Preparation and characterization of TiO2 and polymer nanocomposite films with high refractive index

Novel nanocomposite films of TiO₂ nanoparticles and hydrophobic polymers having polar groups, poly (bisphenol‐A and epichlorohydrin) or copolymer of styrene and maleic anhydride, with high refractive indices, high transparency, no color, solvent‐resistance, good thermal stability, and mechanical properties were prepared by incorporating surface‐modified TiO₂ nanoparticles into polymer matrices. In the process of preparing colloidal solution of TiO₂ nanoparticles, severe aggregation of particles can be reduced by surface modification using carboxylic acids and long‐chain alkyl amines. These TiO₂ nanoparticles dispersed in solvents were found not to aggregate after mixing with polymer solutions. Transparent colorless free‐standing films were obtained by drying a mixture of TiO₂ nanoparticles colloidal solution and polymer solutions in vacuum. Transmission electronic microscopic studies of the films suggest that the TiO₂ nanoparticles of 3–6 nm in diameter were dispersed in polymer matrices while maintaining their original size. Thermogravimetric analysis results indicate that the nanocomposite film has good thermal stability and the weight fraction of observed TiO₂ nanoparticles in the film is in good accordance with that of theoretical calculations. The refractive index of nanocomposite films of TiO₂ and poly(bisphenol‐A and epichlorohydrin) was in the range of 1.58–1.81 at 589 nm, which linearly increased with the content of TiO₂ nanoparticles from 0 to 80 wt %. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

A novel route for the synthesis of poly(2‐hydroxyethyl methacrylate) grafted TiO2 nanoparticles via surface thiol‐lactam initiated radical polymerization

Hybrid nanocomposites of poly(2‐hydroxyethyl methacrylate) (PHEMA) and TiO₂ nanoparticles were synthesized via surface thiol‐lactam initiated radical polymerization by following the grafting from strategy. Initially, TiO₂ nanoparticles were modified by 3‐mercaptopropyl trimethoxysilane to prepare thiol functionalized TiO₂ nanoparticles (TiO₂? SH). Subsequently, surface initiated polymerization of 2‐hydroxyethyl methacrylate was conducted by using TiO₂? SH and butyrolactam as an initiating system. The anchoring of PHEMA onto the surface of TiO₂ nanoparticles was investigated by FTIR, ¹H‐NMR, XPS, TGA, and XRD analyses. The experimental results indicated a strong interaction between PHEMA and TiO₂ nanoparticles owing to covalent bonding. The TEM and SEM images of PHEMA‐g‐TiO₂ showed that the agglomeration propensity of TiO₂ nanoparticles was significantly reduced upon the PHEMA functionalization. The molecular weight and polydispersity index of the cleaved PHEMA from the surface of TiO₂ nanocomposites were estimated by GPC analysis. An improved thermal property of the nanocomposites was observed from TGA analysis. PHEMA‐g‐TiO₂ nanocomposites were found to be highly dispersible in organic solvents. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Flame retardant polyurethane elastomer nanocomposite applied to coal mines as air‐leak sealant

Polyurethane elastomer (PUE) was firstly applied to mining coal roadway as air‐leak sealant. It is very important for air‐leak sealants to possess the super mechanical properties and good flame retardant performance when applied to the coal‐rock mass with cracks. The reinforced and toughened PUE nanocomposites were obtained by adding surface modified TiO₂ and SiO₂ nanoparticles. The modified PUE was characterized in terms of morphology, structure, and thermal stability by field‐emission scanning electron microscopy (FESEM), X‐ray diffraction (XRD), infrared spectroscopy (IR), and thermogravimetric analysis (TGA). Its flame‐retardant performance and mechanical properties were also tested. The results showed that the surface modified nanoparticles were uniformly dispersed in the PUE matrix and enhanced its thermal stability and flame retardant performance. The dual effects of uniform dispersion of nanoparticles and hydrogen bonding between nanoparticles and PUE improved the mechanical properties of the composites. The PUE modified by nanoparticles was successfully applied to coal mines and showed great air‐leak sealing effect. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

The Inhibitory Effect of Gallic Acid Alkyl Esters on Lipid Oxidation of Intactly Soaked Oyster Meats and Oyster Meat Homogenates during Refrigerated Storage

