reconstruction cycles. More importantly, BPUs have excellent photothermal performance due to the color and conjugate structure of BQDO. For example, BPU-2 can reach 102.1 °C after being exposed to NIR light with a power density of 0.8 W/cm2 for about 50 s. At the same time, several functional applications of BPUs have been developed based on the excellent photothermal performance of BQDO, such as photothermal shape memory, photothermal engines, and photothermal antibacterial (sterilization rate is around 99%). This work provides new enlightenment for the high-value utilization of CO-based SMPUs; and certain reference significance for the sustainable development of photothermal SMPUs.

Synthesis and Characteristics of Eco-Friendly 3D Printing Material Based on Waterborne Polyurethane.

Photo-cured 3D architectures are successfully printed using the designed waterborne polyurethane-acrylate (WPUA) formulation. A WPUA series is synthesized in the presence of polycaprolactone diol (PCL) and 4,4′-methylene dicyclohexyl diisocyanate (H12MDI) as the soft segment part, dimethylolbutanoic acid (DMBA) as the emulsifier, and triethylamine (TEA) as the neutralizer, as a function of prepolymer molecular weight. The compatibility of WPUA and the photo-activating acryl monomer is as a key factor to guarantee the high resolution of 3D digital light processing (DLP) printing. The optimized blending formulations are tuned by using triacrylate monomers instead of diacrylate derivatives. For the high-accuracy and fine features of 3D DLP printing, WPUA are designed to be a suitable molecular structure for a 385 nm wavelength source, and the target viscosity is achieved in the range from 150 to 250 Cp. Photo-cured 3D architectures based on WPUA exhibit good flexural strength and high resolution.

Evaluation of cytotoxicity, hemocompatibility and spectral studies of chitosan assisted polyurethanes prepared with various diisocyanates.

In this research work cytocompatibility, mutagenicity, and hemolytic activity of chitosan-based polyurethanes (PUs) have been evaluated. The chitosan modified PUs were prepared by step-growth polymerization technique using various diisocyanates like isophorone diisocyanate (IPDI). 4,4'-methylenedicyclohexyl diisocyanate (H12MDI), 2,4-toluene diisocyanate (TDI) and hexamethylene diisocyanate (HMDI) by reacting with hydroxyl-terminated polybutadiene (HTPB). Structural confirmation of prepared samples was done by FTIR-ATR and 1H NMR techniques. Chitosan bearing PU samples showed good hemocompatibility, non-mutagenic behavior and less or non-cytotoxic behavior with all the diisocyanates. Among all the diisocyanates, aromatic diisocyanate (TDI) showed less hemocompatibility, high mutagenicity, and more cytotoxicity. However, this still showed a better result than non-chitosan based sample. It is concluded that chitosan improved the biological behavior of PU samples.

Zwitterionic–polyurethane coatings for non-specific marine bacterial inhibition: A nontoxic approach for marine application

The present work reports synthesis and development of zwitterionic tri-block copolymer-polyurethane (ZTC-PU) coatings which are thermally stable and have hydrophobic properties which can be used for marine applications. The zwitterionic tri-block copolymer (ZTC) (poly(sulfobetaine methacrylate) - polydimethylsiloxane - poly(sulfobetaine methacrylate), polySBMA-block-PDMS-block-polySBMA) was synthesized by ATRP (atom transfer radical polymerization) method. Apart from this, the facile synthesis of silane functionalized acrylic polyol was formulated with 4,4′- Methylene dicyclohexyl diisocyanate (H12 MDI) for the development of polyurethane (PU) coatings. Different weight ratios of ZTC was incorporated in PU to obtain a zwitterionic tri-block copolymer-polyurethane (ZTC-PU) coatings. The ZTC-PU coating exhibit good thermal stability and hydrophobic property. The coating showed excellent non-specific marine bacterial inhibition property along with good stability against gram positive Staphylococcus aureus (S. aureus) and gram negative Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) microbial strains. This design method reveals the development of zwitterionic-polyurethane coatings with higher amount of zwitterionic moiety in the coating system, that will be efficient and eco-friendly technology for marine bio-fouling application.

