Modification of polyurethane‐coated fabrics by sol–gel thin films

Sol–gel derived silica and hybrid films from tetraethoxysilane (TEOS) and 3‐glycidyloxypropyltrimethoxysilane (GLYMO) were deposited by dip‐coating, in order to find the best treatment. GLYMO‐based treatments preserved textile feel of the material. The coatings were characterized by infrared spectroscopy (IR), scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and water contact angle measurement. IR spectra confirmed the existence of silicate network and successfully conducted modification for both precursors. DSC and TGA showed that the conditions of hydrolysis had greater influence on TEOS than GLYMO‐based treatments. Both treatments shifted the degradation onset to higher temperatures. SEM images showed that polyurethane surface and pores were completely covered and filled by silica or hybrid thin films forming a composite organic–inorganic coating. Hydrophobic effect was preserved for all the samples, except for a single treatment of the GLYMO, due to its polar epoxy group. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39914.     

Synthesis and characterization of hybrid films from hyperbranched polyester using a sol–gel process

Hybrid organic/inorganic materials were prepared by an in situ sol–gel process using tetraethoxysilane (TEOS) in the presence of hyperbranched polyester. The influences of hyperbranched polyester molar mass as well as the amount of TEOS were examined. The condensation degree was characterized by solid state ²⁹Si NMR. The combination of solubility tests, calcination tests, SAXS and dynamic mechanical analysis allowed us to investigate the hybrid material nanostructure. The results show high compatibility between the inorganic silica phase and the organic polymer phase, due to the spherical shape of the hyperbranched polymer and its numerous hydroxyl groups. As a consequence, a continuous inorganic phase was formed even with a low silica precursor content without any macroscopic phase separation. These hybrid materials have a high T_g and high storage modulus even at an elevated temperature combined with improved thermal stability. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39830.     

Preparation and characterization of mesostructured polymer-functionalized sol–gel-derived thin films

The present study attempts to incorporate methacrylate-based polymers into ordered lamellar organic/inorganic nanocomposite films composed of alternating SiO₂/polymer layers. The films are prepared by dip-coating from a solution containing the monomers and silica precursors, thus leading to composite lamellar mesostructured materials through evaporation-induced self-assembly (EISA). A polymerizable coupling agent is added to covalently link the polymers to the silica matrix. The final polymer/SiO₂ hybrid material is obtained by a separate free-radical polymerization step, initiated by UV exposure or thermal treatment. Using trimethoxy(7-octen-1-yl)silane as a coupling agent, a procedure was established that preserved the mesostructure and maintained the swelling properties of the polymers, while acrylate-based coupling agents lead to a significant distortion of the film mesostructure. Structure and composition of the films were studied by X-ray diffraction, NMR and IR.     

Preparation and properties of cardanol‐based polybenzoxazine/SiO2 hybrids by sol‐gel technique

A new cardanol‐based benzoxazine monomer containing a hydroxyl group (CBZ) was synthesized and characterized by FT‐IR and ¹H NMR spectroscopy. The formation mechanism of cardanol‐based polybenzoxazine/SiO₂ hybrids from CBZ and tetraethoxysilane (TEOS) by sol‐gel technique was invested by FT‐IR analysis. FT‐IR and SEM confirmed that there were many SiO₂ particles formed and embedded in the cardanol‐based polybenzoxazine. A phase separation occurred when the ratio (wt) of TEOS to CBZ was not less than 3 : 5. TGA results illuminated the thermal stability and char yield of cardanol‐based polybenzoxazine could be enhanced due to the formation of SiO₂ particles in the polybenzoxazine matrix. Incorporation of SiO₂ could improve the surface de‐wetting and anti‐ultraviolet properties of the films. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and characterization of hybrid organic–inorganic epoxide‐based films and coatings prepared by the sol–gel process

