Fatty-acid-derived ester-urethane macromonomers synthesized using bismuth and zinc catalysts

Photocurable materials that can be delivered as liquids and rapidly (within seconds) cured in situ using UV light are gaining increased interest in advanced minimally invasive procedures. The aim of this work was to synthesize and characterize fatty-acid-derived ester-urethane telechelic (methacrylate) macromonomers, suitable for photopolymerization. The commonly used dibutyltin dilaurate catalyst was replaced with bismuth neodecanoate, bismuth tris(2-ethylhexanoate), and zinc (II) acetyloacetonate as less-toxic alternative catalysts. Additionally, ethyl acetate was used as a “green” solvent. The progress of the two-step synthesis was monitored with infrared spectroscopy. The chemical structure and molecular weight of the obtained viscous materials was characterized with nuclear magnetic resonance spectroscopy and gel permeation chromatography. Photocrosslinking of the macromonomers into elastomeric films was achieved using 150 s per spot of UV light (20 mW/cm2) exposure. Mechanical tensile testing of the films indicated their elasticity up to 120% and low modulus typical for soft and elastomeric materials. Finally, in vitro cytotoxicity tests showed high cell viability for the case of materials synthesized using bismuth and zinc catalysts. Overall, our results indicate that bismuth and zinc catalysts are excellent alternatives to organotin compounds in the synthesis of photocurable methacrylate ester-urethanes for potential biomedical applications.

Fatty-acid-derived ester-urethane macromonomers synthesized using bismuth and zinc catalysts

Minimally invasive surgical approaches require the development of new injectable materials. A particularly attractive strategy involves using photocurable materials that can be delivered as liquids and rapidly cured in situ using UV light. The aim of this work was to synthesize and characterize fatty-acid-derived ester-urethane telechelic (methacrylate) macromonomers, suitable for photopolymerization. The commonly used dibutyltin dilaurate catalyst was replaced with bismuth neodecanoate, bismuth tris(2-ethylhexanoate), and zinc (II) acetyloacetonate as less-toxic alternative catalysts. Additionally, ethyl acetate was used as a “green” solvent. The progress of the two-step synthesis was monitored with infrared spectroscopy. The chemical structure and molecular weight of the obtained viscous materials was characterized with nuclear magnetic resonance spectroscopy and gel permeation chromatography. Photocrosslinking of the macromonomers into elastomeric films was achieved using 150 s per spot of UV light (20 mW/cm2) exposure. Mechanical tensile testing of the films confirmed tensile strength and modulus values in a range of values typical of soft tissue. Finally, in vitro cytotoxicity tests showed high cell viability for the case of materials synthesized using bismuth and zinc catalysts. Overall, our results indicate that bismuth and zinc catalysts are excellent alternatives to organotin compounds in the synthesis of photocurable methacrylate ester-urethanes for biomedical applications, such as minimally invasive surgical protocols.

Synthesis and Characterization of Hyperbranched and Organosilicone Modified Waterborne Polyurethane Acrylates Photosensitive Resin

A new type of waterborne polyurethane acrylate was synthesized for use as a UV curing coating. The N,N-dihydroxy methyl ethyl-3-Methyl aminopropanoate monomer was first prepared via adding reactions of methyl acrylate and diethanol amine with methyl alcohol as the solvent. Then, the hyperbranched prepolymer was obtained by addition of trimethylolpropane with toluenesulfonic acid as catalyst and N,N-dimethyl formamide as solvent. The resulting hyperbranched and organosilicone modified waterborne polyurethane acrylates was synthesized through the mixed reaction of prepolymer and Hydroxy silicone oil, polyethylene glycol-1000, toluene diisocynate, dimethylolpropionic acid, 1,2-propylene glycol, hydroxyethyl acrylate, and triethylamine with dibutyltin dilaurate as the catalyst. The molecular structures were characterized by FT-IR and 1H NMR spectroscopy and GPC analysis and the thermal stability was studied by using TGA. Moreover, the influence of contemodnt of hydroxyl silicone oil, dimethylolpropionic acid, polyethylene glycol-1000, and prepolymer to various of properties such as glossiness, hardness, adhesive force, abrasion resistance, water absorption, elongation at break and tensile strength of films were analyzed. The temperature and catalyst dosage impact on percent conversion of isocyanate group (–NCO) were also studied. It was proven that the best dosage of hydroxyl silicone oil and dimethylolpropionic acid were 4.6%, the dosage of polyethylene glycol-1000 was 50%, and the amount of hyperbranched prepolymer was 0.5%, which could make the film achieve the optimum properties. The percent conversion of isocyanate group (–NCO) was maximum when reacting two hours at 80 °C with 0.2% catalyst.