Flexible aliphatic poly(isocyanurate–oxazolidone) resins based on poly(ethylene glycol) diglycidyl ether and 4,4′‐methylene dicyclohexyl diisocyanate

ABSTRACTNew flexible aliphatic oxazolidone‐isocyanurate networks (AISOX) are obtained by reacting a low molecular weight diisocyanate (4,4′‐methylene dicyclohexyl diisocyanate, H12MDI) and a macro‐diepoxyde (poly(ethylene glycol) diglycidyl ether, Mn = 526, PEGDGE) in different molar ratio. The curing reaction, carried out from 25 °C to 200 °C, is studied by using DSC and FTIR. The effect of the molar ratio of the two monomers on thermal and mechanical properties of AISOX resins is investigated by DSC, thermogravimetric analysis, stress−strain measurements and optical microscopy. Independently from the feed composition, it is observed that the reaction steps are: (i) partial hydrolysis of isocyanate caused by water traces, (ii) incomplete trimerization of isocyanate to give isocyanurate, and (iii) formation of oxazolidone and complete conversion of isocyanate. At the highest concentration of the soft macrodiepoxyde (PEGDGE), the AISOX resin is in the rubbery state at room temperature and shows an elastomeric behavior. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43404.

Degradability in vitro of polyurethanes based on synthetic atactic poly[(R,S)-3-hydroxybutyrate

The aim of the present study was to determine the degradability of aliphatic polyurethanes, based on a different amount of synthetic, atactic poly[(R,S)-3-hydroxybutyrate] (a-PHB), in hydrolytic (phosphate buffer) and oxidative (H2O2/CoCl2) solutions. The soft segments were built with atactic poly[(R,S)-3-hydroxybutyrate] and polycaprolactone or polyoxytetramethylenediols, whereas hard segments were the reaction product of 4,4'-methylenedicyclohexyl diisocyanate and 1,4-butanediol.The selected properties - density and morphology of polymer surfaces - which could influence the sensitivity of polymers to degradation processes - were analyzed.The analysis of molecular mass (GPC), thermal properties (DSC) and the sample weight changes were undertaken to estimate the degree of degradability of polymer samples after incubation in environments studied.Investigated polyurethanes were amorphous with the very low amount of crystalline phases of hard segments.The polyurethane synthesized with a poly[(R,S)-3-hydroxybutyrate] and polyoxytetramethylenediol at a molar ratio of NCO:OH=3.7:1 (prepolymer step) appeared as the most sensitive for both degradative solutions. Its weight and molecular mass losses were the highest in comparison to other investigated polyurethanes.It could be expected that playing with the amount of poly[(R,S)-3-hydroxybutyrate] in polyurethane synthesis the rate of polyurethane degradation after immersion in living body would be modeled.

Nitrogen rich hyperbranched polyol via A3 + B3 polycondensation: thermal, mechanical, anti-corrosive and antimicrobial properties of poly (urethane-urea)

High performance, high solid and low in volatile organic content (VOC) multifunctional coatings have wide applications in protection and decoration of materials. This work describes the synthesis of novel hyperbranched polymer (HBP) based polyurethanes (PUs) that exhibit antimicrobial property and are environmentally benign. Nitrogen rich HBP having nitrogen atom as a core was synthesized by A3 + B3 polycondensation in two step reaction. In the first step, monomer A3, a tricarboxylic acid, was synthesized by triethanolamine (B3, the core) with succinic anhydride, while in the second step, monomers A3 and B3 were used to synthesize hyperbranched polyester polyol by polycondensation reaction. The HBP thus formed was reacted with 4,4′-methylenedicyclohexyl diisocyanate (H12 MDI) in varying ratios of NCO to OH to form NCO- terminated PU prepolymers in a self-catalyzed reaction. The prepolymers were then coated onto mild steel panels as well as tin foils and stored at ambient conditions for 20 days to evaluate the moisture-cured PU-urea film properties. The formation of tribasic acid (A3), HBP and PU was confirmed by 1H NMR, 13C NMR, FTIR and ESI-mass spectroscopy. Thermal, mechanical, anti-corrosive and antimicrobial studies as well as the effect of varying NCO to OH ratio on these properties were investigated. The properties of PU-urea were found to be suitable for corrosion protection as well as biomedical and various other applications.

Polyurethanes Based on Atactic Poly[(R,S)-3-hydroxybutyrate]: Preliminary Degradation Studies in Simulated Body Fluids

The aliphatic polyurethanes based on atactic poly[(R,S)-3-hydroxybutyrate] (a-PHB) and commercial oligomerols: poly(e-caprolactone)diol and polyoxytetramethylenediol were investigated. a-PHB was obtained by anionic ring-opening polymerization of (R,S)-β-butyrolactone. The 4,4′-methylenedicyclohexyl diisocyanate and 1,4-butanediol were used as contributors of hard segments. The aim of the study was to determine the influence of synthetic, atactic a-PHB in soft segments of polyurethanes on their degradability in simulated body fluids (SBF) and Ringer solution. The incubation of polymer samples in both degradative solutions was carried out for 36 weeks. It was concluded that the presence of a-PHB in polyurethane structure accelerated their degradation in SBF and in Ringer solution and, protected the calcification process.

