Anti-ultraviolet treatment by functionalizing cationized cotton with TiO 2 nano-sol and reactive dye

Abstract

A new approach for ultraviolet (UV) protection of cotton fabrics based on TiO₂ nano-sol and reactive dye was studied. Cotton fabrics were cationized with different amounts of 3-chloro-2-hydroxypropyl trimethylammonium chloride. TiO₂ nano-sol was prepared by the sol-gel method using tetraisopropyl orthotitanate and applied on cationized cotton fabrics with different quantities using the same finishing formulation and treatment sequence. Treated fabrics were then dyed with various concentrations of BH-3RS-Reactive yellow 176. Samples were further tested for UV protection factor, color strength, color fastness to washing, durability and tensile strength. The chemical and morphological structures of the coated fabrics were characterized by attenuated total reflection–Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffractometry. Cationized cotton fabrics treated with TiO₂ nano-sol and dyed with reactive dye showed better UV protection with slight reduction in color depth (K/S) and tensile strength.

Keywords

ultraviolet protection reactive dyeing

Protecting human skin against harmful ultraviolet radiation (UVR) is an acute problem nowadays. Due to decreased thickness of the ozone layer, more UV light reaches the ground. Long-term exposure to UV light can result in a series of skin conditions, such as acceleration of skin ageing, photodermatosis (acne) and even skin cancer.¹

The UVR consists of three ranges: UV-A (315–400 nm), UV-B (290–315 nm) and UV-C (100–290 nm). The UV-C radiation is absorbed by the ozone layer, however, the UV-A and UV-B reach the Earth’s surface and cause serious health problems. Therefore, the main UVRs that should be blocked by textiles are UV-A and UV-B.² Numerous approaches have been investigated to improve the UV protection of cotton fabrics because cotton textiles are the most regular summer clothes but have the least UV blocking ability.^1,3

Several factors affect the ability of fabrics to provide adequate protection from UVR, such as fabric construction, chemical composition, textile auxiliaries, color and finishing process.^2,3

Dyes often provide a good blocking effect of UV light transmittance. Srinivasan and Gatewood⁴ conducted an extensive study on the relationship between dye characteristics and UV protection provided by cotton fabric. Their results showed that color is not a reliable indicator of the UV protection provided by dyed fabrics.

In recent years, considerable research and development efforts have been devoted to improve the UV protection function of cotton fabric against the harmful UVR using UV blockers such as TiO₂, ZnO and SiO₂ nanoparticles.^2,5

TiO₂ has been the subject of numerous investigations in diverse fields due to its non-toxicity, high photocatalytic efficiency, physiochemical stability and affordability.^6–9

TiO₂ nanoparticles have been applied on cotton fabrics through the sol-gel technique to improve the ultraviolet protection factor (UPF) and efforts have been made to enhance the durability of the UV protection during the laundering process.^10–13

Farouk and Abd El-Hady¹⁴ developed a simple treatment to impart UV protection to cotton fabric by means of cationizing cotton fabric that was further treated with BTCA/TiO₂ nanoparticles or BTCA/TiO₂/SiO₂ nanomaterials.

Ibrahim et al.³ applied a new approach for attaining reactive prints on cotton/wool and viscose/wool with outstanding UV protection functions. UV absorbers and UV blockers, such as ZnO and TiO₂ nanoparticles, were incorporated with monochlorotriazinyl β-cyclodextrin in the printing paste. Experimental results revealed that the inorganic UV blockers exhibit better UV protection functions compared with the used UV absorbers.

The aim of this work is to apply TiO₂ nanoparticles with reactive dye on cationized cotton fabrics for obtaining durable protection properties against harmful UVR. Cationized cotton fabrics were subjected to different amounts of TiO₂ nano-sol and various dye concentrations to determine the best formulation that can be applied to cotton fabric and provoke higher fabric performance. The ability of UV blocking and its durability after 10 laundering cycles were investigated. Color strength, washing fastness and tensile strength were also investigated.

Experimental details

Materials and chemicals

Tetraisopropyl orthotitanate (C₁₂H₂₈O₄Ti) was supplied by Ourchem Sinopharm Chemical (Shanghai-China), 3-chloro-2-hydroxy propyl trimethylammonium chloride was supplied by Aladdin Industrial Corporation (Shanghai-China) and BH-3RS-Reactive yellow 176 was supplied by Ningbo Friendship Dye Co. Ltd (China). The fabric used in this study was desized, scoured and bleached 100% cotton. All chemicals were used as received without further purification. Deionized water was used throughout the study.