Hybrid organic–inorganic coatings and free‐standing films were prepared and characterized. The hybrids were prepared from [3‐(glycidyloxy)propyl]trimethoxysilane, diethoxy[3‐(glycidyloxy)propyl]methylsilane, poly(oxypropylene)s of different molecular weights end‐capped with primary amino groups (Jeffamines D230, D400, and T403), and colloidal silica particles with hydrochloric acid as a catalyst for the sol–gel process and water/propan‐2‐ol mixtures as solvents. The structure evolution during the network formation was followed by NMR spectroscopy and small‐angle X‐ray scattering; the surface morphology was tested by atomic force microscopy. The influence of the reaction conditions (the organosilicon precursor, oligomeric amine, ratio of functional groups, and method of preparation) on the network buildup and product properties was studied and examined. The mechanical testing, based on stress–strain experiments, in combination with dynamic mechanical thermal analysis served as an effective instrument for the optimization of the reaction conditions for the preparation of products with desired properties. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 937–950, 2004     

Synthesis and characterization of novel polyimide/SiO2 nanocomposite materials containing phenylphosphine oxide via sol‐gel technique

In this article, a series of novel polyimide/silica (PI/SiO₂) nanocomposite coating materials were prepared from tetraethoxysilane (TEOS), γ‐glycidyloxypropyltrimethoxysilane (GOTMS), and polyamic acid (PAA) via sol‐gel technique. PAA was prepared by the reaction of 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA) and bis (3‐aminophenyl) phenyphosphine oxide (BAPPO) in N‐methyl‐2‐ pyrrolidone (NMP). BAPPO was synthesized hydrogenation of bis (3‐nitrophenyl) phenyphosphine oxide (BNPPO) in the presence of Pd/C. The silica content in the hybrid coating materials was varied from 0 to 20 wt %. The molecular structures of the composite materials were analyzed by means of FT‐IR and ²⁹Si‐NMR spectroscopy techniques. The physical and mechanical properties of the nanocomposites were evaluated by various techniques such as, hardness, contact angle, and optical transmission and tensile tests. These measurements revealed that all the properties of the nanocomposite coatings were improved noticeable, by the addition of sol‐gel precursor into the coating formulation. Thermogravimetric analysis showed that the incorporation of sol‐gel precursor into the polyimide matrix leads to an enhancement in the thermal stability and also flame resistance properties of the coating material. The surface morphology of the hybrid coating was characterized by scanning electron microscopy (SEM). SEM studies indicated that nanometer‐scaled inorganic particles were homogenously dispersed throughout the polyimide matrix © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation of siloxane–silsesquioxane hybrid thin films for large‐scale‐integration interlayer dielectrics with excellent mechanical properties and low dielectric constants

Several kinds of homogeneous organic–inorganic hybrid polymer thin films were designed with improved mechanical properties and low dielectric constants (<3.0). Novel soluble siloxane–silsesquioxane hybrid polymers were synthesized with cyclic and/or cage silane monomers, which had triorganosiloxy (R₃Si_1/2), diorganosiloxane (R₂SiO_2/2), and organosilsesquioxane (RSiO_3/2) moieties with ethylene bridges at the molecular level, by the hydrolysis and condensation of 2,4,6,8‐tetramethyl‐2,4,6,8‐tetra(trimethoxysilylethyl)cyclotetrasiloxane (a cyclic monomer). The electrical properties of these films, including the dielectric constant (～2.51), leakage current (6.4 × 10^?11 A/cm² at 0.5 MV/cm), and breakdown voltage (～5.4 MV/cm) were fairly good. Moreover, the mechanical properties of the hybrid films, including the hardness (～7 GPa), modulus (～1.2 GPa), and crack‐free thickness (<2 μm), were excellent in comparison with those of previous spin‐on‐glass materials with low dielectric constants. The excellent mechanical properties were proposed to be due to the high contents of Si? OH groups (>30%) and the existence of ethylene bridge and siloxane moieties in the hybrid polymer precursors. In addition, the mechanical properties of the hybrid films were affected by the contents of the cagelike structures. The more cagelike structures a hybrid film contained, the worse its mechanical properties were. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 626–634, 2003     

Preparation and characterization of high refractive index thin films of TiO2/epoxy resin nanocomposites