Infrared light actuated shape memory effects in crystalline polyurethane/graphene chemical hybrids

A series of crystalline shape memory polyurethanes (SMPUs) were synthesized from polycaprolactone diols and 4,4′-methylenedicyclohexyl diisocyanate (H12MDI) with chemical incorporation of allyl isocyanate modified graphene oxide (iGO) into the PU. Actuation of hybrid SMPUs by infrared (IR) absorption of iGO as well as the direct heat actuated SMPUs has been studied in terms of the isothermal crystallization rate, near-IR absorption, and thermal, mechanical, and shape memory properties. It was found that iGO functions as a multifunctional cross-linker at low contents and a nucleating agent at high contents, and as a reinforcing filler, while light absorption by the iGO induced melting of the PU soft segment, giving rise to a shape recovery of over 90% at 1% iGO (G10).

The structure of novel polyurethanes containing synthetic poly[(R,S)‐3‐hydroxybutyrate

AbstractThe aim of this study was to estimate the structure of new polyurethanes with the potential to be used in medicine. Atactic poly[(R,S)‐3‐hydroxybutyrate], obtained via a ring‐opening polymerization, and polycaprolactonediol or polyoxytetramethylenediol were used to built the soft segments. 4,4′‐methylene dicyclohexyl diisocyanate and 1,4‐butanediol were the components to form hard segments. At FTIR spectra of obtained polyurethanes the bands attributed to NCO groups completely disappeared, similarly as these of OH groups and the new band characteristic for stretching vibrations of bonded urethane NH groups appeared. Polyurethanes with low‐molecular weight were obtained. The observation of FTIR and 1H‐NMR spectra had been suggested that NH groups form two types of hydrogen bonds: with CO urethane (possibly with ester group) and ether groups. An addition of poly[(R,S)‐3‐hydroxybutyrate] caused the slight increase in number of urethane–urethane hydrogen bonds. For some of polyurethanes (based on polyoxytetramethylenediol) the allophanate structures were obtained. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Chain-extending of Hydroxytelechelic Polybutadiene: Synthesis and Characterization

Extension of hydroxytelechelic polybutadiene oligomers ( 3200 g/mol) is performed in mild conditions, in order to avoid backbone modifications, using succinic anhydride or methylenedicyclohexyl diisocyanate. The two routes present significative extension of the initial oligomers. Extension through the anhydride route, in the presence of DCC and DMAP, leads to new hydroxytelechelic oligomers ( 8000 g/mol). Extension through the diisocyanate route, catalyzed by DBTL at 65°C leads to hydroxytelechelic oligomers of higher average molecular weight ( 20000 g/mol). New materials are characterized by FTIR/1H-NMR and changes in their Tg according to , are discussed. The influence of reaction time on the length of the macromolecular chains is also studied.

FTIR spectroscopic characterization of polyurethane-urea model hard segments (PUUMHS) based on three diamine chain extenders

Six polyurethane-urea model hard segments (PUUMHS) were prepared by a solution method based, respectively, on two isocyanates: 4,4′-methylene-diphenyl-diisocyanate (MDI), 4,4′-methylene-dicyclohexyl diisocyanate (HMDI) and three amine chain extenders: ethylene diamine (EDA), methylene-bis-ortho-chloroaniline (MOCA), 2,4-diamino-3,5-dimethylsuphylchlorobenzene (DDSCB). FTIR was used to study their spectroscopic characterization. The main FTIR bands of the six samples were assigned and compared. It was found that most of N–H and C O are H-bonded in these PUUMHS. However, the N–H in three MDI based PUUMHS is all in the stronger H-bond state than that in their corresponding HMDI based while the C O in three HMDI based PUUMHS is all in the stronger H-bond state than that in their corresponding MDI based, respectively. In addition, the order of the H-bond strength in HMDI based PUUMHS is MOCA, DDSCB and EDA whether according to νN H or νC O band wavenumbers, which is, however, different from that in MDI based PUUMHS. Moreover, the HMDI based PUUMHS shows obvious double amide III bands while the MDI based has only prominent one. The results are discussed according mainly to the different characteristics of the three chain extenders as well as the structure difference between MDI and HMDI.