Sample designation

The samples were designated as shown in Table 1.

Preparation of TiO₂ nano-sol

The aqueous TiO₂ nano-sol was prepared at room temperature by mixing tetraisopropyl orthotitanate (C₁₂H₂₈O₄Ti) (10 g) with glacial acetic acid (50 ml drop wise), absolute ethyl alcohol (100 ml drop wise) and distilled water (50 ml), followed by vigorously stirring for 1 hour.¹⁵

Cationization of cotton fabrics

Cotton fabrics were cationized based on the pad-batch method. Different amounts (75, 50 and 25 g) of 3-chloro-2-hydroxy propyl trimethylammonium chloride were dissolved in 200 ml deionized water. Sodium hydroxide (34.13, 22.8 and 11.4 g) was then added to form 2,3-epoxypropyltrimethylammomium chloride (EP₃MAC) solution. Afterward fabrics were impregnated with 2,3-epoxypropyltrimethylammomium chloride (EP₃MAC) solution at 50℃ for 20 min. EP₃MAC reacts with the hydroxyl groups of cellulose creating cationic charges on the surface of the fabrics. Samples were then padded at a speed of 1 m/min and pressure of 1 kg/cm². The padded fabrics were wrapped in plastic films for 24 h at room temperature to prevent the migration of chemicals on the fabrics and evaporation of water. Afterwards, the fabrics were rinsed twice with distilled water and neutralized with acetic acid solution (2 g/l). Finally, the treated fabrics were rinsed to obtain a pH of 7.2 and then dried in a commercial dryer at 60℃.^16,17

Treatment of cationized cotton with TiO₂ nano-sol

Cationized cotton fabrics were treated with different amounts (10, 20 and 30 ml) of TiO₂ nano-sol. Samples were immersed into TiO₂ nano-sol without cross-linking agents at ambient temperature for 10 min. Then the samples were padded at 1 kg/cm² and dried at 60℃ for 10 min to evaporate the ethanol. Subsequently, the samples were cured at 150℃ for 5 min and rinsed to remove the unattached TiO₂ nanoparticles, after which they were dried.¹⁵

Dyeing of treated samples with reactive dye

Treated samples were dyed with BH-3RS-Reactive yellow176 at different concentrations (1%, 2% and 3%), using an exhaustion method in a model gy-12/HTAI-Hua Tai-China dyeing machine. Samples were dipped in the dye solution at 40℃ for 20 min with a liquor ratio of 1:20. The temperature was raised to 60℃ at a rate of 2℃/min; afterward, sodium carbonate was added to the dyeing bath and dyeing continued for 40 min. Finally, the samples were boiled with the soap, washed and dried.

Test and analysis

Nano particle size and zeta potential test

A particle size and zeta potential analyzer (Malvern Instrument Ltd, England) was used to determine the size and zeta potential of TiO₂ nanoparticles.

UV protection measurement

A spectrophotometer was used to evaluate the UV protection by measuring the UVR transmittance of each fabric across the wavelength range 280–400 nm, which includes the UV-A and UV-B.¹⁴ The UPF was obtained using Ultraviolet Transmittance Fabric Analyzer Labsphere (USA).

Color strength (K/S value)

The color strength of the dyed fabrics (K/S) was measured using a Datacolor SP600⁺ spectrophotometer (Datacolor Co., USA), at wavelength 440 nm.

Washing fastness

Washing fastness was carried out in SW-12 A Tester for color fatness to washing (Wenzhou Darong Textile Instrument Co. Ltd, China) in accordance with the ISO 105-C10 (2006) standard, using 3 g/l of standard soap at 60℃ for 30 min and then drying at 60℃.¹¹ Thereafter, the change in color of specimens and stains of the adjacent fabrics were assessed with a Datacolor SP600⁺ Spectrophotometer.

Durability test

The treated fabric samples were subjected to 10 laundering cycles according to ISO 105-C10 (2006) to determine the anti-UV durability to washing.

Tensile strength

Tensile strength was measured in the warp direction using the Material Testing Machine, H10K-S (Tiniius Olsen, USA), according to ASTM-D5034-95. The obtained data were the average of three tests and reported as the average ± standard deviation.