By using sol–gel method, amorphous titania was introduced into epoxy matrix to prepare a series of high refractive index TiO₂/epoxy resin nanocomposite films. To increase the refractive index of the hybrid films, triethoxysilane‐capped trimercaptothioethylamine (TCTMTEA), a new kind of high refractive index coupling agent was synthesized from trimercaptothioethylamine (TMTEA). In the experiment, TCTMTEA acted as the solidification agent together with TMTEA except being used as the coupling agent. The hybrid films have been characterized via FTIR, AFM, DSC, TGA, etc. The experimental results showed that the amorphous TiO₂ had been dispersed uniformly in the organic polymer matrix with the size smaller than 100 nm in each sample. More importantly, the refractive index of this kind of materials can be continuously adjusted from 1.61 to 1.797 with the content of TiO₂ increasing from 0% to 65% in mass, and the continuously adjusted refractive index is very important for the applications in optical antirefractive films. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1631–1636, 2006     

Synthesis and characterization of new anthracene‐based semiconducting polyethers

New anthracene‐based polyethers, anthracene/bisphenol A (An–BPA) and anthracene/fluorinated bisphenol A (An–BPAF), were synthesized and characterized. An–BPA and An–BPAF were fully soluble in common organic solvents and had number‐average molecular weights of 2580 and 3240, respectively. The optical properties of the polymers were investigated with ultraviolet–visible absorption and photoluminescence spectroscopy. Blue photoluminescence was observed in dilute solutions. In solid thin films, π–π interactions influenced the optical properties, and redshifted photoluminescence spectra were obtained; a green emission (504 nm) for An–BPAF and a green‐yellow emission (563 nm) for An–BPA were found. By cyclic voltammetry, the electrochemical band gap was estimated to be 2.72 and 3.05 eV for An–BPA and An–BPAF, respectively. Single‐layer diode devices of an indium tin oxide/polyether/aluminum configuration were fabricated and showed relatively low turn‐on voltages (3.5 V for An–BPA and 3.7 V for An–BPAF). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The dielectric properties and optical propagation loss of c-axis oriented ZnO thin films deposited by sol–gel process

The c-axis oriented ZnO thin films were prepared on various substrates by sol–gel processes. The stability of solution was examined through solvent and stabilizer. The c-axis orientation and grain size of films were increased with increasing of heat treatment temperature. The optical propogation losses of ZnO films deposited SiO₂/Si(111) substrates were measured using end-coupling method. The losses result in the scattering of the interface of ZnO/SiO₂, and the ZnO grain. Dielectric constant and resistivity of thin films deposited on Pt/SiO₂/Si(111) substrates are, respectively, in the range of 7–13 and 1.7×10⁴9.8×10⁵Ω cm.     

Synthesis and characterization of a kind of poly(3‐butylthiophene methine) with azo side groups

To enhance the third nonlinear optical properties of poly(thiophene methine), we synthesized a new kind of poly(3‐butylthiophene methine) with azo side groups: poly[(3‐butylthiophene‐2,5‐diyl)‐p‐(N,N‐dimethylamino)azobenzylidenequinomethane] (PBTDMABQ). PBTDMABQ and its intermediate product were characterized with IR, ultraviolet–visible, and ¹H‐NMR spectroscopy. The band gaps of PBTDMABQ were calculated to be 1.94 and 2.06 eV with two different models. The thermal stability, determined by thermogravimetric analysis, indicated that PBTDMABQ decomposed above 345°C. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1261–1265, 2005     

Tailoring of elastomeric grafted coating via sol–gel chemistry of crosslinked polymethylhydrosiloxane

Thin coating of crosslinked polymethylhydrosiloxane are grafted on silica using sol–gel process that leads to polymer layers tailored in term of thickness and elasticity. The degree of crosslinking is tuned by sol–gel polycondensation of a mixture of methyldiethoxysilane(DH) HSi(CH₃)(OCH₂CH₃)₂ and triethoxysilane (TH) HSi(OCH₂CH₃)₃, yielding triethoxysilane‐based networks. Samples with well‐defined thicknesses from nanometer to micrometer range are prepared by sol–gel dip‐coating method on silicon surface. Homogeneous or gradient‐thickness coating can be produced in this way. It results in surface‐attached networks bearing Si? H functionalities covalently anchored to the substrate. Powdered gels of DH/TH composition from 50/50 to 95/5 (mol %) were also prepared for a comparison purpose. The structure of the gels was investigated by NMR and FTIR, showing that DH/TH mixtures react totally to yield homogeneous matrix. The surface‐attached polymer films are very stable and present high hydrophobicity as evidenced by contact angle measurements. Their surface and mechanical properties have been qualitatively studied using the atomic force microscopy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1504–1516, 2007     

