The TiO2–Clay-LDPE Nanocomposite Packaging Films: Investigation on the Structure and Physicomechanical Properties

The role of nanoclays and TiO₂ nanoparticle loadings were investigated on low density polyethylene crystalline structure, in addition to studying packaging film properties such as barrier, thermal and mechanical properties. The polymer crystal study indicated for the orthorhombic crystal phase and about 20% lower degree of crystallinity for nanocomposites containing more than 2 wt.% TiO₂ nanoparticles. Based on the X-ray diffraction technique, the dispersion of nanoclays was improved to almost good degree of clay exfoliation with the company of 4 wt.% TiO₂ nanoparticles. In agreement with XRD results, the TEM morphological studies mainly suggest that TiO₂ has a helpful effect on nanoclay exfoliation. The increase in degradation temperature of nanocomposites may be attributed to the formation of inorganic char on polymer melt. The barrier properties of TiO₂/clay nanocomposite packaging films depend mainly on nanoclay loading with an unclear trend from TiO₂ nanoparticles. The increase in elastic modulus and the yield stress of nanocomposite films showed great effects on film mechanical properties by nanoclays.     

Synthesis of clay–TiO2 nanocomposite thin films with barrier and photocatalytic properties for food packaging application

In this study, low‐density polyethylene (LDPE) nanocomposite films with two types of nanoparticles, TiO₂ (3 wt %) and Closite 20A (3 and 5 wt %), were prepared using a melt blow extrusion as an industrial method and their properties such as mechanical properties, water vapor, oxygen and carbon dioxide gas barrier, and antimicrobial activity were tested. Transmission electron microscopy (TEM) and X‐ray diffraction (XRD) were also performed to determine the degree of dispersion and exfoliation of nanoparticles. Mechanical test indicated that the reinforcement in the presence of the nanocomposites was more than that with their conventional counterparts, and the highest stiffness was achieved in a sample containing 5 wt % clay and 3 wt % TiO₂. Exfoliation of silicate layers and a good dispersion of TiO₂ nanoparticles in LDPE were achieved as confirmed by XRD and TEM. The gas barrier properties were improved after formation of the nanocomposites especially by insertion of 5 wt % of clay nanoparticles as a filler in the LDPE matrix. The photocatalytic effect of the nanocomposite film was carried out by antimicrobial evaluation against Pseudomonas spp. and Rhodotorula mucilaginosa and by ethylene removal test using 8 W ultraviolet (UV) lamps with a constant relative intensity of 1 mW cm^?2. The greatest effects were recorded by combining UVA illumination and active film. It was also proven that the photocatalyst thin film with improved barrier properties prepared by extrusion could be used in horticultural product packaging applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41764.     

Effect of Tio2 Nanoparticles on the Antibacterial and Physical Properties of Low-Density Polyethylene Film

In this study, TiO₂ nanoparticles were incorporated into low-density polyethylene by melt blending. Morphological properties and dispersion behavior of TiO₂ nanocomposite were characterized through field emission scanning electron microscope, X-ray diffraction, and Fourier transform infrared spectroscopy. Thermal stability of the nanocomposites was determined by thermogravimetric analysis. Moreover, the mechanical properties of nanocomposites were determined. Antimicrobial activity of TiO₂ nanocomposites was investigated by in vitro test. Dispersion of the nanoparticles was good in nanocomposites_. According to thermogravimetric analysis, incorporation of TiO₂ nanoparticles into low-density polyethylene enhanced the thermal stability. Mechanical properties of nanocomposites were improved by TiO₂ nanoparticles. Results showed that the antibacterial effect of low-density polyethylene –TiO₂ nanocomposite was significantly enhanced by TiO₂nanoparticles (p?2 nanoparticles not only can improve the properties of low-density polyethylene but they also have the potential to be used as an active food packaging film.     