In this study, the antioxidant effects of gallic acid (GA) and its alkyl esters including methyl gallate (MG), butyl gallate (BG), octyl gallate (OG), and lauryl gallate (LG) in whole oyster meats and oyster meat homogenates during cold storage are investigated. The oxidation degree of lipid is measured by peroxide value (POV), thiobarbituric acid active substances (TBARS), and polyunsaturated fatty acid (PUFA) percentage. The results show that the lipid oxidation in the two types of samples is inhibited by GA alkyl esters, and the antioxidant effects first increase and then decrease along with the extension of the chain length, among the esters, BG and OG are relatively more effective. Therefore, it is speculated that the antioxidant capacity of GA alkyl esters may be influenced by hydrophobicity and follows a “cut-off effect” in whole oyster meats and oyster meat homogenates. Practical application: Seafood is easily oxidized even under cold storage because it contains more PUFA. Antioxidants are widely used to inhibit lipid oxidation. In this study, the antioxidant capacity of GA alkyl esters in whole oyster meats and oyster meat homogenates is investigated, which improves the selection of suitable antioxidants to strengthen the oxidation stability of oyster samples for cold storage.     

Annealing‐promoted unidirectional migration of organic‐modified nanoparticles embedded two‐dimensionally in polymer thin films

The spatial structures of oleic acid‐modified CeO₂ nanoparticles in polystyrene (PS) thin films spin‐coated on silicon substrates were observed by transmission electron microscopy, when the films underwent thermal annealing above the glass‐transition temperature of PS. Before annealing, the nanoparticles have segregated to the surface of the films, and formed two‐dimensional spatial structures in the PS films. Then, the nanoparticles migrated away from the film surface to the substrate/film interface during thermal annealing, maintaining the two‐dimensional spatial structures. In addition, we demonstrated that such unidirectional migration of nanoparticles across the PS film occurs regardless of the characteristics of the substrate surface, the concentration of nanoparticles, and the thickness of the films. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42760.     

Solid‐phase photocatalytic degradation of polystyrene with TiO2/Fe(St)3 as catalyst

A novel photodegradable TiO₂‐Fe(St)₃‐polystyrene (TiO₂‐Fe(St)₃‐PS) nanocomposite was prepared by embedding TiO₂ and Fe(St)₃ into the commercial polystyrene. Ferric stearate was added into polymer as cocatalyst in order to improve the dispersion in polystyrene and photocatalytic efficiency of TiO₂ nanoparticles. Solid‐phase photocatalytic degradation of the TiO₂‐Fe(St)₃‐PS nanocomposite was carried out in an ambient air at room temperature under ultraviolet lamp. The properties of TiO₂‐Fe(St)₃‐PS composite film were compared with that of the pure PS film and the TiO₂‐PS composite film, through weight loss monitoring, scanning electron microscope, gel permeation chromatogram, and FTIR spectroscopy. The photodegradation efficiency of TiO₂‐Fe(St)₃‐PS composite film was higher than that of the pure PS film and the TiO₂‐PS composite film under the UV light irradiation. The average molecular weight (M_w) of TiO₂‐Fe(St)₃‐PS composite film decreased 63.08%, and the number of average molecular weight (M_n) decreased 79.49% after UV light irradiation for 480 h. Photo‐oxidation leads to an increase in the low molecular weight fraction by chain scission, thereby facilitating biodegradation. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Mechanical properties and nonisothermal crystallization kinetics of polyamide 6/functionalized TiO2 nanocomposites

Titanium dioxide (TiO₂) nanoparticles were pretreated with excessive toluene‐2,4‐diisocyanate (TDI) to synthesize TDI‐functionalized TiO₂ (TiO₂‐NCO), and then polymeric nanocomposites consisting of polyamide 6 (PA6) and functionalized‐TiO₂ nanoparticles were prepared via a melt compounding method. The interfacial interaction between TiO₂ nanoparticles and polymeric matrix has been greatly improved due to the isocyanate ( NCO) groups at the surface of the functionalized‐TiO₂ nanoparticles reacted with amino groups ( NH₂) or carboxyl ( COOH) groups of PA6 during the melt compounding and resulted in higher tensile and impact strength than that of pure PA6. The nonisothermal crystallization kinetics of PA6/functionalized TiO₂ nanocomposites was investigated by differential scanning calorimetry (DSC). The nonisothermal crystallization DSC data were analyzed by the modified‐Avrami (Jeziorny) methods. The results showed that the functionalized‐TiO₂ nanoparticles in the PA6 matrix acted as effective nucleation agents. The crystallization rate of the nanocomposites obtained was faster than that of the pure PA6. Thus, the presence of functionalized‐TiO₂ nanoparticles influenced the mechanism of nucleation and accelerated the growth of PA6 crystallites. POLYM. COMPOS., 35:294–300, 2014. © 2013 Society of Plastics Engineers     

