CaCO3 as a new member of high solar-reflective filler on the cooling property in polymer composites

Calcium carbonate (CaCO₃) is the most commonly used inorganic filler in polymer materials to improve the mechanical properties and reduce the costs. However, there are few reports on the preparation of cooling materials using CaCO₃. In this study, CaCO₃ was introduced into the polymer matrix as a solar reflective filler to prepare passive cooling materials. Specifically, the influences of CaCO₃ content on the structure and performances of polyvinyl chloride (PVC)/CaCO₃ composite films were characterized by scanning electron microscope (SEM), contact angle test, surface roughness and glossiness, solar reflectivity, thermal emissivity, temperature test and mechanical property characterization. When the volume fraction of CaCO₃ reaches 67%, the total solar reflectance of PVC/CaCO₃ composite films is 80.8%, which is 351.4% higher than that of PVC films. CaCO₃ powder has little influence on the thermal emissivity of the atmospheric window (3-5 μm and 8-13 μm) of the composite films, which remains at a high level about 0.86. In temperature test, the final temperature of sample 67 v% is only 26.8°C, which is only 2.8°C higher than the room temperature and 22.2°C lower than that of PVC films. For comparison, the cooling performance of PVC/titanium dioxide (TiO₂) composite films with 10 v% TiO₂ was also measured, and the final temperature is 29.1°C, even 2.3°C higher than that of PVC/CaCO₃ composite films with 67 v% CaCO₃. In this study, the cost-effective and solar-reflective PVC/CaCO₃ composites have potential application in cooling material field.     

SrTiO3 as a new solar reflective pigment on the cooling property of PMMA-ceramic composites

Polymer-ceramic hybridization is an important method for preparing functional materials. Strontium titanate (SrTiO₃, ST), a typical perovskite ceramic, has been widely applied in the electronics industry and photocatalytic fields. However, ST was barely reported to be utilized in cool materials. Herein, ST ceramic, as a solar reflective pigment, was introduced into a polymer matrix to prepare cool material. Specifically, the influences of both weight contents and surface grafting modification about ST on the properties of poly(methyl methacrylate) (PMMA)/ST composites were investigated, which include cooling performance, surface roughness, thermal emissivity, dispersion of particles and mechanical strength. The obtained composites containing 20 wt% unmodified ST possess excellent cooling property due to high thermal emissivity (86.8%, in 8–13 μm) and high solar reflectance (70.7%, in the whole solar band) which increased by 142% than that of pure PMMA resin. Temperature test highlighted that the composites containing 20 wt% unmodified ST was only 26.6 °C, 11.4 °C lower than that of PMMA resin and only 2 °C higher than initial temperature. Moreover, the surface grafting modification of ST by the silane coupling agent was proved to improve the dispersibility of ST in PMMA resin. Both the cooling and mechanical properties of composites containing modified ST particles were further improved. Though the solar reflectance of PMMA/ST composites was lower than that of PMMA/TiO₂ composites, temperature tests showed that the PMMA/ST composites had a similar cooling performance with the PMMA/TiO₂ composites when the content of the ceramic particles were 5.8 v%. This work not only prepared the polymer-ceramic hybrid materials with excellent cooling performance but also expanded the application of ST ceramic in the field of composites.     

Mesoporous TiO<Subscript>2</Subscript> microspheres synthesized via a facile hydrothermal method for dye sensitized solar cell applications

Mesoporous TiO₂ microspheres were successfully synthesized by a facile hydrothermal process and the obtained product was sintered at 450 °C. The sintered TiO₂ powder was characterised by powder X-ray diffraction pattern and the result shows pure anatase phase with good crystalline nature. The morphological image of field emission scanning electron microscopy and high resolution transmission electron microscopy shows spherical shape and size of the particles is around 100 to 300 nm. The Brunauer–Emmett–Teller surface area of synthesized TiO₂ material was 56.32 m² g^?1 and average pore width of synthesized materials was 7.1 and 9.3 nm. Bimodal pore structure of TiO₂ microspheres has been very effective for electrolyte diffusion into photoanode in dye sensitized solar cells. The synthesized anatase TiO₂ microsphere based dye sensitized solar cells have high surface area with light scattering effect to enhance the photocurrent and conversion efficiency than the commercial P25 photoanode material. The power conversion efficiency of synthesized mesoporous TiO₂ microspheres and commercial P25 material is 4.2 and 2.7 % respectively. Therefore bimodal mesoporous anatase TiO₂ microsphere appears to be a promising and potential candidate for dye sensitized solar cells (DSSC) application.     