Transparent low‐density polyethylene/starch nanocomposite films

Low‐density polyethylene (LDPE)/starch nanocomposite films were prepared by melt extrusion process. The first step includes the preparation of starch–clay nanocomposite by solution intercalation method. The resultant product was then melt mixed with the main matrix, which is LDPE. Maleic anhydride‐grafted polyethylene (MAgPE), produced by reactive extrusion, was used as a compatibilizer between starch and LDPE phases. The effects of using compatibilizer, clay, and plasticizers on physico‐mechanical properties were investigated. The results indicated that the initial intercalation reaction of clay layers with starch molecules, the conversion of starch into thermoplastic starch (TPS) by plasticizers, and using MAgPE as a compatibilizer provided uniform distribution of both starch particles and clay layers, without any need of alkyl ammonium treatment, in LDPE matrix. The nanocomposite films exhibited better tensile properties compared to clay‐free ones. In addition, the transparency of LDPE film did not significantly change in the presence of TPS and clay particles. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Aging Studies on Food Packaging Films Containing β-Cyclodextrin-Grafted TiO2 Nanoparticles

Polymeric materials, such as polyvinyl alcohol (PVA) and ethylene–PVA copolymers (EVOH) are widely used in the food sector as packaging materials because of their excellent properties. TiO₂ nanoparticles (NPs) show photocatalytic activity; when added to the aforementioned polymers, on the one hand, they are expected to provide bactericidal capacity, whereas on the other hand, they could favor nanocomposite degradation. These types of nanoparticles can be derivatized with cyclodextrin macromolecules (CDs), which can act as food preservative carriers, increasing the packaging food protective properties. In this work, films containing β-Cyclodextrin (βCD)-grafted TiO₂ nanoparticles and PVA or EVOH were prepared. Regarding the photocatalytic activity of the nanoparticles and the possible environmental protection, accelerated aging tests for PVA, EVOH, and their composites with cyclodextrin-grafted TiO₂ nanoparticle (NP) films were performed by two methods, namely, stability chamber experiments at different conditions of temperature and relative humidity and UV light irradiation at different intensities. After analyzing the systems color changes (CIELAB) and Fourier transform infrared spectroscopy (FTIR) spectra, it was observed that the film degradation became more evident when increasing the temperature (25–80 °C) and relative humidity percentage (28–80%). There was no significant influence of the presence of CDs during the degradation process. When irradiating the films with UV light, the largest color variation was observed in the nanocomposite films, as expected. Moreover, the color change was more relevant with increasing NP percentages (1–5%) due to the high photocatalytic activity of TiO₂. In addition, films were characterized by FTIR spectroscopy and variation in the signal intensities was observed, suggesting the increase of the material degradation in the presence of TiO₂ NPs.     

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     

Thermal annealing induced cave in and formation of nanoscale pits in Ag–TiO2 plasmonic nanocomposite thin film

Ag–TiO₂ nanocomposite thin films on silica glass were prepared through thermal evaporation in combination with RF magnetron sputtering. Thermal annealing induced changes in the optical, morphological and structural properties of Ag–TiO₂ nanocomposites were examined using optical absorption, photoluminescence spectroscopy, Raman spectroscopy, FESEM, AFM and XRD. FESEM and AFM studies revealed cave in of the Ag–TiO₂ thin film at various places leading to the formation nanoscale pits upon thermal annealing at 600 °C. The computed average size of pits was found to be 54 nm. Raman studies indicated 600 °C annealing induced transformation of anatase phase of TiO₂ into anatase/rutile mixed phase TiO₂. Optical absorption spectra showed systematic changes due to the effects of mixed phase formation and variation in the plasmonic behavior upon annealing. PL results of the as deposited Ag–TiO₂ thin film showed peaks at 377, 402, 432 and 486 nm. PL studies of Ag–TiO₂ nanocomposites treated at different annealing temperatures revealed changes in defect concentration in TiO₂. The tentative mechanism for the creation of nanoscale pits in Ag–TiO₂ thin film through thermal annealing was proposed.     