Spectroscopic study of film formation from polystyrene latex/TiO2 nanocomposites prepared by dip‐coating method

In this study, we investigated the influence of TiO₂ content and thickness of polystyrene (PS) template on film‐formation behavior of PS/TiO₂ composites using fluorescence and ultraviolet–visible techniques in conjunction with scanning electron microscopy. Films were prepared by coating PS templates with various layers of TiO₂ using dip‐coating method. The results showed that PS latexes present complete film formation on top surface of composites. After extraction of PS, a well‐defined interconnected porosity were obtained for thin films when TiO₂ content was increased, whereas thick samples did not present any interconnected porous structures above a certain TiO₂ layer. POLYM. ENG. SCI., 54:288–302, 2014. © 2013 Society of Plastics Engineers     

Photoactivity of Poly(lactic acid) nanocomposites modulated by TiO2 nanofillers

Photoactivity of poly(lactic acid) (PLA) nanocomposites is of great interest for rational design of products for either short‐term/single‐use or long‐term/durable applications. We prepared PLA/TiO₂ nanocomposite films through a solution mixing/film casting method. Results showed that photodegradability/photostability of PLA could be well modulated by selecting appropriate TiO₂ nanofillers. TiO₂ nanoparticles and nanowires were characterized using X‐ray diffraction, UV–Vis–NIR spectrophotometer, and scanning electron microscopy. Changes in color, weight, structure, thermal stability, and phase transitions of PLA and nanocomposite films before and after UV irradiation were evaluated to study photoactivity characteristics. Pure PLA exhibited moderate photodegradability, but the photodegradability and photostability of PLA nanocomposites (PNA) were significantly enhanced by NanoActive (NA) TiO₂ nanoparticles and A type TiO₂ nanowires, respectively. Pure PLA had a weight loss of 27% after 38 days of UV irradiation. The weight loss of photodegradable (PD) PNA (PNA = PLA with 1% NA TiO₂) reached 38%, whereas that of photostable (PS) nanocomposites (P3AW) (P3AW = PLA with 3% A type TiO₂ nanowire) was only 5%. PD PLA exhibited characteristic peaks of carboxylic acid OH stretching and C?C double bond after UV irradiation in Fourier‐transform infrared spectra, whereas spectra of PS PLA remained almost the same. Thermal decomposition temperatures, glass transition temperatures, and melting temperatures of PD PLAs decreased dramatically after UV irradiation, but no obvious changes were observed for those of PS PLAs. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40241.     

Preparation and characterization of cerium‐doped titanium dioxide/ultrahigh‐molecular‐weight polyethylene porous composites with excellent photocatalytic activity

Porous ultrahigh‐molecular‐weight polyethylene (UHMWPE)‐based composites filled with surface‐modified Ce‐doped TiO₂ nanoparticles (Ce–TiO₂/UHMWPE) were prepared by template dissolution. The composites were characterized by Fourier transform infrared spectroscopy, ultraviolet (UV)–visible spectroscopy, diffuse reflectance spectra, and scanning electron microscopy); the photocatalytic activity was also evaluated by the decomposition of methyl orange under UV exposure. The results demonstrate that the severe aggregation of Ce–TiO₂ nanoparticles could be reduced by surface modification via a silane coupling agent (KH570). The Ce–TiO₂/UHMWPE porous composites exhibited a uniform pore size. Doping with Ce⁴⁺ effectively extended the spectral response from the UV to the visible region and enhanced the surface hydroxyl groups of the TiO₂ attached to the matrix. With a degradation rate of 85.3%, the 1.5 vol % Ce–TiO₂/UHMWPE sample showed the best photocatalytic activity. The excellent permeability of the porous composites is encouraging for their possible use in wastewater treatment. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation,characterization, and mechanical/tribological properties of polyamide 11/Titanium dioxide nanocomposites

