Effect of preparation conditions on the thermal stability of an epoxy-functional inorganic-organic hybrid material system doped with Zr

An inorganic-organic hybrid material system consisting of (3-glycidyloxypropyl)trimethoxysilane, dimethyldimethoxysilane and zirconium(IV) n-propoxide was prepared by the sol-gel method. The influence of processing parameters including Zr content, UV irradiation and sol ageing on the thermal stability of the resultant thin films was characterised by thermogravimetry. It was demonstrated that the crosslinking of epoxy groups in the structure was the primary reason for variation in the thermal stability of the system. As Zr and/or UV irradiation may be employed to crosslink the epoxy groups in the structure, the thermal stability of the system can be tuned by the optimal combination of these two crosslinking methods.     

Effect of preparation conditions on the thermal stability of an epoxy-functional inorganic-organic hybrid material system with phenyl side group

A hybrid material system consisting of (3-glycidyloxypropyl)trimethoxysilane and dimethyldimethoxysilane as matrix materials and diphenyldimethoxysilane (DPDMS) as both a matrix material and a potential thermal stabiliser by the sol-gel method. A detailed thermogravimetric analysis study of the influence of processing parameters, including DPDMS content, UV irradiation and sol ageing, on the thermal stability of the resultant thin films was presented. FT-IR spectroscopy was used to monitor the changes in the relative amount of epoxy rings in the system during processing. It was demonstrated that the crosslinking of epoxy groups in the structure is the primary reason for changes in the thermal stability of the system. It was also shown that the thermal stability, in terms of 10% mass loss, of the material system could be improved up to 280 °C, by adjusting the preparation conditions, compatible with several subsequent high temperature optoelectronic integration processes.     

UV stability of HMS-PP (high melt strength polypropylene) obtained by radiation process

HMS-PP in grains was synthesized by the gamma irradiation of PP under a crosslinking atmosphere of acetylene, followed by thermal treatment for radical recombination and thermal treatment for annihilation of the remaining radicals. The UV stability of the material was evaluated in pellet form. The accelerated weathering test of HMS-PP samples were performed under artificial ultra-violet light and in a condensation chamber Comexim (C-UV type) apparatus with UV exposure for 120 and 240 h. The results were compared to those from ageing caused by sunlight and dew under natural exposition. This work investigated changes in mechanical proprieties (elongation and rupture strength), Fourier transform infrared spectroscopy (FTIR), optical microscopy (MO), scanning electron microscopy (SEM) and rheological properties of HMS-PP after the UV ageing. We find that the HMS-PP has more degradation than regular PP and undergoes predominate chain scission in aggressive UV ageing conditions.     

Effect of UV irradiation on the physico-chemical properties of iron crosslinked collagen

Collagen is the main component of connective tissue and finds immense applications as a biomaterial. In this study, effect of UV irradiation on collagen crosslinked with iron has been carried out. The physical and optical properties of crosslinked collagen affected by UV irradiation were analyzed using electrospectral and fluorescence studies. The electronic spectral studies showed that the photoproducts formed on UV radiation decrease in the presence of iron. Circular dichroic studies revealed that the conformational changes brought about in the protein due to UV irradiation have been reduced owing to the crosslinking with iron. However, prolonged irradiation does bring about conformational changes to the protein.     

Ultraviolet-radiation-curing of an organically modified silicate-based material system with epoxy functionality,and the role of titanium

An organically modified silicate-based material system with epoxy functionality was synthesised by the sol–gel method using some certain Si- and Ti-alkoxide precursors. The resultant system was processed with ultraviolet (UV)-radiation. Influences of certain synthesis and process parameters, including Ti content, sol ageing time, and UV-irradiation time, on various properties of the system were detailed. Overall results demonstrated that Ti-based precursors and UV-radiation could be employed to modify the microstructure, and that the final properties of the system might be tuned by an optimal combination of these two parameters. This preliminary study therefore revealed that this technique described herein might be used to develop a new process regime to obtain materials of this type with desired properties.     

Photo-optical properties of photopolymerizable cholesteric compositions

Compositions consisting of nematogenic diacrylate monomer and chiral dopants capable of forming the cholesteric mesophase and of photopolymerizing were obtained and studied. For the first time, the change of optical properties and cholesteric helix pitch during photocrosslinking of diacrylate under UV irradiation (365 nm) was investigated. The kinetics of photopolymerization was studied and several stages of this process were observed. Cholesteric photopolymerizable blends containing chiral photosensitive dopant capable of E–Z isomerizing under UV irradiation (313 nm) were studied. The decrease of the helix twisting power of the dopant during photoisomerization was observed resulting in untwisting of the helix and shift of the selective light reflection peak into the long-wavelength region of the spectrum. The possibility of the photoregulation of optical properties of such blends with following fixation of structure and of these properties by means of photopolymerization under UV irradiation (365 nm) was demonstrated.     