Polyethylene terephthalate/low density polyethylene/titanium dioxide blend nanocomposites: Morphology,crystallinity, rheology,and transport properties

Physical features of polyethylene terephthalate (PET)/low density polyethylene (LDPE) immiscible blends, rich in PET, with and without titanium dioxide (TiO₂) nanoparticles are studied. These materials are of industrial interest, because they can be obtained by recycling PET bottles containing TiO₂ with their corresponding polyethylene made caps. Their potential application in packaging is investigated. Droplet-matrix morphology is observed by scanning electron microscopy; coalescence occurs during compression molding. Transmission electron microscopy results show that TiO₂ nanoparticles are located at the interface between PET and LDPE, forming a physical barrier that favors development of smaller droplets. Thermal analysis results are compatible with the morphology of the blends and the location of the TiO₂ nanoparticles. Viscosity obtained by extrusion continuous flow and oscillatory flow measurements in the linear regime show that some of the blends have viscoplastic behavior. Permeability results reveal that 80PET/20LDPE/TiO₂ blend nanocomposite shows a balanced barrier character to both oxygen and water vapor. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46986.     

Enhanced photoresponse and photocatalytic activities of graphene quantum dots sensitized Ag/TiO2 thin film

TiO₂ thin films were fabricated through hydrothermal method. Silver nanoparticles were loaded on TiO₂ thin films via photoreduction technique. Subsequently, the graphene quantum dots (GQDs) were spin‐coated on the Ag/TiO₂ nanocomposites thin films. The crystal structure, surface morphology and UV‐vis absorbance were tested by XRD, SEM and ultraviolet‐visible spectrophotometer. These results indicated that Ag nanoparticles and GQDs are anchored on the TiO₂ nanorods. Absorbance of Ag/TiO₂ and GQDs/Ag/TiO₂ nanocomposite thin films have been extended into the visible region. Visible‐light response of the samples were investigated by electrochemical workstation. The photoresponse of the sample can be enhanced by sensitization of the Ag nanoparticles and GQDs. The enhanced visible‐light response may be due to the surface plasmon resonance of silver nanoparticles and visible absorbance of GQDs. The highest photocatalytic activity has been observed in the 9‐GQDs/Ag/TiO₂ composite thin film. The efficient charge separation and transportation can be achieved by introducing the Ag nanoparticles and GQDs in the TiO₂ thin film.     

Effect of TiO2 nanoparticles on the antibacterial and physical properties of polyethylene-based film

TiO₂ nanoparticles and their application in packaging systems have attracted a lot of attention because of its antimicrobial activity. In this work, effect of TiO₂ nanoparticles on the antibacterial and physical properties of polyethylene (PE)-based film was investigated. Results indicated that the antibacterial activity of TiO₂-incorporated PE films should be due to the killing effect property of TiO₂ nanoparticles against microorganisms. The TiO₂-incorporated PE film exhibited more effective antibacterial activity for Staphylococcus aureus. The antibacterial activity to inactivate Escherichia coli or S. aureus was improved by UV irradiation. The inhibition ratio of TiO₂-incorporated PE films sample irradiated for 60 min by UV light was improved significantly, which were 89.3% for E. coli and 95.2% for S. aureus, respectively, compared to that of TiO₂-PE film without UV irradiation. The analysis of physical properties revealed that TiO₂ nanoparticles increased the tensile strength and elongation at break of PE-based film. The climate resistance of nano-TiO₂ films is greatly enhanced, compared to that of the blank PE film. Water vapor transmission increased from 18.1 to 24.6 g/m²·24 h with the incorporation of TiO₂ nanoparticles. Results revealed that PE based film incorporating with TiO₂ nanoparticles have a good potential to be used as active food packaging system.     