Low-temperature fabrication of TiO<Subscript>2</Subscript> film on flexible substrate by atmospheric roll-to-roll CVD

Titanium dioxide (TiO₂) thin film was fabricated using titanium isopropoxide as a precursor through an atmospheric low-temperature roll-to-roll chemical vapor deposition method. TiO₂ was deposited on the PET substrate in the temperature range of room temperature to 100°C, and the working pressure was 740 Torr. The surface morphology of TiO₂ thin film was analyzed by field emission scanning electron microscopy and a 2D surface profiler. The results revealed that the growth rate of TiO₂ film was 31 nm/min at 100°C, and it also showed that the surface is uniform and smooth. Moreover, the lowest root mean square roughness (R _q) value of 1.87 nm was obtained for TiO₂ film prepared at 100°C. The composition of TiO₂ film was confirmed by X-ray photoelectron spectroscopy (XPS) analysis. The film showed very good chemical and optical properties while increasing the substrate deposition temperature. The UV–Vis spectroscopy analysis revealed that TiO₂ films exhibited excellent optical transmittance, more than 91% observed in the visible region.     

Highly efficient photocatalytic degradation of methylene blue using carbonaceous WO<Subscript>3</Subscript>/TiO<Subscript>2</Subscript> composites

Recent improvements in the performance of photocatalysts made it possible to tackle pollution through environment friendly methods. This study investigates the modification of the photocatalytic activity of TiO₂ by employing WO₃ and conductive polymers, namely, polyaniline (Pani) and polypyrrole (Ppy). Basing on our previous improvement of TiO₂ using a conductive polymer and activated carbon (AC), this study determines the activated carbon forms of TiO₂. The prepared composites are characterized using X-ray powder diffraction, transmission electron microscopy, Fourier transform infrared, thermogravimetric analysis, Brunauer–Emmet–Teller, and UV–Vis spectroscopy. The specific surface area of the mesoporous composites is as follows: WO₃/TiO₂·AC (Pani) > WO₃/TiO₂·AC (Ppy) > WO₃/TiO₂·Pani > WO₃/TiO₂·Ppy (127 > 98 > 68 > 44 m² g^?1), which exhibited a similar trend to the photocatalytic performances (100 > 95 > 91 > 72 % conversion rate). This result could be attributed to higher porosity, surge of charge separation, and photo-responding range extension induced by the synergistic effect of WO₃, conducting polymers, and TiO₂ in the samples.     

One-pot synthesis of bifunctionalized TiO<Subscript>2</Subscript> mesoporous photocatalyst with visible light response

A series of Fe-doped SH/TiO₂ mesoporous photocatalysts have been firstly prepared by one-pot method using P123 as structure-directing agent. This bifunctionalized mesoporous TiO₂ possesses perfect anatase crystal structure and high surface area. The surface area of Fe-doped SH/TiO₂ mesoporous material is 4 times higher than that of P25. Based on the EPR results, it was found that trivalent Fe ions exist at low spin state and substitutes a part of Ti⁴⁺ ions into TiO₂ lattice. Fe-dropping in TiO₂ extends the adsorption band side of the resulting material to about 600 nm. Much high photocatalytic activity in the degradation of phenanthrene was obtained on the bifunctionalized mesoporous TiO₂ under visible light irradiation (λ > 420 nm), which is 6 times higher than that of pristine mesoporous TiO₂. The enhancement in the photocatalytic activity of bifunctionalized TiO₂ is ascribed to the extended absorption to visible light and strong interaction between SH-groups and PHE molecules.     

Effect of synthesis highly ordered TiO<Subscript>2</Subscript> nanotube arrays with enhanced photocatalytic properties by time,electrolytic voltage,heating temperature and Polyvinyl pyrrolidone

Highly ordered TiO₂ nanotube arrays were prepared by anodization method with doped Polyvinyl pyrrolidone (PVP) addition. The as-prepared samples were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and transmission electron microscopy. The results suggested that TiO₂ nanotubes arrays modified by 0.10 wt% PVP were better uniform and more highly ordered than that of pure TiO₂. The average inner diameter and the tube length of TiO₂ nanotubes were extended approximately 77 nm and 5.21 μm, respectively. Meanwhile, the optimum synthesis conditions (40 V, 4 h and 450 °C) were determined by SEM and XRD. In addition, the photocatalytic activity of the as-prepared samples was investigated for the degradation of RhB under UV-lamp irradiation. The results showed that almost 100 % of RhB was degradation within 80 min by the as-prepared nanotubes in the optimum synthesis conditions. It was indicated that the photocatalytic activity of the as-prepared nanotubes was improved greatly due to their well morphology, enhanced UV-light absorption property and electron transmission ability. In general, this study could provide a principle method to synthesize TiO₂ nanotube arrays with enhanced photocatalytic activity and improved microstructure by anodization process with PVP addition.     