Synthesis, characterization and platelet adhesion studies of novel ion-containing aliphatic polyurethanes

Two novel ion-containing aliphatic polyurethanes based on 4,4′-methylene dicyclohexyl diisocyanate (H 12MDI), polytetramethyl oxide (PTMO) were synthesized using either sulfonated or carboxylated chain extender. The nonionic polyurethane chain extended with 1,4-butanediol, which is denoted as H–M–BD, was synthesized. Pellethane ®, a biomedical-grade polyurethane, was also studied for comparison. The polymer's bulk, surface, and platelet-contacting properties were studied using Fourier transform infrared spectrophotometry, differential scanning calorimetry, water absorption analysis, electron spectroscopy for chemical analysis, static contact angle analysis, and in vitro platelet adhesion experiments. The effects of ion incorporation on the morphology, surface properties and blood compatibility are discussed. Unlike MDI-based Pellethane ®, all H 12MDI-based polyurethanes are not composed of crystalline hard segment domain but are amorphous. The ionic polyurethanes exhibit a smaller fraction of hydrogen-bonded carbonyl groups, poorer phase separation, smaller fraction of PTMO residing at the surface, and smaller contact angle; however, significant higher water absorption value than H–M–BD and Pellethane ®. The in vitro platelet adhesion experiments indicated that ion incorporation, especially for carboxylate, significantly reduced the number and the degree of activation of the adherent platelets.

Synthesis, characterization, and platelet adhesion studies of novel aliphatic polyurethaneurea anionomers based on polydimethylsiloxane-polytetramethylene oxide soft segments

Two novel aliphatic polyurethaneurea anionomers were synthesized based on polydimethylsiloxane (PDMS)-polytetramethylene oxide (PTMO) soft segments. The hard segments consisted of either 4,4'-methylene dicyclohexyl diisocyanate (H12MDI), sulfonic acid-containing diol and 1,4-butandiol (BD) or H12MDI, carboxylic acid-containing diol and BD. The nonionic counterpart chain extended with BD was prepared. In addition, the base nonionic polyurethaneurea containing a pure PDMS soft segment, which is denote H-D-BD, was also studied for comparison. The effects of soft segment type and ion incorporation on the physical properties, surface properties, and plateled adhesion are discussed. The ionic polyurethaneureas exhibited poor phase separation, a smaller fraction of PTMO present at the surface, and a smaller contact angle. On the other hand, it also showed a larger fraction of PDMS present at the surface and a higher water absorption value than its nonionic counterpart. H-D-BD had more phase-separated structure, a larger fraction of PDMS present at the surface, and larger contact angle but lower water absorption value than the PTMO-containing polyurethaneureas. The in vitro platelet adhesion experiments indicated that the ionic groups, especially for carboxylate, and surface enrichment PDMS soft segment could effectively inhibit platelet adhesion.

Studies on thermotropic liquid crystalline polyurethanes. III. Synthesis and properties of polyurethane elastomers by using various mesogenic units as chain extender

Four series of thermotropic polyurethane elastomers (TPUEs) were synthesized in this study. The hard segments were formed by using 4,4′-methylenedicyclohexyl diisocyanate (H12MDI) reacted with various mesogenic units, such as benzene-1,4-di(4-iminophenoxy-n-hexanol), benzene-1,4-di(4-iminophenol), and 3,3′-(4,4′-biphenylene)dipropanol, which also acted as the chain extender. Poly(oxytetramethylene)glycols (PTMEGs), PTMEG-2000 (Mn 2,000) and PTMEG-1000 (Mn 1,000) were used as a soft segment. The structures of all synthesized thermotropic liquid crystalline polyurethanes (TLCPUs) were characterized by FTIR spectroscopy. The effects of mesogenic units on the LC properties and elastic behaviors of LCPUs were studied. It was difficult to show LC behaviors for the PU elastomers derived from the mesogenic units with a lower aspect ratio, such as 3,3′-(4,4′-biphenylene)dipropanol, or the long soft segments, PTMEG-2000. In addition, these PU elastomers show better elastic properties by using a higher aspect ratio mesogenic unit as the chain extender, such as benzene-1,4-di(4-iminophenoxy-n-hexanol and benzene-1,4-di(4-imino-phenol)). The thermal properties were investigated by DSC measurements, thermal optical polarized microscopy, wide angle X-ray diffraction, dynamic mechanical analysis, and thermogravimetric analysis. The mechanical properties were measured by a tensilemeter. © 1996 John Wiley & Sons, Inc.

Liquid‐crystalline polyurethanes, 4. Polyurethanes containing an azobenzene group in the side chain

AbstractPolyurethanes with azobenzene side groups attached via an alkyl spacer of different length were synthesized from N‐[4‐phenylazophenyl]‐ω‐[bis(2‐hydroxyethyl)amino]alkanamides (5) and equimolar amounts of diisocyanates such as hexamethylene diisocyanate (HDI), 4,4′‐methylenedicyclohexyl diisocyanate, 1,3‐cyclohexylenedimethyl diisocyanate, 2,4‐toluylene diisocyanate, and 4,4′‐methylenediphenyl diisocyanate. Polyurethanes obtained from diols 5 with HDI have a mesomorphic phase as determined by DSC and polarizing microscopy and are crystalline at room temperature as evidenced by X‐ray studies.