Facile synthesis of waterborne UV-curable polyurethane/silica nanocomposites and morphology,physical properties of its nanostructured films

Waterborne UV-curable polyurethane (WUPU)/silica nanocomposites were prepared by in situ method using aqueous silica sol. SEM examinations of hybrid films indicated that the nanosilica were well dispersed in the matrix. Atomic force microscopy revealed that the microphase separation between polyurethane and silica was significantly affected by the amount of silica incorporated. DMA analysis showed that the nanocomposite films with silica nanoparticles showed a single tan δ peak, which implies that soft and hard segments of polyurethane are well phase mixed. The nanostructure films displayed enhanced storage modulus, tensile strength without sacrificing high elongation at break. The resulting transparent hybrid films are promising for a number of applications, e.g. for high performance water-based UV-curable coatings.     

纳米二氧化硅水溶胶改性UWPU的研究

通过丙酮法合成光固化水性聚氨酯丙烯酸酯预聚体,用三乙胺中和后在乳化过程中原位引入纳米二氧化硅水溶胶(Wv33、R900、R301)制备二氧化硅/光固化水性聚氨酯(SiO2/UWPU)纳米复合乳液,并进一步通过紫外光固化制备了SiO2/UWPU复合膜。通过电子扫描显微镜(SEM)和电子拉力机研究了不同纳米二氧化硅水溶胶对UWPU/SiO2复合膜的微观结构和力学性能的影响。SEM分析表明表面有机改性的pH值接近中性的硅溶胶(Wv33)较pH为酸性或碱性的硅溶胶在聚氨酯基体中有较好的分散性;应力-应变曲线分析表明Wv33能有效实现对复合膜的增强,即提高了复合膜的储存模量、拉伸强度和邵A硬度。     

Hydrophobic,transparent waterborne UV-curable polyurethane nanocomposites based on polycarbonate and PCL-PDMS-PCL reinforced with colloidal silica

Waterborne ultraviolet-curable polyurethane (WUPU) and its nanocomposites based on polycarbonate and α,ω-dihydroxy-[poly(ε-caprolactone)-poly(dimethylsiloxane)-poly(ε-caprolactone)] (PCL-PDMS-PCL) were synthesized using isophorone diisocyanate (IPDI), dimethyl propionic acid (DMPA), polycarbonate diol (PCD), PCL-PDMS-PCL, hydroxyethyl methacrylate (HEMA), and aqueous colloidal silica. The resulting WUPU materials were characterized by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopies, dynamic light scattering (DLS), and rheometry. The effects of PCL-PDMS-PCL and silica on the colloidal, physicochemical, and surface properties of the WUPU and its nanocomposites were studied. It was found that incorporation of PCL-PDMS-PCL (10 wt%) significantly enhanced the Young’s modulus, tensile strength, surface hydrophobicity, and water resistance of the WUPU films due to microphase separation and better interfacial adhesion between the PDMS soft phase and urethane hard phase provided by the PCL blocks. Furthermore, incorporation of silica (10 wt%) further improved the modulus, tensile strength, and water resistance of the PCD-PCL-PDMS-PCL-WUPU films without degrading the high surface hydrophobicity or transparency, due to the homogeneous dispersion and network structure of the silica clusters in the WUPU matrix.     

Preparation and properties of poly[styrene‐co‐(butyl acrylate)‐co‐(acrylic acid)]/silica nanocomposite latex prepared using an acidic silica sol