Hydrogen Production from Aqueous Solutions of Glycerol on TiO<Subscript>2</Subscript>/Ru-MCM-41 Photocatalysts Using Solar Light

Ru-MCM-41 molecular sieves were prepared (Si/Ru atomic ratio?=?50 or 100) by a hydrothermal method and impregnated with TiO₂. The materials were characterized by XRD, N₂ physisorption, DRS, SEM and TEM. Their potential application to hydrogen production by photolysis of water using solar light was tested in a batch reactor using mixtures of water and glycerol (0–6.85 mol L^?1) at pH varying from 1 to 11. The photocatalytic efficiency under simultaneous UV (0.05 μW cm^?2) and visible light (90.07 W m^?2) irradiation was compared to the activity of TiO₂/MCM-41 (i.e., no Ru incorporated) and commercial Degussa TiO₂ P25. The most active material was 20%TiO₂/Ru-MCM-41(100) whose performance (220.6 µmol g_Ti ^?1 H₂) was approximately 47 times higher than TiO₂ P25. Characterization results showed the deposition of TiO₂ and revealed the formation of RuO₂ on the surface. Hydrogen generation was improved due to higher charge separation at the TiO₂/RuO₂ heterojunction and to the enhancement of visible light absorption caused by surface plasmon resonance (SPR). Hydrogen production increased with glycerol concentration, tending to stabilize around 40.3 µmol h^?1 g_Ti ^?1 above 4 mol L^?1 of glycerol. Hydrogen generation reached its maximum at extreme values of pH (1 and 11).     

P123 assisted morphology-engineered and hierarchical TiO<Subscript>2</Subscript> microspheres for enhanced photocatalytic activity

In this study, hierarchical titanium dioxide (TiO₂) microspheres with controlled morphology derived from calcination treatment of hierarchical titanate microspheres were fabricated. The obtained hierarchical TiO₂ microspheres with diameters of 1 to 2 µm were composed of polycrystalline anatase nanosheets with thickness of 10 nm. The morphology was manipulated by simply adjusting the molar ratio of tetrabutyl titanate/P123. At a low molar ratio of 17.04, TiO₂ microspheres composed of a large number of nanosheets closely packed together were obtained. At a high molar ratio of 34.08, TiO₂ hybrid architectures with polycrystalline anatase hierarchical microspheres and single-crystal anatase mesoporous (approximately 5 nm) nanospheres were obtained. Investigations on evolution formation revealed that P123 played a key role in the formation of a well-defined hierarchical structure. The photocatalytic performances of the obtained samples were investigated by the degradation of methylene blue and papermaking wastewater. When compared with commercial P25, the obtained hierarchical TiO₂ microspheres exhibit superior photocatalytic activity, high degradation efficiency, and good reproducibility. The product with hybrid architectures exhibited the highest photocatalytic activity. The chemical oxygen demand and the chroma removal rate of papermaking wastewater achieved 85.5 and 100%, respectively, after 12 h of photodegradation.     

Spectral Selective Solar Light Enhanced Photocatalysis: TiO<Subscript>2</Subscript>/TiAlN Bilayer Films

We demonstrate that spectral selective photocatalytic multilayer films can be tailored such that they can harness the full solar spectrum for enhanced photocatalytic gas-phase oxidation of acetaldehyde. Thin films of anatase TiO₂ were deposited on a thin solar absorber TiAlN film to fabricate bilayer TiO₂/TiAlN films by dc magnetron sputtering on aluminium substrates. The structural and optical properties of the films were characterized by X-ray diffraction and Raman spectroscopy. The reaction rate and quantum yield for acetaldehyde removal was measured and an almost tenfold enhancement of the quantum yield was observed for the TiO₂/TiAlN films compared with the single TiO₂ film, on par with enhancements achieved with new heterojunction photocatalysts. The results were interpreted by a temperature-induced change of the reaction kinetics. Absorption of simulated solar light illumination resulted in a temperature increase of the TIAlN film that was estimated to be at most 126 K. We show that a concomitant temperature increase of the top layer TiO₂ by 100 K shifts the water gas-surface equilibrium from multilayer to submonolayer coverage. We propose that this is the main reason for the observed enhancement of the photocatalytic activity, whereby gas phase molecules may come in direct contact with free surface sites instead of having to diffuse through a thin water film. The implications of the results for judicious control of temperature and relative humidity for efficient gas-phase photocatalysis and exploitation of selective solar absorbing films are discussed.     