In this study, the effects of the surface chemical modification of titanium dioxide (TiO₂) nanoparticles and their addition into polyamide 11 (PA11) on the mechanical, dynamic‐mechanical, and tribological properties of PA11/TiO₂ nanocomposites were investigated. To improve the interfacial adhesion between the nanoparticles and the polymeric matrix, the surface of TiO₂ nanoparticles was modified with 3‐aminopropyl trimethoxysilane (ATPMS). Nuclear magnetic resonance (NMR), infrared spectroscopy (IR), and thermogravimetric analysis (TG) were used to evaluate the efficiency of the surface chemical modification of TiO₂ nanoxide. PA11/TiO₂ nanocomposites with 2 and 4 wt% of TiO₂ were prepared in an internal mixer. The interfacial adhesion between the matrix and the TiO₂ was evaluated by dynamic‐mechanical analysis (DMA), and the dispersion of nanoparticles was analyzed by scanning electron microscopy (SEM). The NMR spectrum of the modified TiO₂ exhibited peaks in the region between −55 ppm and −70 ppm, indicating disubstituted and trisubstituted chemical structures between alkoxysilano structures and TiO₂. Nanocomposites with modified TiO₂ exhibited the lowest tan δ peak values, which provide evidence that the chemical modification of the TiO₂ facilitated energy dissipation at the interface of TiO₂ with the PA11 matrix. Surface modification of the TiO₂ nanoparticles with ATPMS caused a greater reduction of the mass loss by abrasion when compared with nonmodified PA11/TiO₂ nanocomposites; this reduction reached approximately 70% in comparison with the mass loss of neat PA11. POLYM. COMPOS., 37:1415–1424, 2016. © 2014 Society of Plastics Engineers     

Thermal and thermo‐oxidative stability of thermoplastic polymer nanocomposites with arylated [60]fullerene derivatives

Nanocomposite films of polystyrene (PS) and poly(methyl methacrylate) (PMMA) were prepared by loading four variations of fullerenes such as pristine C₆₀, multiarylated [60]fullerenes with tolyl (tolyl‐C₆₀) and phenol groups (phenol‐C₆₀), and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM). The TGA analysis showed no appreciable change in their thermal and thermo‐oxidative stabilities for PS/tolyl‐C₆₀ and PS/phenol‐C₆₀ films, but significant improvement up to +45°C for PS/C₆₀ and PS/PCBM films even under air. The thermo‐oxidative stability of PMMA/phenol‐C₆₀ and PMMA/PCBM, however, exhibited slightly larger improvements over that of PMMA/C₆₀. We believe that the radical‐scavenging ability of π‐conjugative fullerenes and the dispersibility of fullerene–polymer combinations play key roles in these enhancements. We also found that optimal loading occurred at a relatively low content of fullerenes (0.4–0.8 wt%) probably because larger amounts may interfere with the morphological interaction of polymer chains which is essential for the thermal persistency of polymer. POLYM. COMPOS. 37:1143–1151, 2016. © 2014 Society of Plastics Engineers     

Synthesis of iron oxides intercalated montmorillonite and α‐zirconium phosphate particles and their applications in polystyrene composites

Three kinds of particles of organically modified montmorillonite (OMT) intercalated with iron oxides (Fe‐OMT), hexadecyltrimethylammonium bromide (CTAB) and ethylamine (EA)‐modified zirconium phosphate (ZrP) intercalated with iron oxides, named as Fe‐ZrP(CTAB) and Fe‐ZrP(EA), respectively, were synthesized through a simple route. Characterization of these particles showed that they had a mesoporous lamellar structure with high specific surface area and mesoporous volume. The influence of these particles on the thermal properties and combustion effluents of polystyrene (PS) were comparatively studied with the widely used OMT. The results suggested that the presence of Fe‐OMT, Fe‐ZrP(CTAB), and Fe‐ZrP(EA) imparted PS with an increased thermal degradation onset temperature and a higher glass transition temperature, but they could not increase the thermo‐oxidative stability remarkably as OMT did. Meanwhile, Fe‐ZrP(CTAB) and Fe‐ZrP(EA) exhibited stronger acidity and higher efficiency in preventing the condensed phase oxidation than either OMT or Fe‐OMT, since they imparted the PS composites with a higher ratio of CO/CO₂ in the combustion effluents. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42737.     