Attenuated total reflection–Fourier transform infrared analysis

A Varian 640-IR Fourier transform infrared (FT-IR) spectrometer was used to measure the changes in the characteristic groups on the fabric surface. The attenuated total reflection–Fourier transform infrared (ATR-FTIR) spectra (64scans, 4 cm⁻¹ resolution) were recorded using a single reflection horizontal ATR accessory with a spherical Ge crystal.

X-ray diffraction

X-ray diffraction (XRD) patterns of TiO₂ nanoparticle-coated cotton fabrics were recorded on an X-ray diffractometer D/MAX-2250 (Rigaku, Japan).

Scanning electron microscope

The scanning electron microscope (SEM) images of the samples were obtained using a TM-1000 HITACHI microscope. Fabric samples were mounted onto an aluminum stub and coated with gold by means of thermal evaporation in a vacuum-coating unit and then examined in the SEM at an accelerating voltage of 10 kv. The SEM photographs were obtained with a magnification in range of the 500×, 1000× and 1500×.

Results and discussion

Preparation of TiO₂ nano-sol

TiO₂ nano-sol was prepared using the sol-gel method by means of hydrolysis of tetraisopropyl orthotitanate in the presence of acetic acid and ethanol as catalysts. The size obtained was in range of 0.01–78.82 nm, the polydispersity index (PdI) of TiO₂ nanoparticles was 0.33 and the intensity was 98.7%.

A particle size and zeta potential analyzer was used to determine the zeta potential of TiO₂ nano-sol. Three readings were recorded (0.0589 mv, −0.023 mv and −0.216 mv). The result indicates that TiO₂ nano-sol has positive and negative charges and this may increase the interaction between TiO₂ nano-sol and cationized fabrics, as well as reactive dye.

UV protection measurement

When the fabric is treated with titanium dioxide nano-sol, using the synthesized by sol-gel method, the formation of particles on the fabric surface imparts very good and efficient UVR scattering because of the refractive index of TiO₂.¹⁷

Figure 1 shows the effect of the treatment on the UPF of the cotton fabrics. The UPF of the fabrics depends on the fiber content, weave, used dyes and finishing processes, and should be between 40 and 50+ to categorize the clothing cotton fabrics with an excellent UV protection.² Based on this criteria, blank plain-weave cotton fabric with UPF rating 10 is classified as non-ratable fabric with inadequate protection for outdoor wearers. After treatment with TiO₂ and dyeing, the UPF values of all the samples were increased rapidly. Furthermore, it can be reported that the UPF values of cationized samples treated with TiO₂ increased after dyeing with the reactive dye, regardless of the dye concentration. As demonstrated in the literature,¹⁸ dyestuffs can generally increase the UPF. However, color is not a reliable indicator of the UV protection provided by dyed fabrics.² Compared with untreated fabric, the UPF values of cationized, treated and dyed samples had better UPF values with different amounts (25, 50, 75 g) of cationizing agent, different amounts (10, 20, 30 ml) of TiO₂ nano-sol and different dye concentrations (1%,2% and 3%). The UPF value of sample A was increased by 39.5% after treatment and dyeing, higher than that of cationized dyed fabric, which was increased by 37.1%. In addition, the UPF of sample B was increased by 42% after treatment and dyeing compared with 26.65% of the cationized dyed sample, while the increase in UPF of sample E was 38.44% after treatment and dyeing compared with 26.6% of the cationized dyed sample. Furthermore, the UPF of sample D was increased by 44.8% after treatment and dyeing, compared with 26.6% of the cationized, dyed sample. As shown in Figure 1, cationized dyed samples had a relatively high UPF, due to the cationization of the cotton surface before the dyeing process. The highest increasing rate of UPF was obtained with sample D, due to the utilization of the highest amount (30 ml) of TiO₂ nano-sol in treatment. From the results it can be concluded that the UV-blocking property of the cationized cotton treated with TiO₂ nano-sol improved remarkably even at low TiO₂ nano-sol content.¹⁴

Figure 1.

Ultraviolet protection factor (UPF) of samples A, B, C, D, E, F and G.