Doubly patternable epoxy based sol–gel structures by UV and soft lithography

The sol–gel synthesis of hybrid materials offers special opportunities to combine polymer and glass properties and to create promising candidates for photonic applications.We report on the optical and morphological characterization of a new photosensitive epoxy based sol–gel system. Germanium ethoxide and 3-Glycidoxypropyltrimethoxysilane were used as precursors for hybrid sol-gel planar coatings. A photoacid generator was added to solution in order to allow the epoxy photopolymerization when the films are selectively exposed to UV light. The refractive index increase (Δn = 0.015) induced by UV light allows the direct patterning of waveguiding structures having good morphological quality. Stripes and beam splitters were defined by direct UV exposition on silicon substrates. Moreover, we present structures made by thermal imprinting method. Silicon masters have been used to transfer relief gratings on the photopolymerizable epoxy sol-gel materials. Combining thermal imprinting technique and UV light exposition through a photomask, complex structures can be realized such as light couplers, sensors and wavelength filters.     

Modification of new polymer materials based on aminostyrene by irradiation

The ultra-violet (UV) irradiation induced modification of the mechanical and optical properties of several polymer composites containing 4-aminostyrene and glycidyl methacrylate and their dependences on radiation dose, structure and ageing have been investigated. The nano- and microindentation techniques were used for determination of the mechanical parameters of as-grown and irradiated materials. The light-induced structural changes result in an increase of the hardness and elastic modulus of the polymer layers up to five and three times, respectively. It is also shown that the influence of polymer structure is significant. The conditions for improvement, degradation and stabilization of physical properties by UV irradiation were established. Load and depth sensing indentation has proved to be a powerful tool for an accurate estimation of mechanical properties of cross-linking polymer compositions. Variable-energy positron annihilation spectroscopy (slow-positron beam technique) was developed to measure defect depth profiles in the near-surface region. The increase of S-parameter with the increase of nano-hardness and elastic modulus has been determined for these materials.     

The maleimide modified epoxy resins for the preparation of UV‐curable hybrid coatings

In the present study, maleimide‐modified epoxide resin containing UV‐curable hybrid coating materials were prepared and coated on polycarbonate substrates in order to improve their surface properties. UV‐curable, bismaleimide‐modified aliphatic epoxy resin was prepared from N‐(p‐carboxyphenyl) maleimide (p‐CPMI) and cycloaliphatic epoxy (Cyracure‐6107) resin. The structure of the bismaleimide modified aliphatic epoxy resin was analyzed by FTIR and the characteristic absorption band for maleimide ring was clearly observed at 3100 cm^?1. Silica sol was prepared from tetraethylorthosilicate (TEOS) and methacryloxy propyl trimethoxysilane (MAPTMS) by sol–gel method. The coating formulations with different compositions were prepared from UV‐curable bismaleimide‐based epoxy oligomer and sol–gel mixture. The molecular structure of the hybrid coating material was analyzed by ²⁹Si‐CP/MAS NMR spectroscopy techniques. In the ²⁹Si CP/MAS NMR spectrum of the hybrid coating, mainly two kinds of signals were observed at ?68 and ?110 ppm that correspond to T³ and Q⁴ peaks, respectively. This result shows that a fully condensed structure was obtained. The thermal and morphological properties of these coatings materials were investigated by using TGA and SEM techniques. Hardness and abrasion resistance properties of coating materials were examined and both were found to increase with sol–gel precursor content of the coating. The photopolymerization kinetics was investigated by using RT‐IR. 70% conversion was attained with the addition of 15 wt% of BMI resin into the acrylate‐based coating formulation. It was found that the UV‐curable organic–inorganic hybrid coatings improved the surface properties of polycarbonate. Copyright © 2009 John Wiley & Sons, Ltd.     