Characterization of absorptivities to solar radiation for colored pigments in coatings

Colored pigments absorptivities to solar radiation have been characterized quantitatively by measuring the absorption coefficients of the colored pigments mixed in white titanium dioxide standard coating. The standard coating contains white TiO₂ with 17% pigment volume concentration (PVC). Dry white coating with more than 134 μm thickness is opaque and used as a dispersion medium for colored pigments. The reflectances of the coatings of white TiO₂ and three kinds of colored pigments (perylene black, toluidine red, and benzidine yellow) to solar radiation are measured by means of a UV-3100 recording spectrophotometer operating in the 250∼2500 nm spectral range. It is found that the plots of lg 1/R (R, reflectance of coating to solar radiation) againstV _coloredV_{Ti0 2} (volume ratio of the colored pigment to TiO₂ in coating) are straight lines of increasing slopes in the range ofV _coloredV_{Ti0 2} less than five percent. From the slopes of the straight lines, the absorption coefficients of colored pigments can be measured quantitatively. Beijing, 100029, China. Email: guohy@public.fhnet.cn.net.     

Synthesis of Ni,N co-doped TiO<Subscript>2</Subscript> using microwave-assisted method for sodium lauryl sulfate degradation by photocatalyst

A titanium dioxide (TiO₂) photocatalyst was modified with nickel (Ni) and nitrogen (N) in titanium tetra-isopropoxide (TTIP) as a precursor through a microwave-assisted method. The Ni and N dopants led to a decrease in the TiO₂ band gap and made it able to function with visible light irradiation. The results of X-ray diffraction analysis demonstrated that the crystalline size of Ni–N–TiO₂ was 13.275 nm in anatase form with a specific peak in 2θ = 25.32°. Ni–N–TiO₂ was analyzed by scanning electron microscopy, which showed the smaller morphology and thin particles, and this was further supported by energy-dispersive X-ray data regarding the elemental composition of Ni and N being 4.50 and 2.39%, respectively. Fourier transform infrared spectroscopy results demonstrated the absorption spectrum in wavenumbers of 1197 and 1149 cm^?1, indicating an N–TiO₂ bond, a Ti–O bond at 648 cm^?1, and an Ni–O bond at 469 cm^?1. TiO₂ modified by Ni and N exhibited a decrease in the band gap at 1.95 eV, suggesting the Ni and N dopants successfully inserted onto the TiO₂ crystalline surface to be visualized with visible light. Photoactivity testing was carried out to degrade sodium lauryl sulfate surfactants under visible irradiation, where the degradation efficiency was 93.75%.     

Removal of atrazine by photoelectrocatalytic process under sunlight using WN-codoped TiO<Subscript>2</Subscript> photoanode

The present study was focused on the degradation of Atrazine (ATZ) and major by-products (DEA, DIA, DEDIA and ATZ-OH) from water by photoelectrocatalytic (PEC) oxidation process under solar light. The undoped TiO₂, sub-stoichiometric TiO₂ (TiO_2?x) and codoped TiO₂ (TiO₂:WN) photoanodes were prepared by means of a radio frequency magnetron sputtering (RF-MS) deposition process. The X-ray photoelectron spectra (XPS) analysis shows that the N and W atoms were incorporated into the O and Ti lattice sites of TiO₂ respectively (case of TiO₂:WN film), while the XPS measurements of the TiO_2?x films composition was determined to be TiO_1.9. The UV–Vis transmittance spectra shows that in the case of the TiO₂:WN films, the presence of nitrogen and tungsten improve the optical response of TiO₂ under visible range compare to the presence of oxygen vacancies in to the TiO_2?x films. The experimental results under solar light with an initial concentration of ATZ (100 µg L^?1) show that after 180 min of treatment, the degradation of ATZ were 34.98%, 68.57% and 94.33% using TiO₂, TiO_2?x and TiO₂:WN photoanodes, respectively. These results of ATZ degradation proved that TiO₂:WN photoanode was more photoactive under solar light. The evolution by-products of ATZ under sunlight show that the principal mechanism of ATZ degradation was the oxidation of alkyl side chain and dealkylation.