Characterization and properties of UV‐curable polyurethane‐acrylate/silica hybrid materials prepared by the sol‐gel process

UV‐curable, transparent hybrid material of urethane‐acrylate resin was prepared by the sol‐gel process using 3‐(trimethoxysilyl)propylmethacrylate (TMSPM) as a coupling agent between the organic and inorganic phases. The effects of the content of acid and silica on the morphology and mechanical properties of UV‐curable polyurethane‐acrylate/silica hybrid (UA‐TMSPM)/SiO₂ materials have been studied. The results of thermogravimetric analysis for the (UA‐TMSPM)/SiO₂ hybrid materials indicated that the thermal stability of the hybrids is greatly improved. It was found that with the increase of HCl content, the interfacial interaction between organic and inorganic phases had been strengthened, as demonstrated by field emission scanning electron microscopy. Without sacrificing flexibility, the hybrid materials showed improved hardness with increasing content of acid and silica. Compared with the pure organic counterpart UA/hexanediol diacrylate (UA/HDDA) system, abrasion resistance of the hybrids improved with increasing acid content, at low silica content. Copyright © 2004 Society of Chemical Industry     

Synthesis,characterization, electropolymerization,and possible utilities of a new ruthenium–thiophene complex

[RuCl₂(p‐cymene)]₂ was reacted with silver triflate and thiophene to give the sandwich complex [Ru(η⁵‐C₄H₄S)(η⁶‐p‐cymene)](PF₆)₂, which was characterized with NMR spectroscopy (¹H‐NMR, ¹³C‐NMR, and ³¹P‐NMR), Fourier transform infrared spectroscopy, elemental analysis, and cyclic voltammetry. The behavior of this new complex in dimethyl sulfoxide with regard to the amount of absorbed water was investigated by both NMR and cyclic voltammetry; the formation of other species that affected electropolymerization was demonstrated. However, under optimal working conditions (in an anhydrous medium), the complex was successfully immobilized on a platinum electrode via an electro‐oxidation pathway through the thiophene ligand. This generated a highly stable, electroactive polymer film. Its response to the doping–undoping (charge–discharge) and redox processes, added to its high stability, promises important applications for this novel material. Moreover, this opens up the possibility of testing other compounds, such as [Ru(η⁵‐thiophene)(η⁶‐arene)], that were previously synthesized and reported for their electropolymerization and use as sensors according to their redox properties. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43559.     

Preparation and characterization of thin films of the poly(p‐phenylene vinylene) semiconducting polymer

Conjugated polymers have been the subject of many studies because of their widespread applications in electronic and optoelectronic devices. Poly(p‐phenylene vinylene) is a leading semiconducting polymer in optical applications. This work is focused on the development of thin films of poly(p‐phenylene vinylene) by spin coating and their characterization with Fourier transform infrared spectroscopy, X‐ray diffraction, and scanning electron microscopy to understand their changes. An empirical model has been developed to show the effect of the variables—the spin speed, polymer concentration, and spin time—on the film thickness. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

SiO2 reinforced HDPE hybrid materials obtained by the sol–gel method

Novel high density polyethylene (HDPE)/SiO₂ hybrid materials were prepared by the sol–gel process using tetraethoxysilane (TEOS). HDPE and synthesized HDPE‐g‐vinyl trimethoxysilane (VTMS) through melt grafting method was used as the raw material. The structure and thermal, mechanical properties of hybrid materials were investigated by Fourier transform infrared (FTIR) spectroscopy, X‐ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), simultaneous thermogravimetric (TG), differential thermal analysis (DTA), and tensile tests, respectively. Silica phase in the HDPE‐g‐VTMS hybrids showed a network structure and nano‐scale size. The covalent bonds between organic and inorganic phases were introduced by the HDPE‐g‐VTMS bearing trimethoxysilyl groups, which underwent hydrolytic polycondensation with TEOS. The thermal stability and mechanical properties of HDPE‐g‐VTMS hybrids were obviously improved by embedded silica networks. It was found that the silica content in the HDPE‐g‐VTMS hybrid material was linearly increased with the TEOS dosage. The formation of the HDPE‐g‐VTMS hybrid was beneficial for enhanced mechanical strength and thermal stability, in comparison with the neat HDPE. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 39891.     