Sol-Gel Synthesis of Hybrid Organic-Inorganic Monoliths Doped with Colloidal CdSe/ZnS Core-Shell Nanocrystals

Colloidal CdSe/ZnS core-shell nanocrystals, with a narrow size distribution, were dispersed in a hybrid sol resulting from the hydrolysis of tetraethylorthosilicate and 3-glycidoxypropyltrimethoxysilane (GLYMO). In order to reduce the gelation time and the exposure of the nanoparticles to air, several catalysts of the GLYMO epoxy ring opening were employed for the sol preparation, such as imidazole, methyl-imidazole, pyridine, benzylamine, propylamine. The role of the various catalysts was monitored by optical absorption measurements in the near infrared region, by observing the evolution of the epoxy bands. Imidazole was found to provide the fastest gelation and the best results in terms of bubble disappearance from the gel structure. The variation in the optical properties of the semiconductor nanoparticles embedded in the matrix was monitored as a function of the gelation time and was compared to the optical absorption and photoluminescence spectra of the nanoparticles dissolved in a chloroform solution. A decrease in the gelation-time results in a closer resemblance between the optical properties of the CdSe/ZnS doped monoliths and those of the particles dissolved in the solvent, before incorporation in the matrix. The photoluminescence of the CdSe/ZnS nanocrystals is not bleached after they are trapped in the glassy matrix.     

Adhesion of acrylate-based water dispersion to polypropylene hybrid fabrics

The increase in the content of crosslinking agent and surfactant in acrylate-based water dispersion results in an increase of surface parameters e.g. total SFE and its polar component, interfacial and mechanical work of adhesion of polyacrylate to PP hybrid fabrics. UV irradiation of polyacrylate coating in the course of accelerating ageing has the same effect on surface and adhesive properties as a crosslinking agent or surfactant and leads to a considerable growth of the total SFE, its polar component, interfacial and mechanical work of adhesion. The increase in the interfacial and mechanical work of adhesion with the increase of the crosslinking agent and/or surfactant content in acrylate-based water dispersion is higher for PES/PP fabrics compared to the PA/PP system. The adhesive properties of the film obtained from acrylate-based water dispersion are substantially influenced by the presence of a surfactant and a crosslinking agent.     

Photocatalytic Inactivation Efficiency of Anatase Nano-TiO2 Sol on the H9N2 Avian Influenza Virus

This study was conducted to investigate efficiency of TiO₂nanomaterial as a novel environment-friendly disinfectant to control avian influenza (AI) by its photochemical sterilization ability. Anatase nano-TiO₂sol, a neutral, viscous aqueous colloid of 1.6% TiO₂, was synthesized from peroxotitanic acid solution according to the Ichinose method. Transmission electron microscope images showed that the TiO₂particles were spindle-shaped with an average size of 50 nm. X-ray diffraction patterns revealed that the crystal phase of TiO₂particles was anatase type with photocatalytic effect. A photocatalytic film of nano-TiO₂sol was tested as a means of inactivating H₉N₂avian influenza virus (AIV). Inactivation capabilities were examined with 365 nm ultraviolet (UV) radiation under black light by adjusting the UV intensity, the UV irradiation time and the quantity of AIV. The titer change of AIV was determined by hemagglutination tests. Cytopathic effect of Madin Darby canine kidney (MDCK) cells was monitored by inverted fluorescence microscope. The results showed that anatase nano-TiO₂sol significantly inactivated AIV under UV irradiation of 365 nm. The inactivation of AIV viruses reached up to 100%. Therefore, anatase nano-TiO₂sol is a potentially environment-friendly antivirus agent to prevent AI.     

溶胶凝胶法制备CNT／ZnO纳米复合材料及其光催化性研究

Chemistry and Chemical Engineer School, Henan Institute of Science and Technology, Xinxiang, Henan 453003, China     

Effects of different light irradiations on structure and optical properties of methoxy-substituted tetraphenylporphyrins

UV lamp, filtered halogen lamp (at 425 nm) and Green laser (532 nm) experiments on a series of meso-substituted tetra phenyl porphyrin, TPP, bearing methoxy peripheral groups together with a metal derivate of 3,4 dimethoxy TPP were lead to different protonation and aggregation structures. Properties of irradiated porphyrins were investigated using their absorption and emission spectra in dichloromethane solution. The results show that the optical properties of the TPP derivates depend on light irradiation source, which shows the tuning of the absorption and emission spectra of the TPP derivates. From the dynamic light scattering measurements, the size distribution of samples was estimated about 5–15 nm in solvent after irradiation. Atomic force microscopy images of deposited porphyrins on the glass surface were shown average particle size between 10 and 30 nm. Particularly, self-assembly of the porphyrin derivates was also observed when green laser was used. We suggest that the irradiation source plays an important role in the controlling of size and morphology of products, and we propose a self-organization model to explain the formation of the porphyrin nanostructures.     