BACKGROUND: Polyacrylate/silica nanocomposite latexes have been fabricated using blending methods with silica nanopowder, in situ polymerization with surface‐functionalized silica nanoparticles or sol–gel processes with silica precursors. But these approaches have the disadvantages of limited silica load, poor emulsion stability or poor film‐forming ability. RESULTS: In this work, poly[styrene‐co‐(butyl acrylate)‐co‐(acrylic acid)] [P(St‐BA‐AA)]/silica nanocomposite latexes and their dried films were prepared by adding an acidic silica sol to the emulsion polymerization stage. Morphological and rheological characterization shows that the silica nanoparticles are not encapsulated within polymer latex particles, but interact partially with polymer latex particles via hydrogen bonds between the silanol groups and the ? COOH groups at the surface of the polymer particles. The dried nanocomposite films have a better UV‐blocking ability than the pure polymer film, and retain their transparency even with a silica content up to 9.1 wt%. More interestingly, the hardness of the nanocomposite films increases markedly with increasing silica content, and the toughness of the films is not reduced at silica contents up to 33.3 wt%. An unexpected improvement of the solvent resistance of the nanocomposite films is also observed. CONCLUSION: Highly stable P(St‐BA‐AA)/silica nanocomposite latexes can be prepared with a wide range of silica content using an acidic silica sol. The dried nanocomposite films of these latexes exhibit simultaneous improvement of hardness and toughness even at high silica load, and enhanced solvent resistance, presumably resulting from hydrogen bond interactions between polymer chains and silica particles as well as silica aggregate/particle networks. Copyright © 2009 Society of Chemical Industry     

Mechanical and dielectric properties of polyimide/silica nanocomposite films

Polyimide/silica (PI/silica) nanocomposite films were successfully prepared via in situ dispersive polymerisation and thermal imidisation. In order to obtain homogeneous nanoscale dispersibility and good compatibility with the PI matrix, hydrophobic aerosil was selected as the nanosilica precursor. 4,4-Bis(3-aminophenoxy)biphenyl (4,3-BAPOBP) was used as diamine to improve the processability of PI. The PI/silica nanocomposite films were characterised using Fourier transform infrared spectroscopy, scanning electron microscopy and differential scanning calorimetry. The mechanical and dielectric properties of the films were also measured. The results demonstrate that the tensile strength and breakdown strength of films can be markedly improved by the addition of appropriate amounts of silica to the PI matrix. At a silica content of 4.0?wt-%, the tensile strength and the breakdown strength of the films increased by 21 and 13%, respectively, compared with the neat PI. Thus, it is feasible to use nanosilica to improve the properties of PI.     

Film‐forming behavior and mechanical properties of colloidal silica/polymer latex blends with high silica load

In this article, silica sol (diameter: 8–100 nm) and polymer latex (T_g < 25°C) were mixed and dried at room temperature to prepare nanocomposite films with high silica load (≥50 wt %). Effects of silica size, silica load, and the T_g of the polymer on the film‐forming behavior of the silica/polymer latex blend were investigated. The transparency, morphology, and mechanical properties of the nanocomposite films were examined by UV–Vis spectroscopy, SEM, and nanoindentation tests, respectively. Transparent and crack‐free films were produced with silica loads as high as 70 wt %. Thirty nanometers was found to be the critical silica size for the evolution of film‐forming behavior, surface morphology, and mechanical properties. Colloidal silica particles smaller than this critical size act as binders to form strong silica skeleton. This gives the final silica/polymer nanocomposite film its porous surface and high mechanical strength. However, silica particles with sizes of 30 nm or larger tend to work as nanofillers rather than binders, causing poor mechanical strength. We also determined the critical silica load appeared for the mechanical strength of silica/polymer film at high silica load. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Mussel-inspired synthesis of silver nanoparticles as fillers for preparing waterborne polyurethane/Ag nanocomposites with excellent mechanical and antibacterial properties

Silver nanoparticles (AgNPs) were synthesized by a facile, mild and green method using dopamine as a reducing and stabilizing agent and were introduced to waterborne polyurethane (WPU) via an in situ emulsification method to prepare antibacterial nanocomposite films. The formation of AgNPs was characterized by UV–visible spectroscopy and XRD. The dispersion of AgNPs was confirmed by TEM and the thermal stability of WPU/Ag nanocomposites was confirmed by TGA. The results showed that AgNPs were uniformly dispersed in the WPU matrix. The introduction of AgNPs significantly improved the thermal stability of WPU films. With incorporation of 0.1 wt% AgNPs, a five-fold increase in the tensile strength was achieved without sacrificing the ultimate strain. The WPU/Ag nanocomposite films showed antibacterial activity against Escherichia coli and Staphylococcus aureus. © 2021 Society of Industrial Chemistry.     