Effects of Organic Solvent on Curing Behavior and Storage Stability for Waterborne Paint Containing Catalyst Encapsulated in Micelles

In this study, a 2-pack isocyanate curing waterborne paint (without organic solvents) encapsulating dibutyltin dilaurate (hereinafter, DBTL) in nonionic surfactant micelles with an hydrophilic–lipophilic balance of 13–14 in advance releases DBTL when the micelles are collapsed at 80 °C or higher, whereby the curing progresses rapidly. On the other hand, the viscosity levels of the paint before and after being left at 40 °C for 1 h are almost the same. Organic solvents are mandatory for waterborne paints to provide paint and film properties, but they might collapse the micelles when they are formulated in the paint. In this study, we investigate whether the abovementioned paint containing organic solvents can develop switching functionality in terms of maintaining the storage stability at 40 °C and expressing a catalytic function at 80 °C to progress the curing. As a result, we find that if the solubility of the organic solvent in water at 20 °C is at least 10 g/100 mL and the boiling point is ≤200 °C, both curing and storage stability can be achieved.

Thermal and anticorrosion properties of polyurethane coatings derived from recycled polyethylene terephthalate and palm olein-based polyols

Polyols of palm olein/polyethylene terephthalate (PET) were synthesized by means of incorporating recycled PET from waste drinking bottles in different proportions into palm olein alkyd in the presence of ethylene glycol. The polyols were characterized by FTIR, and theirs hydroxyl value (OHV), acid value (AV) and viscosity were determined. The formulation of the polyurethane coating was carried out by dissolving the polyol in mixed solvent of cyclohexanone/tetrahydrofuran (THF) (4 : 1) followed by reacting 1 hydroxyl equivalent of the polyol with 1.2 equivalents of methylene diphenyldiisocyanate and 0.05% dibutyltin dilaurate (DBTDL) catalyst. The coating cured through the cross-linking reactions between hydroxyl and isocyanate groups. The formation of urethane linkages was established by FTIR spectroscopy. The set films were characterized by thermal analysis. To study their anticorrosion properties, polarization measurements and EIS in 3.5% NaCl solution were determined. The coatings displayed good thermal stability and anticorrosion properties which were supported by XRD analysis. The PU7 coating, with the highest proportion of PET (up to 15% w/w), displayed significantly improved thermal stability and anticorrosion properties. It is evident that the performance of the polyurethane (PU) coatings could be enhanced by the incorporation of PET.

Characterization of Highly Filled Glass Fiber/Carbon Fiber Polyurethane Composites with the Addition of Bio-Polyol Obtained through Biomass Liquefaction

This work aims to investigate the process of obtaining highly filled glass and carbon fiber composites. Composites were manufactured using previously obtained cellulose derived polyol, polymeric methylene diphenyl diisocyanate (pMDI). As a catalyst, dibutyltin dilaurate 95% and Dabco® 33-LV were used. It was found that the addition of carbon and glass fibers into the polymer matrix causes an increase in the mechanical properties such as impact and flexural strength, Young’s modulus, and hardness of the material. Moreover, the dynamic mechanical analysis (DMA) showed a significant increase in the material’s storage modulus and rigidity in a wide range of temperatures. The increase in glass transition of soft segments can be noticed due to the limitation of macromolecules mobility in the material. The thermogravimetric analysis showed a four step decomposition, with maximal degradation rate at TmaxII = 320–330 °C and TmaxIII = 395–405 °C, as well as a significant improvement of thermal stability. Analysis of the material structure using a scanning electron microscope showed the presence of material defects such as voids, fiber pull-outs, and agglomerates of both fibers.