The durability of the treated samples was investigated (Figure 1). The UPF values of all treated samples showed slight reduction after 10 laundering cycles and this is indicative of a good adhesion between the TiO₂ nano-sol and the fabric surface. The durability of the treatment could be attributed to the formation of covalent linkages between many hydroxyl groups of cellulose and the hydroxyl groups of the TiO₂ network.² In addition, the numerous accessible hydroxyl groups of the cellulose surface can enhance the diffusivity of adsorbed TiO₂ nanoparticles and transfer of hydrogen from TiO₂ to the cellulose and its interaction with cellulose substantially increased laundering durability.¹⁹

Color strength test (K/S values)

Figure 2 shows the influence of cationization, nanoparticles and dyeing on the color strength of the cotton fabrics. The wavelength used for recording the K/S values of dyed samples was 440 nm. As shown in Figure 2, the color strength values decreased slightly after treatment with TiO₂ nano-sol. The K/S values of the cationized, treated and dyed samples (A, B, C and D) were found to be higher than that of the control sample (S). These results could be attributed to the cationic modification of the fibers and covalent bonding. In addition, some reactive dye molecules were absorbed into the fiber by electric adsorption.¹³

Figure 2.

Color strength (K/S) of samples S, H, A, B, C, D and E treated and untreated, dyed with reactive dye.

Sample A had the best color strength (12.1) compared with B (9.2) and C (9.8). Sample H, treated with TiO₂ without cationization, had the lowest color strength (6.44). The color strength of sample D was the lowest compared with other cationized, treated samples and that may be ascribed to the highest amount (30 ml) of TiO₂ nano-sol used in treatment. Hence, it can be observed that increased amount of TiO₂ nanoparticles formed an undesirable complex between dye molecules and particles according to electrostatic interaction. Therefore, it can limit the dye diffusion.¹⁹ They can also deposit on the fabric surfaces and filter the other dye molecules. It can be concluded that the color strength of all the treated and dyed samples did not change noticeably. These results indicate that the chromophore groups of the reactive dye are not damaged and the conjugated system is unaffected by coating with TiO₂nano-sol.

Washing fastness

Table 2 shows the color fastness to washing (color change and color staining); it can be reported that all samples have excellent washing fastness, which is one of major requirement of a textile material.^2,19 The durability of the treated samples could be attributed to the formation of covalent bonding between the hydroxyl groups of TiO₂ nanoparticles and hydroxyl groups of cotton, as well as the covalent bonds between the dye and the cotton fabric.¹⁹

Table 1.

Application of TiO₂ and reactive dye on cotton fabric using the orthogonal method

Sample	Cationizing agent amount/g	TiO₂ nano-sol amount/ml	Dye concentration/%
A	75	20	3
B	50	20	3
C	25	20	3
D	50	30	3
E	50	10	3
F	50	20	2
G	50	20	1
S	None	None	3
H	None	20	3

Table 2.

Effect of cationization/nanoparticles and dyeing on color fastness to washing (color change and color staining)

Samples	Color change	Color staining
A	4/5	4/5
B	4/5	4/5
C	4/5	4/5
D	4/5	4/5
E	4/5	4/5
F	4/5	4/5
G	4/5	4/5

Tensile strength

The influence of the cationization, dyeing and TiO₂ nanoparticles on the tensile strength of the treated fabrics was investigated and the corresponding data are given in Table 3. It can be determined that the tensile strength of all treated samples is slightly decreased compared with untreated cotton fabric.

Table 3.

Effect of cationization/nanoparticles and dyeing on the tensile strength

Sample	Tensile strength (daN) ± standard deviation (daN)
Untreated cotton fabric	83.9 ± 1.01
A	81.1 ± 0.8
B	80.9 ± 1.03
C	81.4 ± 0.96
D	80.2 ± 1.05
E	82.1 ± 0.92

ATR-FTIR analysis

The spectrum of a blank cotton sample with many free hydroxyl groups on the surface shows characteristic bands at 3200–3500 cm⁻¹ due to O-H vibration of water, at 2800–1980 cm⁻¹ due to C-H stretching and at ∼1645 cm⁻¹ due to the deformation vibration of water molecules and absorption bands in the 800–1500 cm⁻¹ spectral region, which occurred as result of C-H, OH and C-O-C vibrations.¹⁹

The changes in many ATR-FTIR bands characteristic of cotton cellulose (Figures 3 and 4) reflect the occurrence of the TiO₂ modification through the hydrogen bonds, as well as the electrostatic interaction between TiO₂ and cellulose during the reactive dyeing.¹⁹

Figure 3.