Structure and dielectric properties of polyimide/silica nanocomposite nanofoam prepared by solid‐state foaming

In this article, polyimide (PI)/silica nanocomposite nanofoams were prepared by solid‐state foaming using supercritical CO₂ as foaming agent. To control the cell size and morphology of the PI/silica foam, the silica nanoparticles as nucleating agent were in situ formation from TEOS via sol‐gel process, which make the silica nanoparticles homogeneously dispersed in PI matrix. The resulting PI/silica nanocomposite nanofoams were characterized by scanning electron microscopy (SEM), the image analysis system attached to the SEM and dielectric properties measurements. In PI/silica nanocomposite nanofoams, one type of novel morphology was shown that each cell contained one silica nanoparticle and many smaller holes about 20–50 nm uniformly located in the cell wall. This special structure could visually prove that the nucleation sites during foaming were formed on the surface of nucleating agents. Compared with those of neat PI foam, the cell size of PI/silica nanocomposite nanofoams was smaller and its distribution was narrower. The dielectric constant of PI/silica nanocomposite nanofoams was decreased because of the incorporation of the air voids into the PI/silica nanofoams. While the porosity of PI/silica nanocomposite nanofoam film was 0.45, the dielectric constant of the film (at 1 MHz) was reduced from 3.8 to about 2.6. Furthermore, the dielectric constant of PI/silica nanofoam films remained stable across the frequency range of 1×10²～1×10⁷ H_Z. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42355.     

The effect of octamethylcyclotetrasiloxane (D4) addition on the structure and properties of film‐forming polyacrylate/silica core–shell composite particles

The film‐forming polyacrylate/silica core–shell nanocomposite particles with octamethylcyclotetrasiloxane (D₄) were successfully synthesized via aqueous emulsion polymerization in the presence of a glycerol‐functionalized nano silica sol. The ring‐opening polymerization of D₄ and the reaction with the glycerol‐functionalized nano silica particles before emulsion polymerization was the key procedure in this process. Transmission electron microscopy results showed that more nano silica particles tended to coat on the polyacrylate particles surface after the nano silica sols were modified with D₄. The silica aggregation efficiency was increased from 90.9 to 98.6% when the amount of D₄ used in the system was varied from 0 to 8.0 wt %. The transparency of the nanocomposite films was not compromised after D₄ was incorporated into the system. The films of the nanocomposite particles with or without D₄ both exhibited superior abrasive resistance. Furthermore, the water resistance and hydrophobicity of the films of these particles with D₄ were also improved significantly. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42003.     

水性光固化涂料研究进展

光固化水性涂料是一种新型环保涂料,它综合了传统UV固化技术和水性涂料技术的许多优点,近年来已成为非常活跃的研发领域。本文综述了水性光固化涂料的特点、组成、作用、基本性能,与传统油性光固化涂料相比,最突出的优点就是从根本上解决了传统光固化涂料硬度和柔韧性之间的矛盾。本文重点讨论了水性UV树脂、水性光引发剂的分类以及发展状况和研究进展,并介绍了水性光固化涂料的应用现状与发展趋势,同时指出了该技术存在的主要问题和改进方向。     

紫外光固化聚氨酯丙烯酸酯研究进展

综述丁紫外光（UV）固化聚氨酯丙烯酸酯的研究进展,主要包括：UV固化的聚氨酯丙烯酸酯预聚物;光固化有机／无机复合材料;水性UV固化聚氨酯丙烯酸酯和UV固化超支化聚氨酯丙烯酸酯。     

UV-curable polyurethane acrylate–Ag/TiO2 nanocomposites with superior UV light antibacterial activity