LDPE/Bi2O3 nanocomposites: Enhanced mechanical,dielectric, and optical properties

This study is focused on investigating the role of bismuth oxide (Bi₂O₃) nanoparticles to improve structural, optical, electrical, and mechanical properties of low-density polyethylene (LDPE). For this purpose, Bi₂O₃ nanoparticles were synthesized by using the solvothermal method and examined by transmission electron microscopes (TEM), x-ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy, and ultraviolet–visible (UV–Vis) light absorption methods. LDPE-based nanocomposites were prepared by changing the nanoparticle additive ratio in the composite from 0% to 2% by weight. The composites were analyzed in the context of their FTIR spectra, atomic force microscope (AFM) images, UV–Vis light absorption spectra, stress–strain curves, and energy storage abilities. While the AFM findings indicate a smoother surface for the composites, the optical band gap analysis reveals a slightly decreased direct optical band gap energy. The analyses based on dielectric spectroscopy also highlight the LDPE/0.5% n-Bi₂O₃ composite in terms of the best energy storage capability. Additionally, the highest Young's modulus, toughness, stress at break, and percentage of strain at break were also recorded for the LDPE/0.5% n-Bi₂O₃ composite. In this context, the LDPE/0.5% n-Bi₂O₃ composite with improved dielectric and mechanical properties can be suggested as a new promising LDPE-based nanocomposite with better properties for industrial purposes.     

In situ fibre‐reinforced composite films of poly(lactic acid)/low‐density polyethylene blends: effects of composition on morphology,transport and mechanical properties

This study aimed to investigate the effects of blend composition on packaging‐related properties of poly(lactic acid) (PLA) and low density polyethylene (LDPE) blown films. Blend films with PLA contents of 5–20 wt% were produced and compared. Scanning electron micrographs of cross‐sectional cryofractured surfaces of the blend films revealed that in situ fibre‐reinforced composites were obtained. Viscosity ratio of the polymer components of ca 1 confirmed that fibre formation was favourable for this blend system. PLA microdomains were dispersed throughout the film in forms of long fibres (length‐to‐diameter ratio > 100) and ribbons. The number of fibres and ribbons increased with an increase of PLA content. Critical content of PLA was found to be 20 wt% for effective improvement of both moduli and gas barrier properties. Incorporation of poly[ethylene‐co‐(methyl acrylate)] compatibilizer showed minimal effect on PLA structure. However, it did improve moduli and O₂ barrier properties when sufficient amount (1.5 pph) was used in 10 wt% PLA/LDPE. In short, flow behaviour, ratio of polymer components and degree of compatibility together played intricate roles in the morphology and hence mechanical and transport properties of PLA/LDPE immiscible blends. © 2017 Society of Chemical Industry     

Two-Functional Direct Current Sputtered Silver-Containing Titanium Dioxide Thin Films

The article reports on structure, mechanical, optical, photocatalytic and biocidal properties of Ti–Ag–O films. The Ti–Ag–O films were reactively sputter-deposited from a composed Ti/Ag target at different partial pressures of oxygen on unheated glass substrate held on floating potential U _fl. It was found that addition of ~2 at.% of Ag into TiO₂ film has no negative influence on UV-induced hydrophilicity of TiO₂ film. Thick (~1,500 nm) TiO₂/Ag films containing (200) anatase phase exhibit the best hydrophilicity with water droplet contact angle (WDCA) lower than 10° after UV irradiation for 20 min. Thick (~1,500 nm) TiO₂/Ag films exhibited a better UV-induced hydrophilicity compared to that of thinner (~700 nm) TiO2/Ag films. Further it was found that hydrophilic TiO₂/Ag films exhibit a strong biocidal effect under both the visible light and the UV irradiation with 100% killing efficiency of Escherichia coli ATCC 10536 after UV irradiation for 20 min. Reported results show that single layer of TiO₂ with Ag distributed in its whole volume exhibits, after UV irradiation, simultaneously two functions: (1) excellent hydrophilicity with WDCA < 10° and (2) strong power to kill E. coli even under visible light due to direct toxicity of Ag.     