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Synthesis and Photocatalytic Performance of Bi<Subscript>12</Subscript>O<Subscript>17</Subscript>Cl<Subscript>2</Subscript> Semiconductors Calcined at Different Temperatures

In the current investigation a series of oxygen-rich bismuth oxychloride Bi₁₂O₁₇Cl₂ samples through an ethylene glycol-solvothermal route were constructed at different calcination temperatures and fully characterized by X-ray diffraction patterns, scanning electron microscopy, Fourier transformed infrared spectroscopy, X-ray photoelectron spectroscopy, UV–Vis diffuse reflectance spectra, X-ray energy dispersion spectroscopy, and photoluminescence spectra. It was demonstrated that the calcination temperatures indeed had a crucial effect on the crystallinity, grain size, morphology, optical property, and charge carrier separation of Bi₁₂O₁₇Cl₂ series. These Bi₁₂O₁₇Cl₂ samples showed significantly improved photocatalytic degradation over dye Rhodamine B and colorless antibiotic tetracycline hydrochloride. Particularly, the best candidate, the sample 350 °C—Bi₁₂O₁₇Cl₂ could show apparent reaction rate constants that were nearly 28.2, 1.2 times of N–TiO₂ over Rhodamine B and tetracycline hydrochloride, respectively. The possible reason of enhancing photocatalytic performance by various Bi₁₂O₁₇Cl₂ samples calcined at different temperatures was discussed and major oxidative radicals maybe generated during photocatalytic processes were detected.     

Solar photocatalytic detoxification of cyanide by different forms of TiO<Subscript>2</Subscript>

The photocatalytic efficiencies of TiO₂ nanocrystals of different modifications (anatase, rutile, P25 Degussa, Hombikat), to oxidize cyanide ion and subsequently the cyanate also, under natural sunlight at 950±25W m⁻² in alkaline solution have been compared. The oxides have been characterized by powder XRD, UV-visible diffuse reflectance and impedance spectroscopies. Under identical solar irradiance, the reaction follows Langmuir-Hinshelwood kinetics on cyanide, and depends on the apparent area of the catalyst bed and dissolved oxygen. However, the adsorption of cyanide on TiO₂ in dark is too small to be measured analytically. The photocatalytic activity of TiO₂ is not solely governed by the band gap or charge-transfer resistance or capacitance or phase composition but is in accordance with the specific surface area or the average crystallite size; rutile is an exception.     

Preparation of TiO<Subscript>2</Subscript>/SiO<Subscript>2</Subscript> composite oxide and its photocatalytic degradation of rhodamine B

The composite semiconductor photocatalyst TiO₂/SiO₂ was prepared by template-hydrothermal method using carbon spheres as the template. The structural and optical properties of TiO₂/SiO₂ were characterized by XRD, SEM, BET, UV–Vis DRS, TG-DTA, PL techniques. The formation of hydroxyl radical on the surface of TiO₂/SiO₂ was studied with terephthalic acid as the probe molecule, combined with fluorescence technique. The results showed that the specific surface area of TiO₂/SiO₂ composite was 327.9 m²/g, and the specific surface area of TiO₂/SiO₂ was larger than that of pure TiO₂. Photocatalytic degradation of rhodamine B showed that TiO₂/SiO₂ composite oxide under visible light illumination 40 min, the degradation rate was 98.6 % and the degradation rate of pure TiO₂ was only 11.9 %. The apparent first-order rate constant of TiO₂/SiO₂ was 33 times that of pure TiO₂ and more than 6 times that of P25 when the molar ratio of Ti to Si was 1:1 under visible light irradiation. Moreover, it’s also as much as 5 times that of pure TiO₂ and is more than 1 times that of P25 under UV light irradiation 25 min. Based on the experimental results, ^·O₂ ^? and h⁺ were suggested to be the major active species which was responsible for the degradation reaction. The increased photocatalytic activity of TiO₂/SiO₂ may be mainly attributed to effectively suppressing the recombination of hole/electron pairs. After the photocatalyst TiO₂/SiO₂ was reused 5 times, the degradation rate of rhodamine B could reach 89.2 % under visible light irradiation. Moreover, The composite semiconductor photocatalyst TiO₂/SiO₂ was selective towards the degradation of rhodamine B.     