Employment of ultrasonic waves for the preparation of PVA/TiO2‐BSA nanocomposites: Mechanical,thermal, and optical properties

The goal of this project is to obtain poly(vinyl alcohol) (PVA)/TiO₂‐bovine serum albumin (BSA) nanocomposite (NC) films in different weight percentages of modified TiO₂. For this purpose, to prevent the accumulation of nanoparticles (NPs) in the PVA matrix, the surface of the TiO₂ NPs was treated with the BSA molecules. To achieve this aim, ultrasonic waves were used as an environmentally friendly and green process that decrease the time of reactions, help better spreading of TiO₂ NPs and maintain dimensions of TiO₂ NPs in the nanoscale range. In the end, the features of the PVA/TiO₂‐BSA NC films were considered with a variety of techniques. The Fourier transform infrared spectroscopy, energy dispersive X‐ray, and X‐ray diffraction showed that the BSA was well placed on the surface of TiO₂ NPs. The thermal gravimetric analysis and UV‐visible results demonstrated that all the PVA/TiO₂‐BSA NC films have better thermal and optical properties than the pure PVA. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46558.     

Morphological and thermal properties of photodegradable biocomposite films

Biocomposites containing ultraviolet (UV) radiation absorbing inorganic nanofillers are of great interest in food packaging applications. The biodegradable polylactide (PLA) composite films were prepared by solvent casting method by incorporating 1 wt % of titanium dioxide (TiO₂) and Ag‐TiO₂ (silver nanoparticles decorated TiO₂) nanoparticles to impart the photodegradable properties. The films were exposed to UV radiation for different time periods and morphology of the composite films before and after UV exposure were investigated. The results showed that homogenous filler distribution was achieved in the case of Ag‐TiO₂ nanoparticles. The thermal properties and thermomechanical stability of the composite film containing Ag‐TiO₂ nanoparticles were found to be much higher than those of neat PLA and PLA/TiO₂ composite films. The scanning electron microscopy and X‐ray diffraction studies revealed that the photodegradability of PLA matrix was significantly improved in the presence of Ag‐TiO₂ nanoparticles. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation of photodegradable polypropylene/clay composites based on nanoscaled TiO2 immobilized organoclay

Photodegradable polypropylene (PP) composites were prepared via melting blending using PP and titanium dioxide (TiO₂) immobilized organically modified montmorillonite (organoclay). TiO₂ immobilized organoclay (TiO₂‐OMT) was synthesized by immobilizing anatase TiO₂ nanoparticles on organically modified clay via sol–gel method. The structure and morphology of TiO₂‐OMT were characterized by XRD and scanning electron microscope (SEM), which showed that anatase TiO₂ nanoparticles with the size range of 8–12 nm were uniformly immobilized on the surface of organoclay layers. Diffuse reflection UV–vis spectra revealed TiO₂‐OMT had similar absorbance characters to that of commercial photocatalyst, Degussa P25. The solid‐phase photocatalytic degradation of PP/TiO₂‐OMT composites was investigated by FTIR, DSC, GPC and SEM. The results indicated that TiO₂‐OMT enhanced the photodegradation rate of PP under UV irradiation. This was due to that immobilization of TiO₂ nanoparticles on organoclay effectively avoided the formation of aggregation, and thereby increased the interface between PP and TiO₂ nanoparticles. After 300 h irradiation, the average molecular weight was reduced by two orders of magnitude. This work presented a promising method for preparation of environment‐friendly polymer nanocomposites. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers.     

Morphologies and properties of poly(phthalazinone ether sulfone ketone) matrix ultrafiltration membranes with entrapped TiO2 nanoparticles

Poly(phthalazine ether sulfone ketone) (PPESK) is a newly developed membrane material with superior thermal stability and comprehensive properties. Titanium dioxide (TiO₂)‐entrapped PPESK ultrafiltration (UF) membranes were formed by dispersing uniformly nanosized TiO₂ particles in the casting solutions. Initially, the inorganic nanoparticles were organically modified with silane couple reagent to overcome the aggregation and to improve the dispersibility in organic solvent. The membranes were prepared through the traditional phase inversion method. The effects of inorganic TiO₂ nanoparticles on the membrane surface morphology and cross section structure were investigated using scanning electronic microscopy (SEM) and atomic force microscopy (AFM). Water contact angle (CA) measurement was conducted to investigate the hydrophilicity and surface wettability of the membranes. The influence of TiO₂ on the permeability, antifouling, and tensile mechanical properties of the PPESK membranes were evaluated by UF experiments and tensile tests. The experimental results showed that the obtained TiO₂‐entrapped PPESK UF membranes exhibit remarkable improvement in the antifouling and mechanical properties because of the introduction of TiO₂ nanoparticles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3623–3629, 2007     