Preparation of titanium dioxide/polyacrylate nanocomposites by sol–gel process in reverse micelles and in situ photopolymerization

UV‐curable, transparent acrylic resin/titania organic–inorganic hybrid films were prepared by controlled hydrolysis of titanium tetrabutoxide in Span‐85/Tween 80 reverse micelles and the subsequent in situ photopolymerization of the acrylic monomers. UV–vis spectra and atomic force microscopy (AFM) indicated the presence of a nanoscale hybrid composition. The onset of absorption (λ_onset) of titania in the hybrids appeared between 363.4 and 383.5 nm, which exhibited blue shifts relative to that of bulk anatase (λ_onset = 385 nm). The titania content increased rapidly at higher temperature and higher TTB content, whereas it increased slowly with longer post‐thermal treatment times. The refractive index and UV shielding properties of the organic polymer were obviously improved with increasing titania content. AFM images showed the inorganic domains (mean size 25.3–28.8 nm) were uniformly dispersed in the polymeric networks. The roughness parameters of the hybrid material were: toughness, 1.5–2.3 nm; root mean square roughness, 4.5–4.6 nm; and peak and valley distance, 9.7–19.4 nm. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5105–5112, 2006     

Studying the mechanisms of titanium dioxide as ultraviolet‐blocking additive for films and fabrics by an improved scheme

Titanium dioxide (TiO₂) has good ultraviolet (UV)‐blocking power and is very attractive in practical applications because of such advantages as nontoxicity, chemical stability at high temperature, and permanent stability under UV exposure, for example. Development of nanoscience and ‐technology provides new ways for better treatment for UV‐resistant films and fabrics using TiO₂. However, the exact mechanisms of TiO₂ as a UV‐blocking additive are still not very clear, and researchers hold different views on this issue. The aim of this investigation was to study systematically the mechanisms of TiO₂ as a UV‐blocking additive for films and fabrics. To achieve this goal, the conventional scheme describing light interactions with fabrics was revised based on more recent progress in optical theory, and special experiments and analytic methods were used in the investigation. Several effects attributed to the nanoscale additives were identified. Moreover, detailed analyses based on the results yielded a few important suggestions useful in developing or improving both inorganic UV‐blocking agents and the UV‐protective films and textiles. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3201–3210, 2004     

Preparation and characterization of polyimide/Al2O3 hybrid films by sol–gel process

A sol–gel process has been developed to prepare polyimide (PI)/Al₂O₃ hybrid films with different contents of Al₂O₃ based on pyromellitic dianhydride (PMDA) and 4,4′‐oxydianiline (ODA) as monomers. FESEM and TEM images indicated that Al₂O₃ particles are relatively well dispersed in the polyimide matrix after ultrasonic treatment of the sol from aluminum isopropoxide and thermal imidization of the gel film. The dimensional stability, thermal stability, mechanical properties of hybrid PI films were improved obviously by an addition of adequate Al₂O₃ content, whereas, dielectric property and the elongation at break decreased with the increase of Al₂O₃ content. Surprisingly, the corona‐resistance property of hybrid film was improved greatly with increasing Al₂O₃ content within certain range as compared with pure PI film. Especially, the hybrid film with 15 wt % of Al₂O₃ content exhibited obviously enhanced corona‐resistance property, which was explained by the formation of compact Al₂O₃ network in hybrid film. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of nanocomposite of polyimide–silica hybrid from nonaqueous sol–gel process

Polyimide–silica (PI–SiO₂) hybrids with a nanostructure was obtained using the nonaqueous sol–gel process by polycondensation of phenyltriethoxysilane in a polyamic acid solution. Self‐catalyzed hydrolysis of phenyl‐substituted akoxysilane and modification on the polyimide structure are applied and result in highly compatible PI–SiO₂ hybrids. Transparent PI–SiO₂ with a high silica content of about 45% was thus obtained. The prepared PI–SiO₂ films were characterized by infrared spectrometry, ²⁹Si‐NMR, thermogravimetric analysis, differential scanning calorimetry, and scanning electron microscopy. These characterizations showed the silica influence on the properties of the hybrid. The thermal expansion coefficient of the PI–SiO₂ and the temperature correlation were also established for probing the potential for application. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1609–1618, 2000