Polyurethane acrylate (PUA)–Ag/TiO₂ nanocomposites were synthesized through in situ polymerization. The well-dispersed Ag/TiO₂ nanorods serve as photoinitiator. Meanwhile, the PUA–Ag/TiO₂ nanocomposite films exhibit superior activity toward the photocatalytic degradation of Escherichia coli under UV light. The excellent UV curing and antibacterial activities can be ascribed to the synergistic effect of Ag and TiO₂, which promotes the effective electron/hole separation and thus generates various reactive species. Thin films with these nanoparticles are more hydrophilic after UV illumination. And the antibacterial mechanism of the UV-curable PUA–Ag/TiO₂ nanocomposites was proposed.     

Structure and properties of plasticized polyvinyl butyral‐silica nanocomposite films and test production of laminated glass using films

Plasticized polyvinyl butyral (PVB)‐silica nanocomposite films were formed by mixing PVB ethanol solution and silica sol, which was prepared from tetraethyl orthosilicate. The nanocomposite films were colorless and transparent even though the content of silica was 70 wt%. The glass transition temperature of PVB in the silica 2.5 wt% nanocomposites was higher by about 10°C than that of plasticized PVB. The PVB‐silica nanocomposite films were applied as an interlayer for laminated glass. The laminated glass made with the nanocomposite films containing less than 10 wt% silica showed good penetration resistance, not only at room temperature but also at 70°C. J. VINYL ADDIT. TECHNOL., 25:E59–E63, 2019. © 2018 Society of Plastics Engineers     

不同聚醚二元醇软段对光固化水性聚氨酯乳液性能的影响

以不同聚醚二元醇、异佛尔酮二异氰酸酯、2,2-双羟甲基丙酸、甲基丙烯酸-2-羟基乙酯为主要原料,通过丙酮法合成光固化水性聚氨酯(WPU)乳液,讨论了不同聚醚软段对光固化WPU乳液性能的影响.结果表明,由聚四氢呋喃醚二元醇PTMG1000和PTMG2000制备的光固化WPU乳液具有较小的粒径和粘度,其交联后的膜具有较高储...     

UV-curable waterborne polyurethane-acrylate: preparation, characterization and properties

The waterborne polyurethane-acrylate (PUA) oligomer was firstly prepared based on isophorone diisocyanate (IPDI), polyether polyol (NJ-210), dimethylol propionic acid (DMPA) and hydroxyethyl methyl acrylate (HEMA) via in situ and anionic self-emulsifying method. The UV-curable polyurethane-acrylate (UV-PUA) was obtained with oligomer, monomers (BA and TPGDA) and photoinitiator Darocur 1173. FT-IR, DSC and TGA were employed to investigate the structures and thermal properties of the UV-PUA films. The effects of BA/TPGDA (R) value, the content of Darocur 1173 and the UV curing time on the performances were investigated. Some mechanical performances, solvent resistance and the gel content of UV-PUA films were measured. When the ratio of BA/TPGDA was 5/5, the UV-PUA film had the best solvent (water, alkali and ethanol) resistances. Besides, with the ratio of the BA/TPGDA increasing, the surface drying time increased. When the content of Darocur 1173 was 4%, the gel content achieved the maximum while the surface drying time achieved the minimum. The obtained UV-curable polyurethane-acrylates are promising as oligomers for UV-curable coatings, plastics, inks and adhesives.     

Surface assisted laser desorption–ionization mass spectrometry on patterned nanoporous silica thin films

We describe the preparation and use of patterned nanocomposite silica thin films deposited on silicon for laser desorption-ionization mass spectrometry (LDI-MS) without the use of conventional matrices. Ordered nanocomposite silica thin films deposited on silicon substrates were prepared by evaporation induced self-assembly using Brij56 as the surfactant template. The films were then exposed to masked deep-UV light to selectively remove the template to yield isolated regions of ordered nanoporous silica in a field of nanostructured silica. The nanoporous regions act as isolated “wells” that allow for the mass spectral characterization of analytes by laser induced desorption–ionization MS using a commercial MALDI-TOF instrument. We demonstrate the utility of these patterned films for the mass spectral analysis of small organic molecules, such as amino acids, peptides and siderophores. No consistent background signal from the films was observed at laser intensities typically used to desorb/ionize analytes. We also show that the films remain active for over a year when stored at ambient laboratory conditions. Because these patterned nanocomposite films are straightforward to produce, readily modifiable and stable at ambient laboratory conditions, they provide a potentially useful alternative to currently available films and substrates for matrix-free LDI-MS analysis of small molecules.     