Hydrolytic Degradation and Morphological Characterization of Electrospun Poly(glycolic acid) [PGA] Thin Films of Different Molecular Weights Containing TiO<Subscript>2</Subscript> Nanoparticles

Thin films of polyglycolic acid (PGA), a biodegradable and biocompatible polymer, were prepared by electrospinning and were studied according to their molecular weights. TiO₂ nanoparticles were also used as additives at concentrations of 2–8 wt%. The films were morphologically characterized and exhibited a homogeneous distribution of TiO₂ with only slight differences depending on the molecular weight. In particular, fibers with low-molecular-weight PGA were thinner and had an average diameter of 77 nm. Furthermore, they showed a higher resolution of the TiO₂ crystal planes regardless of the crystal habit involved. During the melting of the PGA fibers, one single and prominent melting endotherm was observed, which was independent of molecular weight, TiO₂ content, and crystal phase involved. This was in contrast to quiescent PGA crystallization and melting, during which the typical double melting behavior was present. After thermal measurements, TiO₂ did not show characteristics of a nucleating agent for the PGA fibers. However, it acted as a degradation retardant for low-molecular-weight PGA. Because of its hygroscopicity, anatase, a material with the ability to absorb water, was a more efficient hydrolytic degrader than rutile.     

The role of graphene and europium on TiO2 performance for photocatalytic hydrogen evolution

Highly efficient Eu-TiO₂/graphene composites were synthesized by a two-step method such as sol-gel and hydrothermal process. The synthesized photocatalysts were characterized by XRD, TEM, XPS, UV–vis diffuse reflectance spectroscopy and photoluminescence (PL) spectroscopy. The results confirmed that anatase Eu-TiO₂ nanoparticles with average 10 nm sizes were successfully deposited on two-dimensional graphene sheets. The UV–visible spectroscopy showed a red shift in the absorption edge of TiO₂ due to Eu doping and graphene incorporation. Moreover, effective charge separation in Eu-TiO₂/graphene composites was confirmed by PL emission spectroscopy compared to TiO₂/graphene, Eu-TiO₂ and pure TiO₂. The photocatalytic activity for H₂ evolution over prepared composites was studied under visible light irradiation (λ ≥ 400 nm). The results demonstrate that photocatalytic performance of the photocatalysts for hydrogen production increases with increasing doping concentration of Eu upto 2 at%. However, further increase in doping content above this optimum level has decreased the performance of photocatalyst. The enhanced photocatalytic performance for H₂ evolution is attributed to extended visible light absorption, suppressed recombination of electron-hole pairs due to synergistic effects of Eu and graphene.     

Synthesis and characterization of polythiophene/titanium dioxide composites

Polythiophene/titanium dioxide (PT/TiO₂) composites were prepared by the in situ chemical oxidative polymerization method. The resulting PT/TiO₂ composites were characterized by Fourier transform infrared (FT-IR) spectroscopy, ultraviolet–visible (UV–Vis) diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and field emission scanning electron microscopy (SEM). UV–Vis diffuse reflectance spectra measurements show that the PT/TiO₂ composites can adsorb light of wavelengths ranging from 200 nm to 800 nm. The PT/TiO₂ composites showed good adsorption properties and were more efficient in removing dye from solution than pure PT and pure TiO₂. The PT/TiO₂ composites exhibited photocatalytic activities to some extent under UV light illumination.     

The effect of TiO2 morphology on the surface modification of poly (ethylene terephthalate) for electroless plating

In this study, a surface modification of the poly (ethylene terephthalate) (PET) film using TiO₂ photocatalytic treatment was investigated. In order to enhance the adhesion strength between the PET film and the electroless copper film, the effects of TiO₂ crystal forms, TiO₂ particle sizes, and TiO₂ content, as well as treatment condition, upon the surface contact angle, surface characterization, and adhesion strength were investigated. Anatase TiO₂ with a particle size of 5 nm had a high catalytic activity and dispersibility in aqueous solution. After the optimal photocatalytic treatment, the surface contact angle of the PET film decreased from 84.4° to 19.8°, and the surface roughness of the PET film increased from 36 to 117 nm. The adhesion strength between the PET film and the electroless copper film reached 0.89?KN?m^?1. X-ray photoelectron spectroscopy analyses indicated the carbonyl group was formed on the PET surface after photocatalytic treatment, and the surface hydrophilicity was improved. Consequently, TiO₂ photocatalytic treatment is an environmentally friendly and effective method for the surface modification of the PET film.