Attenuated total reflection–Fourier transform infrared spectra of blank cotton, and cationized treated sample.

Figure 4.

Attenuated total reflection–Fourier transform infrared spectra of cationized fabrics treated with (30, 10 ml) of TiO₂ nano-sol and dyed with reactive dye (3%).

The symmetric O-Ti-O stretch band of the treated sample and treated, dyed samples appeared at ∼613 cm⁻¹ (Figure 4). The O-Ti-O band in the sample that was treated with 30 ml of TiO₂ nano-sol is deeper than that treated with 10 ml, although both samples were dyed with the same concentration of reactive dye, which might suggest that there is no tangible effect of concentration of the reactive dye on the TiO₂ nanoparticles.

X-ray diffraction

Figure 5 shows the XRD patterns of the untreated sample, cationized treated sample and cationized treated, dyed sample. It can be observed that the peak associated with the anatase phase appeared at (2θ = 20.8°) in the cationized treated sample as well as in the cationized, treated, dyed sample. Furthermore, it can be observed that the major peak of TiO₂ in the cationized treated sample is stronger than that of the cationized treated, dyed sample.

Figure 5.

X-ray diffraction pattern of the cationized treated sample; cationized, treated, dyed sample; and untreated sample.

Scanning electron microscope

Fiber surface morphology of the cationized samples treated with different amounts (10, 20 and 30 ml) of TiO₂ nano-sol and dyed with various concentrations (1%, 2% and 3%) of reactive dye are shown in Figure 6.

Figure 6.

Scanning electron micrographs of treated samples: (1) cationized, treated; (2) cationized, treated, dyed.

From the images in Figure 6 it can be observed that the TiO₂ nanoparticles dispersed clearly onto the surface of all the samples. Even after dyeing, the TiO₂ nanoparticles were still attached on the fibers, regardless of the dye concentration, amount of TiO₂ nano-sol or the amount of cationizing agent. This could be attributed to a good adhesion between the nanoparticles and the fabric due to the hydrogen bond as well as electrostatic force between the cationized samples, nanoparticles and reactive dye.

Conclusion

Treatment of cotton fabric with 3-chloro-2-hydroxy propyl trimethylammonium chloride was proven to create a positively charged substrate. Incorporation of TiO₂ nano-sol in the reactive dyeing process resulted in hydrogen bonding of the TiO₂ nanoparticles onto the cotton fabrics, in addition to the covalent bond and the electrostatic bond between the cationized cotton, reactive dye and TiO₂. The FT-IR test revealed that the O-Ti-O peak appears on the treated sample as well as on the treated, dyed samples, which proves the existence of TiO₂ nanoparticles even after the dyeing process. The XRD pattern of treated and treated, dyed samples showed the major peak is the anatase phase (2θ = 20.8°). Moreover, the SEM revealed a clear dispersion of TiO₂ nanoparticles on the surface of the treated and treated, dyed samples. The UPF of the treated dyed samples was higher than that of untreated dyed samples.

This treatment imparted durable UV protection even after 10 laundering cycles, and there was minimal impact on the color depth (K/S) and tensile strength. Finally, it can be concluded that application of TiO₂ nano-sol with reactive dye can be a helpful combination to achieve durable UV protection properties without affecting other performance properties.

Footnotes

Funding

This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

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Anti-ultraviolet treatment by functionalizing cationized cotton with TiO 2 nano-sol and reactive dye

Abstract

Keywords

Experimental details

Materials and chemicals

Sample designation

Preparation of TiO2 nano-sol

Cationization of cotton fabrics

Treatment of cationized cotton with TiO2 nano-sol

Dyeing of treated samples with reactive dye

Test and analysis

Nano particle size and zeta potential test

UV protection measurement

Color strength (K/S value)

Washing fastness

Durability test

Tensile strength

Attenuated total reflection–Fourier transform infrared analysis

X-ray diffraction

Scanning electron microscope

Results and discussion

Preparation of TiO2 nano-sol

UV protection measurement

Color strength test (K/S values)

Washing fastness

Tensile strength

ATR-FTIR analysis

X-ray diffraction

Scanning electron microscope

Conclusion

Footnotes

Funding

References

Preparation of TiO₂ nano-sol

Treatment of cationized cotton with TiO₂ nano-sol

Preparation of TiO₂ nano-sol