A Study on Making Rigid Polyurethane Foams from Vietnam Rubber Seed Oil-Based Polyol by Using Water as a Single Blowing Agent

In this work, for making rigid polyurethane foams, only water was used to serve as a blowing agent. Vietnam rubber seed oil-based polyol was also used. Following our previous research results, water content was fixed at 4 wt.% and glycerol content at 3 wt.%, as compared to biopolyol. The effect of the NCO/OH ratio, main catalyst (dibutyltin dilaurate), cocatalyst (triethylamine), and surfactant content as well as the surfactants on performances of foams was investigated through compressive strength, density, cell size, and size distribution. A suitable formulation for making foam by using biopolyol made from rubber seed oil was established. In parallel with it, foam based on commercial polyol derived from petroleum was also manufactured. The characteristics of the foaming process were assessed. The mechanical properties, thermal behavior, water absorption, and dimensional stability of foams were evaluated. The cellular morphology study shows that the cells of foam based on biopolyol were closed and rather uniform; however, cell size was 3% bigger and cell walls were also a bit thicker. The results showed that the properties of foam based on biopolyol were similar to those of petrofoams. This result may open a possibility to replace petropolyol with renewable biopolyol in foam fabrication.

Kinetic Features of Isophorone Diisocyanate and Oligoesterdiols Reaction under Waterborne Polyurethane Synthesis Conditions and the Preparation of the Polymer Dispersions

Kinetics of urethane formation from isophorone diisocyanate and polycaprolactone diol and poly(butylene adipate) in acetone was studied by IR spectroscopy. It was found that poly(butylene adipate) is the most reactive oligoesterdiol, with the reaction being both non-catalyzed and catalyzed by dibutyltin dilaurate. It was shown that the cycloaliphatic group of isophorone diisocyanate is an order of magnitude more active than the aliphatic one in catalytic reactions of isophorone diisocyanate with investigated oligoesterdiols. Furthermore, waterborne polyurethanes based on the studied oligoesterdiols were synthesized and characterized by DLS, DSC, and TGA methods.

Block Copolymers of Poly(ω-Pentadecalactone) in Segmented Polyurethanes: Novel Biodegradable Shape Memory Polyurethanes

In this report, the synthesis of poly(ω-pentadecalactone) (PPDL) (co)polymers and their incorporation into polyurethanes (PUs) are reported. Optimal conditions for the ring-opening polymerization (ROP) of ω-pentadecalactone (PDL) using dibutyltin dilaurate catalyst were established. For the synthesis of linear and crosslinked PUs, 50 kDa poly(ε-caprolactone) (PCL) and 1,6-hexamethylenediisocyanate (HDI) were used. The obtained polyurethanes were characterized by Attenuated Total Reflectance Fourier-Transform Infrared spectroscopy (AT-FTIR), differential scanning calorimetry (DSC), and dynamical mechanical analysis (DMA). The DMA of the selected sample showed a rubbery plateau on the storage modulus versus temperature curve predicting shape memory behavior. Indeed, good shape memory performances were obtained with shape fixity (Rf) and shape recovery (Rr) ratios.

Effect of Emulsifier on the Structure and Properties of Waterborne Silicone Antifouling Coating

Three-component waterborne silicone antifouling coatings, which could cured at room temperature, were prepared, respectively, with cationic (stearyl trimethyl ammonium bromide) or anionic (sodium dodecyl benzene sulfonate) silicone emulsion as a film-forming substance, γ-methacryloxypropyltrimethoxysilane as a curing agent and dibutyltin dilaurate as a catalyst. The effect of emulsifier on the structure and properties of silicone coating was studied. The results showed that the coating with cationic silicone emulsion had high crosslinking density, and its surface is smooth. The surface of the coating prepared by the anionic silicone emulsion is rough. Emulsifier type had no obvious effect on the surface free energy of the waterborne silicone coating. The coatings have the characteristics of low surface energy and excellent bacterial desorption properties. Stearyl trimethyl ammonium bromide in the cured coating can reduce the adhesion of marine bacteria on the coating surface. Both the emulsifiers can inhibit the activity of Navicula Tenera. The waterborne silicone coating prepared by cationic silicone emulsion has better comprehensive mechanical properties and antifouling performance.