Conductive and transparent multilayer films for low-temperature TiO2/Ag/SiO2 electrodes by E-beam evaporation with IAD

Conductive and transparent multilayer thin films consisting of three alternating layers (TiO₂/Ag/SiO₂, TAS) have been fabricated for applications as transparent conducting oxides. Metal oxide and metal layers were prepared by electron-beam evaporation with ion-assisted deposition, and the optical and electrical properties of the resulting films as well as their energy bounding characteristics and microstructures were carefully investigated. The optical properties of the obtained TAS material were compared with those of well-known transparent metal oxide glasses such as ZnO/Ag/ZnO, TiO₂/Ag/TiO₂, ZnO/Cu/ZnO, and ZnO/Al/ZnO. The weathering resistance of the TAS film was improved by using a protective SiO₂ film as the uppermost layer. The transmittance spectra and sheet resistance of the material were carefully measured and analyzed as a function of the layer thickness. By properly adjusting the thickness of the metal and dielectric films, a low sheet resistance of 6.5 ohm/sq and a high average transmittance of over 89% in the 400 to 700 nm wavelength regions were achieved. We found that the Ag layer played a significant role in determining the optical and electrical properties of this film.     

Enhanced Solid‐Phase Photocatalytic Degradation Activity of a Poly(vinyl chloride)‐TiO2 Nanocomposite Film with Bismuth Oxyiodide

A new type of photodegradable poly(vinyl chloride)‐bismuth oxyiodide/TiO₂ (PVC‐BiOI/TiO₂) nanocomposite film was prepared by embedding a nano‐TiO₂ photocatalyst modified by BiOI into the commercial PVC plastic. The solid‐phase photocatalytic degradation behavior of the as‐prepared film was investigated in ambient air at room temperature under UV light irradiation, with the aid of UV‐Vis spectroscopy, weight loss monitoring, scanning electron microscopy, and FT‐IR spectroscopy. Compared to the PVC‐TiO₂ nanocomposite film, the PVC‐BiOI nanocomposite film and the pure PVC film, the PVC‐BiOI/TiO₂ nanocomposite film exhibited a higher photocatalytic degradation activity. The optimal mass ratio of BiOI to TiO₂ was found to be 0.75 %. The weight loss rate of the PVC‐BiOI/TiO₂ nanocomposite film reached 30.8 % after 336 h of irradiation, which is 1.5 times higher than that of the PVC‐TiO₂ nanocomposite film under identical conditions. The solid‐phase photocatalytic degradation mechanism of the nanocomposite films was briefly discussed.     

Structure and functional properties of glycerol-plasticized starch/TiO<Subscript>2</Subscript> nanocomposite materials obtained through resonant wave mixing

Resonant wave mixing is a promising technology based on employing non-linear waves to intensify heat and mass transfer and enhancing dispersion processes in mixed materials. In the present work, for the first time, resonant wave mixing was used to prepare film-forming dispersions based on gelatinized maize starch and spherical TiO₂ nanoparticles (0.5–1.5 wt%) synthesized by sol–gel technique. Then, nanocomposite films were obtained by solution casting method. The dynamic viscoelastic properties, including relaxation spectra of the film-forming dispersions were investigated by oscillatory squeeze film rheometry, while the structure of the nanocomposite films was studied by X-ray diffraction, FTIR spectroscopy and scanning electron microscopy. The mechanical, water-related and UV-protective properties of the film materials were evaluated. It was shown that nanofiller incorporation enhanced the density of the 3D network structure of a gelatinized starch dispersion. The resonant wave treatment favored homogenous dispersion of the TiO₂ nanoparticles in the nanocomposites. All nanocomposite film samples displayed higher tensile strength and lower water vapor permeability in comparison with starch films without the nanofiller. The obtained nanocomposites possessed UV-protective properties, which could be potentially applied to produce biodegradable packaging materials with improved functional characteristics.     