Synthesis and healing properties of poly(arylether sulfone)–poly(alkylthioether) multiblock copolymers containing disulfide bonds

Thermoplastic elastomers composed of soft and hard segments are important elastic and processable synthetic polymers. The microphase‐separated soft domains show low glass transition temperature and possess sufficient chain mobility at room temperature. In this study, we report the synthesis and healing properties of multiblock copolymers containing disulfide bonds as dynamic covalent bonds. The multiblock copolymers composed of poly(arylether sulfone) and poly(alkylthioether) segments were synthesized by oxidative coupling polymerization of the corresponding thiol‐terminated oligomers. Atomic force microscopy phase images, differential scanning calorimetry, and dynamic mechanical analysis curves indicated the microphase‐separated morphology of the multiblock copolymer. Self‐healing properties of the polymer were evaluated by changes in the elongation at break of the cut/adhered samples. The elongation recovery increased with UV irradiation time, and the multiblock copolymer showed a 93% recovery after UV irradiation for 5 h. The healing efficiency induced by UV irradiation, determined by subtracting the recovery without UV irradiation, was calculated to be 51%. According to the UV spectra and solubility changes after UV irradiation, the main healing factor in this study was the crosslinking reactions caused by thiyl radicals generated from UV irradiation instead of disulfide exchange reactions. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3545–3553     

Network formation of a phenyl vinyl ketone copolymer with 4-vinylbenzil and its photodecrosslinking in films

The irradiation (λ > 400 nm) in air of a copolymer of phenyl vinyl ketone with 4-vinylbenzil (VBZ) containing 1.5 wt % VBZ structural units in film, followed by the thermal decomposition of the resulting pendant benzoyl peroxide groups, leads to crosslinking. The subsequent irradiation of the crosslinked polymer at 366 nm results in the cleavage of the poly(phenyl vinyl ketone) chain between the junction points of the polymer network through a Norrish type II reaction. Therefore, poly(phenyl vinyl ketone-co-4-vinylbenzil) represents a novel type of photoresist based on polymer network decrosslinking. The process involves three steps: photogeneration of peroxide, crosslinking by its thermal decomposition, and subsequent photodecrosslinking of the polymer network. This material provides positive-tone images after UV exposure (λ > 330 nm) and development in an organic medium such as isopropyl methyl ketone. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 765–771, 2004     

Radiochemical ageing of epoxy coating for nuclear plants

The degradation of an epoxy-amine network exposed to gamma irradiation in oxygen atmosphere has been studied by using a variety of analytical methods, including infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and sol–gel analysis. Results show that the oxidation of epoxy systems grows with the irradiation dose. Hydroperoxides, which are species resulting from oxidation, were identified and quantified by DSC. As indicated by the sol–gel analysis, the mechanism of degradation of chain scission seems to be predominant over crosslinking. The modifications induced by irradiation reflect in a greater capacity of water absorption.     

Cross-linking assessment after accelerated ageing of ethylene propylene diene monomer rubber

The ageing of filled and cross-linked ethylene propylene diene elastomer (EPDM) has been studied under accelerated UV irradiation (λ ≥ 290 nm) at 60 °C, thermal ageing at 100 °C and in nitric acid vapours for different time intervals. Hardness measurements were performed. DSC-thermoporosimetry was used to estimate the mesh size distribution and cross-linking densities for each ageing. The development of functional groups was monitored by ATR spectroscopy. An increase in oxidation with exposure time after the different types of ageing was observed. The thermal stability of EPDM was assessed by TGA and evolved volatile gases were identified using FTIR spectroscopy.     

Influence of laser irradiation on the optical properties of nano-sized powder of metal oxide

ZnO Nano powders were prepared by co-precipitation method which includes post-oxidation and annealing in air. Influence of laser irradiation was carried out using 355 nm laser on the physical properties of ZnO nanoparticles. SEM studies reveal agglomeration of grains resulting into enlargement and deformation of the nanoparticles. XRD pattern exhibited decrease in FWHM which is a clear evidence of the increase in crystallite size due to laser irradiation. Optical properties showed decrease in the band gap of the laser irradiated Nano powders. The observed results indicated the UV laser irradiation increases the ZnO nanoparticles crystallinity that affects the optical properties of the ZnO.     

The optical properties of nanodisperse silica in hydrothermal solutions

The optical properties of aqueous solutions of colloidal silica were studied by photon correlation spectroscopy and spectrophotometry. Photon correlation spectroscopy measurements were taken at a 633 nm wavelength of monochromatic laser radiation. Autocorrelation function and scattered light amplitude plots were constructed, and the mean radii and diffusion coefficients of particles were determined. Spectrophotometric measurements were taken over the electromagnetic radiation wavelength range 200–1000 nm. The positions of optical density maxima were determined. The influence of various factors, including concentration, the size of nanoparticles, temperature, and pH, on the optical properties of aqueous solutions of silica was estimated.