Iodine-loaded poly(silicic acid) gellan nanocomposite mucoadhesive film for antibacterial application

Iodine-loaded poly(silicic acid) gellan nanocomposite film was fabricated and evaluated for antibacterial properties. Poly(silicic acid) nanoparticles were synthesized by condensation of silicic acid under alkaline conditions in the presence of polyvinyl pyrrolidone, phosphate ions, and molecular iodine. The nanoparticles were incorporated into gellan dispersion to prepare gellan nanocomposite film using the solvent casting method. The nanocomposite films were characterized by Fourier transformed infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction studies. The results of characterization studies indicated improved thermal stability and an increase in the degree of crystallinity. The scanning electron micrographs and energy dispersive X-ray spectrum confirmed the uniform dispersion of silica and iodine in the nanocomposite films. The analysis of physical and mechanical properties revealed the enhanced tensile strength, moisture resistance, and higher folding endurance of poly(silicic acid) gellan nanocomposite films as compared to gellan film. Further, the iodine-loaded poly(silicic acid) gellan nanocomposite films showed good antibacterial activity against Staphylococcus aureus and Escherichia coli and effective mucoadhesive strength. The results indicate that iodine-loaded poly(silicic acid) gellan nanocomposite mucoadhesive film can be used for potential antibacterial applications in pharmaceuticals.     

Preparation and property of raspberry‐like AS/SiO2 nanocomposite particles

Surfactant‐free poly(acrylonitrile‐co‐styrene)/silica (AS/SiO₂) nanocomposite particles was synthesized in the presence of cheap, commercially amorphous aqueous silica sol at ambient temperature. Thermogravimetric analysis (TGA) indicated silica contents ranging from 5 wt % to 29 wt %, depending on reaction conditions. Particle size distributions and morphologies were studied using dynamic light scattering (DLS) and transmission electron microscopy (TEM), which clearly showed that most of the colloidal nanocomposites comprised approximately spherical particle with raspberry‐like morphology and relatively narrow size distributions. The optical clarity of solution‐cast nanocomposite films was assessed using UV–vis spectrometer, with high transmission being obtained over the whole visible spectrum. Differential scanning calorimetry (DSC) studies showed that the glass transition temperature of AS/SiO₂ nanocomposites can be higher than the corresponding pure AS, resulting from the hydrophilicity of the nanometer silica. The robustness and simplicity of this method may make large‐scale manufacture of this nanocomposite possible. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 415–421, 2007     

Mechanical properties and thermostability of polyimide/mesoporous silica nanocomposite via effectively using the pores

Series of polyimide (PI)/mesoporous silica nanospheres (MSNs) nanocomposite films with different contents of MSNs were successfully prepared via a simple wet impregnation method. The morphologies, microstructures, mechanical properties, transmittance, and thermal properties of the prepared PI and the PI/MSNs nanocomposite films were investigated in detail. As a result, the thermal stability and mechanical performances of PI were obviously improved by incorporating MSNs into PI. The tensile stress and Young's modulus of the nanocomposite film with 5 wt % MSNs were raised up to 97.65 MPa and 2220.06 MPa, which are greatly higher than the values of 82.51 MPa and 1440.86 MPa for the pure PI film. Experimental results confirmed that the designed polymerization tactic, which occurred in the pores of the MSNs, facilitated to enhance the mechanical and physical performances of the PI/MSNs nanocomposite films, and definitely induced better integration between organic matrix and inorganic nanofillers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41173.