Design and performance evaluation of multilayer packaging films for blister packaging applications

Five multilayer packaging film structures consisting of amorphous poly(ethylene terephthalate) (APET), low‐density polyethylene (LDPE), polypropylene (PP), and acrylonitrile/methyl acrylate copolymer (Barex) films [i.e., APET/polyethylene (PE), APET/PP, APET/PE + UV inhibitor, APET/PP/PE, and APET/Barex/PP] for blister packaging applications were designed and produced. Blister containers with APET/PE and APET/Barex/PP structures were prepared, and their optical, mechanical, barrier (O₂, CO₂, and H₂O), physical, and product/package compatibility performance properties were evaluated. Package/product compatibility with simulants (soy sauce and sunscreen skin cream) at 37.8°C was evaluated for 3, 7, 14, and 28 days in the multilayer films and the blister containers. APET/Barex/PP film showed significantly better O₂ and CO₂ barrier performance than the other four film structures. The UV inhibitor had no significant effect on the barrier properties in the APET/PE film structure. All of the film structures showed high enough elastic storage modulus values to be applied to blister packaging in a broad range of temperatures between ?45 and 80°C. The glass‐transition temperature of APET, which was responsible for the elastic modulus of the multilayer structure, decreased after the samples were exposed to the skin cream. This decrease may have been due to the sorption of the skin cream's active ingredients, such as ethylhexyl methoxycinnamate. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Mechanical recycling of nanocellulose containing multilayer packaging films

The aim of this study was to demonstrate mechanical recycling of low density polyethylene (LDPE) films coated with a thin layer of cellulose nanofibrils (CNFs). CNF acts as an effective barrier against oxygen and mineral oil residues. Two different CNF grades were tested, and both were applied onto plasma activated LDPE film using a pilot coating line. The coated films were shredded with the help of liquid nitrogen, compacted and compounded with virgin LDPE and compatibilizer, and processed into cast films and injection molded test specimens. The CNF coatings were completely blent as microscale agglomerates in the LDPE matrix. The effect of these agglomerates on the barrier and heat sealing properties was statistically insignificant compared to recycled uncoated LDPE. The mechanical properties were only moderately changed. CNF‐coated LDPE films can therefore be recycled back into films without sacrificing the characteristic properties of the base polymer. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46237.     

Effect of hydrophilic and hydrophobic cyclodextrins on the release of encapsulated allyl isothiocyanate (AITC) and their potential application for plastic film extrusion

Allyl isothiocyanate (AITC), a natural pungent flavor from wasabi and horseradish, is well-known antimicrobial agents against foodborne pathogens. However, its highly volatile nature and low thermal stability restrict its application in the food packaging industry. Also, its strong organoleptic characteristics hinder its application at a higher dosage. We encapsulated AITC in β-cyclodextrin (β-CD) and triacetyl-β-CD (TA-β-CD) and evaluated the performance as slow releasing active compounds through low-density polyethylene (LDPE)–cyclodextrins (CDs) matrix. Also, the thermal, optical, mechanical, and barrier properties of two ternary blends, LDPE/β-CD/AITC(L-CDs) and LDPE/TA-β-CD/AITC(L-TACDs), were investigated to compare their compatibility under the plastic extrusion process. During the 15 days of the storage period, L-TACDs maintained more consistent AITC release and a higher concentration than L-CDs. Also, the blending of LDPE and TA-β-CD was more compatible with that of LDPE and β-CD. No significant optical, mechanical, and barrier property changes were observed in LDPE with less than 3% of TA-β-CD while L-CDs showed substantial agglomeration on the ternary blend films and the lower mechanical and barrier properties than pure LDPE. The results indicate that the LDPE films containing TA-β-CD/AITC can be applied as an effective antimicrobial packaging material for food and nonfood applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48137.     

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