Morphology and properties of highly filled iPP/TiO2 nanocomposites

Nanocomposites based on isotactic polypropylene (iPP) and titanium dioxide (TiO₂) nanoparticle containing 1–15 vol% (4.6–45.5 wt%) of the nanoparticle were prepared by the melt blending process. The effect of an anhydride‐modified polypropylene as a compatibilizer on dispersion of TiO₂ nanoparticles was assessed using SEM. TGA and DSC analysis were performed to study the thermal properties of the nanocomposites. Crystalline structures of iPP in the presence of TiO₂ were analyzed by XRD. Mechanical properties of the nanoparticles were measured and a micromechanical analysis was applied to quantify interface interaction between the polymer and particle. SEM results revealed improvement of TiO₂ particle dispersion by adding the compatibilizer. It was shown that the thermal stability and crystalline structure of the nanocomposite are significantly affected by the state of particle dispersion. TiO₂ nanoparticles were shown to be strong β‐nucleating agents for iPP, especially at concentrations less than 5 vol%. Presence of the β‐structure crystals reduced the elastic modulus and yield strength of the nanocomposites. Micromechanical analysis showed enhanced interaction between organic and inorganic phases of the compatibilized nanocomposites. POLYM. ENG. SCI., 54:874–886, 2014. © 2013 Society of Plastics Engineers     

Surface modification of titanium dioxide nanoparticles by polyaniline via an in situ method

BACKGROUND: Nanoparticulate titanium dioxide (TiO₂) has the advantages of high chemical stability, high photocatalytic activity to oxidise pollutants in air and water, relatively low price and non‐toxicity. However, its high surface energy leads to the aggregation of nanoparticles. In addition, the wide band gap of TiO₂ (3.2 eV) only allows it to absorb ultraviolet (UV) light (<387 nm), which represents just a small fraction (3–5%) of the solar photons. These factors have limited its use in many fields. In this study, nanoparticulate TiO₂ was modified by polyaniline (PANI) in order to enhance its photoactivity under UV light and sunlight illumination. RESULTS: TiO₂ nanoparticles were modified by PANI via a chemical oxidative method. The introduction of small amounts of PANI enhanced the dispersion of TiO₂ nanoparticles and improved the photocatalytic activity under UV light. In addition, the band gap energies of all PANI/TiO₂ nanocomposites were lower than that of neat TiO₂ nanoparticles, so the PANI/TiO₂ nanocomposites can be excited to produce more electron–hole pairs under sunlight, which could result in higher photocatalytic activities. CONCLUSION: The modification of nanoparticulate TiO₂ by PANI can increase its photoactivity in the process of phenol degradation under UV light and sunlight illumination. Copyright © 2008 Society of Chemical Industry     

Thermal properties of PMMA/TiO2 nanocomposites prepared by in-situ bulk polymerization

The surface of anatase TiO₂ nanoparticles, obtained by the controlled hydrolysis of titanium tetrachloride, was modified by 6-palmitate ascorbic acid. The surface modified TiO₂ nanoparticles were dispersed in methyl methacrylate and mixed with a appropriate amount of poly(methyl methacrylate) to obtain a syrup. The nanocomposite sheets were made by bulk polymerization of the syrup in a glass sandwich cell using 2,2′-azobisisobutyronitrile as initiator. The molar masses and molar mass distributions of synthesized poly(methyl methacrylate) samples were determined by gel permeation chromatography. The content of unreacted double bonds in synthesized samples was determined by ¹H NMR spectroscopy. The influence of TiO₂ nanoparticles on the thermal stability of the poly(methyl methacrylate) matrix was investigated using thermogravimetric analysis and differential scanning calorimetry. The synthesized samples of poly(methyl methacrylate) have different molar mass and polydispersity depending on the content of the surface modified TiO₂ nanoparticles. The values of glass transition temperature of so prepared nanocomposite samples were lower than for pure poly(methyl methacrylate), while the glass transition temperature of samples preheated in inert atmosphere was very similar to the glass transition temperature of pure poly(methyl methacrylate). The thermal stability of nanocomposite samples in nitrogen and air was different from thermal stability of pure poly(methyl methacrylate). POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers