- Email: [email protected]
Controllable wavelength-selective optical composite based on nano-polymeric films with doped dyes
Composites Science and Technology 172 (2019) 1–6
Contents lists available at ScienceDirect
Composites Science and Technology journal homepage: www.elsevier.com/locate/compscitech
Controllable wavelength-selective optical composite based on nanopolymeric films with doped dyes
T
Aiqin Gaoa, Danna Fua, Aiqin Houb, Kongliang Xiea,∗ a b
College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, PR China National Engineering Research Center for Dyeing and Finishing of Textiles, Donghua University, Shanghai, 201620, PR China
A R T I C LE I N FO
A B S T R A C T
Keywords: Polymeric nanoparticles Controllable light absorption Solar energy Dye-doped Selectively transmittance
The novel color optical composites with controllable light absorption from the solar energy based on polyvinyl alcohol (PVA) as matrix materials were investigated. The nanoparticles with molecular level dye-doped were prepared by microemulsion polymerization. The structure and morphology of the nanoparticles and the color nano-films were characterized by Fourier transform infrared spectrum (FT-IR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray powder diffraction (XRD) analysis. Three nanoparticles with dye-doped are all homogeneous nanospheres with regular shape and size of 50–70 nm. Three PVA color films containing nanoparticles possess different absorption bands in the visible light region. A controlled sunlight absorption film filter using dye-doped nanoparticles can be arbitrarily designed and assembled by adjusting the recipe to selectively transmit specific wavelengths from sunlight. Because the dye molecules are stabilized in the nanoparticles, the absorption band of the membranes can be precisely controlled. It can be conveniently assembled or deposited on other substrates to form nano-membranes. The composite containing color nanoparticles is simple, flexible, and cost-effective. They have potential applications in many fields, such as energy, agriculture, environment and biotechnology.
1. Introduction Solar energy has always been the most promising renewable energy. In recent years, how to make full use of solar energy has become an important research field [1–3]. The researches for the acceptance and conversion of solar energy based on nano-composites are being increased owe to their widely applications [4–6]. The selecting absorption sunlight composites based on the polymer matrix have been widely paid attention in the energy, agriculture, environment, biotechnology, medical diagnosis, food, and other high-technology fields, which are demonstrated to be crucially important tools in many novel applications [7–9]. For example, microalgae are a group of photosynthetic organisms, which can rapidly grow under certain light wavelengths from the selecting sunlight spectra. The wavelength of the light source also plays an important role in the algal culture. According to the experience of agriculture and marine farming, each plant or microalgae need a specific wavelength of light to grow. The certain spectrum can be regulated according to the sensitivity of the plants to light. The nanocomposites, which can select transmit certain wavelength light from natural sunlight, significantly improve biomass yield [10,11]. Most often natural sunlight is not optimized for some plant cell growth due to
∗
the wide light spectra including ultra-violet (UV) and infrared red (IR) rays, which can damage the cellular structure. The efficiency of photosynthesis can be improved by the selecting absorption of spectral light [12,13]. There are very important applications in agriculture, ocean, environment, and biotechnology, especially the ones requiring the processing on large areas with costs. The optical devices based on doped polymer matrix are gaining attention and potentially applied in laser, medical imaging, photonic devices, spectral light filters [14–16]. The doped polymer membranes with special optical properties have become a hot research field. Some dopants, such as semiconducting or metal nanoparticles, and dyes can directly influence the optical properties of the polymer films. The spectral light filters can be designed by using various polymer materials and various chromophores. The advantages of polymer-based molecular systems are their low cost and easily modified to match the specific needs. However, the composite films with dopants have their disadvantages, such as transmission band is not easy to arbitrarily design and regulate, especially in the visible band [17–19]. Among these novel materials, dye-doped polymer thin films are expected as candidates of cost-effective, simple and cheap fabrication technologies. Of course, polymeric matrix would restrict the activity to optical sources.
Corresponding author. E-mail address: [email protected] (K. Xie).
https://doi.org/10.1016/j.compscitech.2019.01.001 Received 18 July 2018; Received in revised form 30 December 2018; Accepted 1 January 2019 Available online 04 January 2019 0266-3538/ © 2019 Elsevier Ltd. All rights reserved.
Composites Science and Technology 172 (2019) 1–6
A. Gao et al.
amount of the initiator, ammonium persulphate, 0.15%, was slowly dropped into the microemulsion. The polymerized reaction was carried out for 4 h at 85 °C. The color polymeric nanoparticle colloid was obtained.
So, the matrix materials should be transparent, non-absorption light and cheap. Dye-doped polymer composites can generate designing absorption in the specific spectral regions or emission on the whole visible spectral region [20–22]. Among all kinds of dyes, disperse dyes, similar with organic pigments, are almost insoluble in water, which are the crystals precipitated from water or other organic solvent [23,24]. However, it is difficult to shatter and disperse into molecules in the polymer films. The milling method represents one of the most popular approaches to produce the required powder particles by means of wet grinding process. Due to the hydrophobic character and high surface energy of the dye particles, they tend to aggregate into bigger particles [25,26]. It is important to investigate nano-dispersive technology or prepare molecule-sized particles to prevent the agglomeration of the disperse dyes. Nanomaterials and nano-dispersive technology have become a research hotspot in the advanced materials, colloid and interface fields. Several methods have been reported for the nano-dispersive dyes, such as dispersion, emulsion, and miniemulsion polymerization [27,28]. However, most dyes exist in these systems with dye aggregates, which can further affect the selective absorption property of solar spectrum. We note that the disperse dyes are insoluble in water, but they can dissolve in organic monomer of polymer in molecules. In this paper, the mixture monomers of methyl methacrylate (MMA) and butyl acrylate (BA) as organic solvent were used to dissolve the dyes, then nano-emulsify. Three dispersive dyes with different absorption bands, Disperse Yellow BROB, Disperse Red 902, and Disperse Blue 825, were used to prepare color nanoparticles. The color nanoparticles containing dye molecules were prepared by microemulsion polymerization. The structure and morphology of color composites were characterized by TEM, XRD and HAADF-STEM. The light filtering performances of PVA composites were discussed.
2.4. Preparation of color polymeric films containing the dye molecules PVA was dissolved in a certain amount of water to get 6% (w/w) PVA solution. The color nanoparticle colloid, 10 g, was added to the 6% (w/w) PVA solution, 100 g. The mixture was stirred for 30 min and placed for 24 h. The PVA mixture was coated on the glass slides. The thin films were dried at room temperature for 12 h. The color PVA films containing nanoparticles were obtained. The thickness of the composite films in the experiment was about 0.060 mm. 2.5. Characterization of nanoparticles and color PVA films
2. Experimental
Surface tension (mN/m)was measured using JK99C Automatic Surface Tensiometer, (Shanghai Zhongcheng Co. China). Zeta potential (ζ)(mV)was determined by Nano-ZS90, (Malvern Co. England). The particle size of the color polymeric nanoparticles was determined by Laser Particle Size Analyzer, LS-13320 (Beckman Coulter, Inc., Brea, USA). Fourier transform infrared spectrum (FT-IR) was measured using a Nexus-670 FT-IR Spectrometer (Nicolet Analytical Instruments, Madison, WI, USA). The morphology of the nanoparticles was observed by Field Emission Scanning Electron Microscopy (FESEM) S-4800 (HITACHI, Japan). TEM data were obtained with JEM-2100 (JEOL, Japan). The absorbance spectrum of the films was recorded at room temperature on a Hitachi U-3310 UV–Vis spectrometer (HITACHI, Japan). The X-ray powder diffraction (XRD) pattern was obtained using a D/ max-2550 PC with Cu Kα radiation (λ = 1.5406 Å) (Rigaku, Japan).
2.1. Materials
3. Results and discussion
Methyl methacrylate (MMA), butyl acrylate (BA) and polymer matrix materials, polyvinyl alcohol (PVA), were purchased from Shanghai Chemical Reagent Plant, Shanghai, China. Sodium dodecyl sulfate (SDS) and nonionic surfactant, Tween 80, were obtained from Huangma Chemical Company, Shangyu, China. MMA and BA monomers were purified by distillation under the reduced pressure before use. Three disperse dyes, Disperse Yellow BROB, Disperse Red 902, and Disperse Blue 825, were obtained from Zhejiang Wanfeng Chemical Company, Shaoxing, China. Other chemicals were from Shanghai Chemical Reagent Plant, Shanghai, China.
3.1. Preparation of color polymeric nanoparticles Azo dyes have been paid considerable attention due to their optical characteristics, such as optical data storage, spectral light filters, and nonlinear optics. Three azo dyes used in this study possess different absorbance regions. The absorption spectra of three dyes can cover the entire visible spectrum and help to regulate the absorption band. The chemical structures of the dyes are shown in Scheme 1. Disperse dye can be well dissolved in organic solvents in molecule. Monomers, MMA and BA, are good solvents for disperse dyes. The disperse dyes were firstly dissolved in the mixture solvents of MMA and BA (MMA:BA = 3:1), respectively. Then, the mixture monomers containing the dye molecules were emulsified as a microemulsion and further polymerization. The dye molecules were embedded in the nanoparticles of the polymers. The particle size distribution, surface tension, viscosity and Zeta (ζ) potential of the nanoparticle microemulsions were respectively measured and shown in Table 1. The average particle sizes of three nanoparticle microemulsions are at the range of 85–100 nm. The surface tension of three color nanoparticles microemulsions are between 42 mN/m and 48 mN/m. Zeta (ζ) potentials are around −54∼-60 mV. The viscosities are between 2.87 mPa s and 3.12 mPa s. The IR spectra of the pure copolymer MMA-BA (a), three color nanoparticles containing dyes (b,c,d), and three pure dyes (e,f,g) were recorded and shown in Fig. 1, respectively. The stretching vibration band of the C]O groups in the copolymer film appeared at 1733 cm−1. The vibration band of C]O groups at 1733 cm−1 also appeared in the three color nanoparticles. The band at 1610 cm−1 was attributed to the stretching vibration of the eC]N groups linked azo group in the three color nanoparticles and pure dyes, respectively. The azo group band
2.2. Dissolution of the dispersive dyes and preparation of microemulsion Dispersive dye, 8.5 g, was dissolved in MMA:BA mixture monomers (MMA:BA = 3:1, w/w), 27.8 g. The dye solution was a color transparent solution. Then, the emulsifiers, SDS 0.58 g, Tween 801.06 g, and isopropanol 0.5 g, were added into the dye solution. A certain amount of water was slowly dropped into the monomer solution (oil phase) at room temperature under stirring. The recipe of microemulsion (weight ratio): MMA:BA = 3:1 27.8%, dye 8.5%, SDS 0.58%, Tween-80 1.06%, isopropanol 0.5%, deionized water 61.56%. Then, the emulsion was stirred at high speed, 4500 r/m, in the emulsification machine until a homogeneous microemulsion was obtained (the oil in water, O/W). 2.3. Preparation of color polymeric nanoparticles The homogeneous microemulsion obtained was transferred into four neck flack equipped with thermometer, condenser, and stirrer. The microemulsion was heat to 80 °C under nitrogen. Then, a certain 2
Composites Science and Technology 172 (2019) 1–6
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Fig. 2. FESEM photographs of the color nanoparticles (a. the pure copolymer MMA-BA without dyes; b. the nanoparticles containing Disperse Yellow BROB; c. the nanoparticles containing Disperse Red 902; d. the nanoparticles containing Disperse Blue 825).
Scheme 1. Chemical structures of the disperse dyes.
Table 1 Particle size, surface tension, viscosity and Zeta (ζ) potential of the nanoparticle microemulsions. Samples
Disperse Yellow BROB
Disperse Red 902
Disperse Blue 825
Average particle sizes (nm) Surface tension (mN/m) Zeta potential (ζ)(mV) Viscosity (mPa.s)
85.1
99.5
95.1
47.37 −59.8 2.87
42.69 −54.8 3.12
45.45 −55.9 3.06
color nanoparticles contained three dyes, respectively. The dye molecules were polymerized into polymer nanoparticles.
3.2. Morphological structures of the color polymeric nanoparticles The surface morphologies of three color polymeric nanoparticles containing three dispersive dyes were determined by FESEM and shown in Fig. 2, respectively. They indicate that three nanoparticles containing three dispersive dyes were all homogeneous nanospheres with regular shape and size below 50–70 nm. The dye-containing nanoparticles had the same appearance and size as the pure copolymer. The TEM photographs of three color polymeric nanoparticles were also observed and shown in Fig. 3, respectively. It also indicates that the nanoparticles are neat and uniform round ball with size below 50–70 nm. The inside of the small ball is uniform and there are no aggregated solid dyes in it. Because of the small size, these nanoparticles have excellent dispersity in water. The XRD pattern of the nanoparticles containing Disperse Yellow BROB was recorded and shown in Fig. 4. The XRD pattern of Disperse Yellow BROB and the pure copolymer MMA-BA without dyes were also inserted in Fig. 4, respectively. In the XRD patterns, Fig. 4 a, c are the nanoparticles and the pure copolymer MMA-BA, respectively. They showed amorphous behavior. Fig. 4 b is the disperse dye crystal and show crystalline nature. Fig. 4 b & c as control samples are used to compare with the composite film. Disperse Yellow BROB is a stellate
Fig. 1. IR spectra of the nanoparticles containing the dispersive dyes (a. the copolymer of PAA and BA without dyes; b. the nanoparticles containing Disperse Yellow BROB; c. the nanoparticles containing Disperse Blue 825; d. the nanoparticles containing Disperse Red 902; e. pure Disperse Yellow BROB; f. pure Disperse Blue 825; g. pure Disperse Red 902).
(-N]N-) of the three dyes appeared at 1465 cm−1. The shoulders at 1364 cm−1 in three dyes observed were attributed to the stretching vibration of aromatic cycle. The peak was observed around 1150 cm−1, which were attributed to the stretching vibration of the –CN in Disperse Yellow BROB and Disperse Red 902, and the stretching vibration of the –C]N- in Disperse Blue 825, respectively. They indicate that three
Fig. 3. TEM photographs of the color polymeric nanoparticles (a. the nanoparticles containing Disperse Yellow BROB; b. the nanoparticles containing Disperse Red 902; c. the nanoparticles containing Disperse Blue 825). 3
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Fig. 4. XRD patterns of the nanoparticles containing Disperse Yellow BROB (a. the nanoparticles containing Disperse Yellow BROB; b. the pure Disperse Yellow BROB; c. the pure copolymer MMA-BA).
Fig. 5. Appearances of the color PVA films (a, the film containing Disperse Yellow BROB; b, the film containing Disperse Red 902; c. the film containing Disperse Blue 825). (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)
Fig. 7. Absorption spectra of three color films. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)
3.3. Controllable sunlight absorption of color polymeric films PVA was as polymer matrix materials of dye-doped. The certain polymeric nanoparticles were mixed in PVA solution. Then, they were made into color PVA films containing three polymer nanoparticles, respectively. The appearances of the color films were photographed by a digital camera and the pictures were shown in Fig. 5. It indicates that three PVA polymeric films obtained are very beautiful, color, and uniform. The SEM photographs of pure PVA film and three color films were also observed and shown in Fig. 6, respectively. It indicates that the pure PVA film is uniform and smoothing. There are a large number of colored lattices in the color films, which are the nanoparticles with regular lattice arrays containing dye molecules. The absorption spectra of three color films were measured and shown in Fig. 7. It indicates that three color films possess different absorption bands in visible light region. The maximum absorption peaks (λmax) are 423 nm for the orange film, 521 nm for the red film and 594 nm for the blue film, respectively. They are assigned to the ππ* transition of the conjugated system of doped-dyes. The light that is
Fig. 6. SEM photographs of the films (a. PVA film; b, orange film; c, red film; d. blue film).
crystal like organic pigments [29]. The observed well-defined Bragg's peaks at specific 2θ angles, 5.8°, 10.5°, 12.3°, 16.8°, 21.1°, 24.2°, 26.3° and 30.2°, also indicate that the dye is highly crystalline. However, the XRD pattern (4 a) indicates that the nanoparticles did not show the presence of BROB crystals. The results indicate that the dyes are evenly dispersed in colloidal nano-particles in molecules. This will be very beneficial for the absorption of specific wavelengths of sunlight.
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the thermal decomposition temperature is over 200 °C. The polymer matrix material can also be changed according to requirements. It can also be assembled or deposited on other substrates including glass, plastics and so on. Even they can be spray on the plant leaves or fruit surfaces to form films to obtain selective sunlight filtering. They can cost-effectively deliver the light with the desirable wavelengths to the large scale cultivation or environment systems. So, the controlled absorption film filters have potential applications in many fields, such as agriculture, environmental, biotechnology and the military field as a signal light with a specific spectrum [30–32]. 4. Conclusion Dye-doped nano-polymeric composites of the controllable sunlight absorption were prepared. Three nanoparticles doped the dispersive dyes were all homogeneous round balls with the size below 50–70 nm. Three PVA polymeric composites containing nanoparticles are very beautiful and uniform. They are composed of a large number of nanoparticles with regular lattice arrays containing dye molecules. The composites possess different absorption bands in the visible light region. The color films with tunable sunlight absorption based on the three color nanoparticles can be designed and assembled to selectively transmit specific sunlight from sun. The composites containing nanoparticles are convenient, flexible, and cost-effective. The controlled sunlight absorption films have potential applications in energy, agriculture, environment and biotechnology.
Fig. 8. Different absorption bands of the films designed by adjusting the recipe (The appearances of the color films, a: orange:red 1:1; b: orange:blue 1:8; c: red:blue 1:8). (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)
Acknowledgements This work was financially supported by the Shanghai Natural Science Foundation (Grant No. 18ZR1400800) and the Fundamental Research Funds for the Central Universities (CUSF-DH-D-2018062). References [1] M.C. Gupta, C. Ungaro, J.J. Foley, S.K. Gray, Optical nanostructures design, fabrication, and applications for solar/thermal energy conversion, Sol. Energy 165 (2018) 100–114. [2] G. Fredi, A. Dorigato, L. Fambri, A. Pegoretti, Multifunctional epoxy/carbon fiber laminates for thermal energy storage and release, Compos. Sci. Technol. 158 (2018) 101–111. [3] C. Gao, G. Chen, Conducting polymer/carbon particle thermoelectric composites: emerging green energy materials, Compos. Sci. Technol. 124 (2016) 52–70. [4] Q. Tang, H. Zhang, B. He, P. Yang, An all-weather solar cell that can harvest energy from sunlight and rain, Nano Energy 30 (2016) 818–824. [5] A. Elsheikh, S. Sharshir, M.E. Mostafa, F. Essa, M.K.A. Ali, Applications of nanofluids in solar energy: a review of recent advances, Renew. Sustain. Energy Rev. 82 (2018) 3483–3502. [6] N.R. Alluri, S. Selvarajan, A. Chandrasekhar, B. Saravanakumar, J.H. Jeong, S.J. Kim, Piezoelectric BaTiO3/alginate spherical composite beads for energy harvesting and self-powered wearable flexion sensor, Compos. Sci. Technol. 142 (2017) 65–78. [7] Y. Liu, D. Zhang, The preparation of reduced graphene oxide-TiO2 composite materials towards transparent, strain sensing and photodegradation multifunctional films, Compos. Sci. Technol. 137 (2016) 102–108. [8] C.L. Kim, J.J. Lee, Y.J. Oh, D.E. Kim, Smart wearable heaters with high durability, flexibility, water-repellent and shape memory characteristics, Compos. Sci. Technol. 152 (2017) 173–180. [9] J. Choi, H. Shin, M. Cho, Multiscale multiphysical analysis of photo-mechanical properties of interphase in light-responsive polymer nanocomposites, Compos. Sci. Technol. 160 (2018) 32–41. [10] C. Michael, M. del Ninno, M. Gross, Z. Wen, Use of wavelength-selective optical light filters for enhanced microalgal growth in different algal cultivation systems, Bioresour. Technol. 179 (2015) 473–482. [11] M. Gao, Y. Qi, W. Song, H. Xu, Effects of di-n-butyl phthalate and di (2-ethylhexyl) phthalate on the growth, photosynthesis, and chlorophyll fluorescence of wheat seedlings, Chemosphere 151 (2016) 76–83. [12] C. Jiang, M. Johkan, M. Hohjo, S. Tsukagoshi, M. Ebihara, A. Nakaminami, T. Maruo, Photosynthesis, plant growth, and fruit production of single-truss tomato improves with supplemental lighting provided from underneath or within the inner canopy, Sci. Hortic. 222 (2017) 221–229. [13] Y. Miao, Z. Zhu, Q. Guo, H. Ma, L. Zhu, Alternate wetting and drying irrigationmediated changes in the growth, photosynthesis and yield of the medicinal plant Tulipa edulis, Ind. Crop. Prod. 66 (2015) 81–88. [14] A. Martirosyan, Optical properties of light filter designed on absorbing axicon, Opt.
Fig. 9. Different absorption bands of the designed films.
not absorbed can transmit the color film. This creates a membrane filter. Based on the three color nanoparticles, the films of different absorption bands can be designed by adjusting the recipe in principle. One of the most interesting features of dye-doped polymer films is the controllable change of the absorption spectral regions by mixing different color nanoparticles. Take for example, the films of different absorption bands designed by adjusting the recipes can be obtained and their visible absorption spectra are shown in Fig. 8. The photographs of the color films are also inserted in Fig. 8. The light absorption bands of the films by other group recipes are shown in Fig. 9. Thus the tunable sunlight absorption of the films can be realized by mixed different color nanoparticles. Because the dye molecules can be stabilized in the nanoparticles, the films with accurate absorption band can be obtained by adjusting the recipes. A controlled absorption film filter using three dye-doped nanoparticles can be assembled to selectively transmit specific wavelengths from natural sunlight. The materials can be tuned to provide different visible spectra allowing certain bands to be more prominent than others. Since the composite is mainly used at room temperature, the thermal stability is good. The used dyes have good thermal stability and 5
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a D–π–A system, Color. Technol. 131 (2015) 38–42. [24] E. Baez, N. Quazi, I. Ivanov, S.N. Bhattacharya, Stability study of nanopigment dispersions, Adv. Powder Technol. 20 (2009) 267–272. [25] M.A. Inam, S. Ouattara, C. Frances, Effects of concentration of dispersions on particle sizing during production of fine particles in wet grinding process, Powder Technol. 208 (2011) 329–336. [26] M. Sundhoro, J. Park, K.W. Jayawardana, X. Chen, H.S.N. Jayawardena, M. Yan, Poly (HEMA-co-HEMA-PFPA): synthesis and preparation of stable micelles encapsulating imaging nanoparticles, J. Colloid Interface Sci. 500 (2017) 1–8. [27] F. Kemper, E. Beckert, R. Eberhardt, A. Tünnermann, Novel solution-processable light filter approaches for light detection purpose in lab-on-chip-systems, Mater. Today 4 (2017) 5023–5029. [28] P.D. Christofides, M. Li, L. Mädler, Control of particulate processes: recent results and future challenges, Powder Technol. 175 (2007) 1–7. [29] M. Li, K. Song, K. Xie, A. Hou, Dispersion of Disperse Yellow BROB with polymer surfactants and its dyeing property for polyester fabric, Fibers Polym. 16 (2015) 614–620. [30] P. Sanmartín, D. Vázquez-Nion, J. Arines, L. Cabo-Domínguez, B. Prieto, Controlling growth and colour of phototrophs by using simple and inexpensive coloured lighting: a preliminary study in the Light4 Heritage project towards future strategies for outdoor illumination, Int. Biodeterior. Biodegrad. 122 (2017) 107–115. [31] J.M. Nam, J.H. Kim, J.G. Kim, Effects of light intensity and plant density on growth and reproduction of the amphicarpic annual Persicaria thunbergii, Aquat. Bot. 142 (2017) 119–122. [32] C. Wu, T.W. Kim, T. Guo, F. Li, Wearable ultra-lightweight solar textiles based on transparent electronic fabrics, Nano Energy 32 (2017) 367–373.
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Contents lists available at ScienceDirect
Composites Science and Technology journal homepage: www.elsevier.com/locate/compscitech
Controllable wavelength-selective optical composite based on nanopolymeric films with doped dyes
T
Aiqin Gaoa, Danna Fua, Aiqin Houb, Kongliang Xiea,∗ a b
College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, PR China National Engineering Research Center for Dyeing and Finishing of Textiles, Donghua University, Shanghai, 201620, PR China
A R T I C LE I N FO
A B S T R A C T
Keywords: Polymeric nanoparticles Controllable light absorption Solar energy Dye-doped Selectively transmittance
The novel color optical composites with controllable light absorption from the solar energy based on polyvinyl alcohol (PVA) as matrix materials were investigated. The nanoparticles with molecular level dye-doped were prepared by microemulsion polymerization. The structure and morphology of the nanoparticles and the color nano-films were characterized by Fourier transform infrared spectrum (FT-IR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray powder diffraction (XRD) analysis. Three nanoparticles with dye-doped are all homogeneous nanospheres with regular shape and size of 50–70 nm. Three PVA color films containing nanoparticles possess different absorption bands in the visible light region. A controlled sunlight absorption film filter using dye-doped nanoparticles can be arbitrarily designed and assembled by adjusting the recipe to selectively transmit specific wavelengths from sunlight. Because the dye molecules are stabilized in the nanoparticles, the absorption band of the membranes can be precisely controlled. It can be conveniently assembled or deposited on other substrates to form nano-membranes. The composite containing color nanoparticles is simple, flexible, and cost-effective. They have potential applications in many fields, such as energy, agriculture, environment and biotechnology.
1. Introduction Solar energy has always been the most promising renewable energy. In recent years, how to make full use of solar energy has become an important research field [1–3]. The researches for the acceptance and conversion of solar energy based on nano-composites are being increased owe to their widely applications [4–6]. The selecting absorption sunlight composites based on the polymer matrix have been widely paid attention in the energy, agriculture, environment, biotechnology, medical diagnosis, food, and other high-technology fields, which are demonstrated to be crucially important tools in many novel applications [7–9]. For example, microalgae are a group of photosynthetic organisms, which can rapidly grow under certain light wavelengths from the selecting sunlight spectra. The wavelength of the light source also plays an important role in the algal culture. According to the experience of agriculture and marine farming, each plant or microalgae need a specific wavelength of light to grow. The certain spectrum can be regulated according to the sensitivity of the plants to light. The nanocomposites, which can select transmit certain wavelength light from natural sunlight, significantly improve biomass yield [10,11]. Most often natural sunlight is not optimized for some plant cell growth due to
∗
the wide light spectra including ultra-violet (UV) and infrared red (IR) rays, which can damage the cellular structure. The efficiency of photosynthesis can be improved by the selecting absorption of spectral light [12,13]. There are very important applications in agriculture, ocean, environment, and biotechnology, especially the ones requiring the processing on large areas with costs. The optical devices based on doped polymer matrix are gaining attention and potentially applied in laser, medical imaging, photonic devices, spectral light filters [14–16]. The doped polymer membranes with special optical properties have become a hot research field. Some dopants, such as semiconducting or metal nanoparticles, and dyes can directly influence the optical properties of the polymer films. The spectral light filters can be designed by using various polymer materials and various chromophores. The advantages of polymer-based molecular systems are their low cost and easily modified to match the specific needs. However, the composite films with dopants have their disadvantages, such as transmission band is not easy to arbitrarily design and regulate, especially in the visible band [17–19]. Among these novel materials, dye-doped polymer thin films are expected as candidates of cost-effective, simple and cheap fabrication technologies. Of course, polymeric matrix would restrict the activity to optical sources.
Corresponding author. E-mail address: [email protected] (K. Xie).
https://doi.org/10.1016/j.compscitech.2019.01.001 Received 18 July 2018; Received in revised form 30 December 2018; Accepted 1 January 2019 Available online 04 January 2019 0266-3538/ © 2019 Elsevier Ltd. All rights reserved.
Composites Science and Technology 172 (2019) 1–6
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amount of the initiator, ammonium persulphate, 0.15%, was slowly dropped into the microemulsion. The polymerized reaction was carried out for 4 h at 85 °C. The color polymeric nanoparticle colloid was obtained.
So, the matrix materials should be transparent, non-absorption light and cheap. Dye-doped polymer composites can generate designing absorption in the specific spectral regions or emission on the whole visible spectral region [20–22]. Among all kinds of dyes, disperse dyes, similar with organic pigments, are almost insoluble in water, which are the crystals precipitated from water or other organic solvent [23,24]. However, it is difficult to shatter and disperse into molecules in the polymer films. The milling method represents one of the most popular approaches to produce the required powder particles by means of wet grinding process. Due to the hydrophobic character and high surface energy of the dye particles, they tend to aggregate into bigger particles [25,26]. It is important to investigate nano-dispersive technology or prepare molecule-sized particles to prevent the agglomeration of the disperse dyes. Nanomaterials and nano-dispersive technology have become a research hotspot in the advanced materials, colloid and interface fields. Several methods have been reported for the nano-dispersive dyes, such as dispersion, emulsion, and miniemulsion polymerization [27,28]. However, most dyes exist in these systems with dye aggregates, which can further affect the selective absorption property of solar spectrum. We note that the disperse dyes are insoluble in water, but they can dissolve in organic monomer of polymer in molecules. In this paper, the mixture monomers of methyl methacrylate (MMA) and butyl acrylate (BA) as organic solvent were used to dissolve the dyes, then nano-emulsify. Three dispersive dyes with different absorption bands, Disperse Yellow BROB, Disperse Red 902, and Disperse Blue 825, were used to prepare color nanoparticles. The color nanoparticles containing dye molecules were prepared by microemulsion polymerization. The structure and morphology of color composites were characterized by TEM, XRD and HAADF-STEM. The light filtering performances of PVA composites were discussed.
2.4. Preparation of color polymeric films containing the dye molecules PVA was dissolved in a certain amount of water to get 6% (w/w) PVA solution. The color nanoparticle colloid, 10 g, was added to the 6% (w/w) PVA solution, 100 g. The mixture was stirred for 30 min and placed for 24 h. The PVA mixture was coated on the glass slides. The thin films were dried at room temperature for 12 h. The color PVA films containing nanoparticles were obtained. The thickness of the composite films in the experiment was about 0.060 mm. 2.5. Characterization of nanoparticles and color PVA films
2. Experimental
Surface tension (mN/m)was measured using JK99C Automatic Surface Tensiometer, (Shanghai Zhongcheng Co. China). Zeta potential (ζ)(mV)was determined by Nano-ZS90, (Malvern Co. England). The particle size of the color polymeric nanoparticles was determined by Laser Particle Size Analyzer, LS-13320 (Beckman Coulter, Inc., Brea, USA). Fourier transform infrared spectrum (FT-IR) was measured using a Nexus-670 FT-IR Spectrometer (Nicolet Analytical Instruments, Madison, WI, USA). The morphology of the nanoparticles was observed by Field Emission Scanning Electron Microscopy (FESEM) S-4800 (HITACHI, Japan). TEM data were obtained with JEM-2100 (JEOL, Japan). The absorbance spectrum of the films was recorded at room temperature on a Hitachi U-3310 UV–Vis spectrometer (HITACHI, Japan). The X-ray powder diffraction (XRD) pattern was obtained using a D/ max-2550 PC with Cu Kα radiation (λ = 1.5406 Å) (Rigaku, Japan).
2.1. Materials
3. Results and discussion
Methyl methacrylate (MMA), butyl acrylate (BA) and polymer matrix materials, polyvinyl alcohol (PVA), were purchased from Shanghai Chemical Reagent Plant, Shanghai, China. Sodium dodecyl sulfate (SDS) and nonionic surfactant, Tween 80, were obtained from Huangma Chemical Company, Shangyu, China. MMA and BA monomers were purified by distillation under the reduced pressure before use. Three disperse dyes, Disperse Yellow BROB, Disperse Red 902, and Disperse Blue 825, were obtained from Zhejiang Wanfeng Chemical Company, Shaoxing, China. Other chemicals were from Shanghai Chemical Reagent Plant, Shanghai, China.
3.1. Preparation of color polymeric nanoparticles Azo dyes have been paid considerable attention due to their optical characteristics, such as optical data storage, spectral light filters, and nonlinear optics. Three azo dyes used in this study possess different absorbance regions. The absorption spectra of three dyes can cover the entire visible spectrum and help to regulate the absorption band. The chemical structures of the dyes are shown in Scheme 1. Disperse dye can be well dissolved in organic solvents in molecule. Monomers, MMA and BA, are good solvents for disperse dyes. The disperse dyes were firstly dissolved in the mixture solvents of MMA and BA (MMA:BA = 3:1), respectively. Then, the mixture monomers containing the dye molecules were emulsified as a microemulsion and further polymerization. The dye molecules were embedded in the nanoparticles of the polymers. The particle size distribution, surface tension, viscosity and Zeta (ζ) potential of the nanoparticle microemulsions were respectively measured and shown in Table 1. The average particle sizes of three nanoparticle microemulsions are at the range of 85–100 nm. The surface tension of three color nanoparticles microemulsions are between 42 mN/m and 48 mN/m. Zeta (ζ) potentials are around −54∼-60 mV. The viscosities are between 2.87 mPa s and 3.12 mPa s. The IR spectra of the pure copolymer MMA-BA (a), three color nanoparticles containing dyes (b,c,d), and three pure dyes (e,f,g) were recorded and shown in Fig. 1, respectively. The stretching vibration band of the C]O groups in the copolymer film appeared at 1733 cm−1. The vibration band of C]O groups at 1733 cm−1 also appeared in the three color nanoparticles. The band at 1610 cm−1 was attributed to the stretching vibration of the eC]N groups linked azo group in the three color nanoparticles and pure dyes, respectively. The azo group band
2.2. Dissolution of the dispersive dyes and preparation of microemulsion Dispersive dye, 8.5 g, was dissolved in MMA:BA mixture monomers (MMA:BA = 3:1, w/w), 27.8 g. The dye solution was a color transparent solution. Then, the emulsifiers, SDS 0.58 g, Tween 801.06 g, and isopropanol 0.5 g, were added into the dye solution. A certain amount of water was slowly dropped into the monomer solution (oil phase) at room temperature under stirring. The recipe of microemulsion (weight ratio): MMA:BA = 3:1 27.8%, dye 8.5%, SDS 0.58%, Tween-80 1.06%, isopropanol 0.5%, deionized water 61.56%. Then, the emulsion was stirred at high speed, 4500 r/m, in the emulsification machine until a homogeneous microemulsion was obtained (the oil in water, O/W). 2.3. Preparation of color polymeric nanoparticles The homogeneous microemulsion obtained was transferred into four neck flack equipped with thermometer, condenser, and stirrer. The microemulsion was heat to 80 °C under nitrogen. Then, a certain 2
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Fig. 2. FESEM photographs of the color nanoparticles (a. the pure copolymer MMA-BA without dyes; b. the nanoparticles containing Disperse Yellow BROB; c. the nanoparticles containing Disperse Red 902; d. the nanoparticles containing Disperse Blue 825).
Scheme 1. Chemical structures of the disperse dyes.
Table 1 Particle size, surface tension, viscosity and Zeta (ζ) potential of the nanoparticle microemulsions. Samples
Disperse Yellow BROB
Disperse Red 902
Disperse Blue 825
Average particle sizes (nm) Surface tension (mN/m) Zeta potential (ζ)(mV) Viscosity (mPa.s)
85.1
99.5
95.1
47.37 −59.8 2.87
42.69 −54.8 3.12
45.45 −55.9 3.06
color nanoparticles contained three dyes, respectively. The dye molecules were polymerized into polymer nanoparticles.
3.2. Morphological structures of the color polymeric nanoparticles The surface morphologies of three color polymeric nanoparticles containing three dispersive dyes were determined by FESEM and shown in Fig. 2, respectively. They indicate that three nanoparticles containing three dispersive dyes were all homogeneous nanospheres with regular shape and size below 50–70 nm. The dye-containing nanoparticles had the same appearance and size as the pure copolymer. The TEM photographs of three color polymeric nanoparticles were also observed and shown in Fig. 3, respectively. It also indicates that the nanoparticles are neat and uniform round ball with size below 50–70 nm. The inside of the small ball is uniform and there are no aggregated solid dyes in it. Because of the small size, these nanoparticles have excellent dispersity in water. The XRD pattern of the nanoparticles containing Disperse Yellow BROB was recorded and shown in Fig. 4. The XRD pattern of Disperse Yellow BROB and the pure copolymer MMA-BA without dyes were also inserted in Fig. 4, respectively. In the XRD patterns, Fig. 4 a, c are the nanoparticles and the pure copolymer MMA-BA, respectively. They showed amorphous behavior. Fig. 4 b is the disperse dye crystal and show crystalline nature. Fig. 4 b & c as control samples are used to compare with the composite film. Disperse Yellow BROB is a stellate
Fig. 1. IR spectra of the nanoparticles containing the dispersive dyes (a. the copolymer of PAA and BA without dyes; b. the nanoparticles containing Disperse Yellow BROB; c. the nanoparticles containing Disperse Blue 825; d. the nanoparticles containing Disperse Red 902; e. pure Disperse Yellow BROB; f. pure Disperse Blue 825; g. pure Disperse Red 902).
(-N]N-) of the three dyes appeared at 1465 cm−1. The shoulders at 1364 cm−1 in three dyes observed were attributed to the stretching vibration of aromatic cycle. The peak was observed around 1150 cm−1, which were attributed to the stretching vibration of the –CN in Disperse Yellow BROB and Disperse Red 902, and the stretching vibration of the –C]N- in Disperse Blue 825, respectively. They indicate that three
Fig. 3. TEM photographs of the color polymeric nanoparticles (a. the nanoparticles containing Disperse Yellow BROB; b. the nanoparticles containing Disperse Red 902; c. the nanoparticles containing Disperse Blue 825). 3
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Fig. 4. XRD patterns of the nanoparticles containing Disperse Yellow BROB (a. the nanoparticles containing Disperse Yellow BROB; b. the pure Disperse Yellow BROB; c. the pure copolymer MMA-BA).
Fig. 5. Appearances of the color PVA films (a, the film containing Disperse Yellow BROB; b, the film containing Disperse Red 902; c. the film containing Disperse Blue 825). (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)
Fig. 7. Absorption spectra of three color films. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)
3.3. Controllable sunlight absorption of color polymeric films PVA was as polymer matrix materials of dye-doped. The certain polymeric nanoparticles were mixed in PVA solution. Then, they were made into color PVA films containing three polymer nanoparticles, respectively. The appearances of the color films were photographed by a digital camera and the pictures were shown in Fig. 5. It indicates that three PVA polymeric films obtained are very beautiful, color, and uniform. The SEM photographs of pure PVA film and three color films were also observed and shown in Fig. 6, respectively. It indicates that the pure PVA film is uniform and smoothing. There are a large number of colored lattices in the color films, which are the nanoparticles with regular lattice arrays containing dye molecules. The absorption spectra of three color films were measured and shown in Fig. 7. It indicates that three color films possess different absorption bands in visible light region. The maximum absorption peaks (λmax) are 423 nm for the orange film, 521 nm for the red film and 594 nm for the blue film, respectively. They are assigned to the ππ* transition of the conjugated system of doped-dyes. The light that is
Fig. 6. SEM photographs of the films (a. PVA film; b, orange film; c, red film; d. blue film).
crystal like organic pigments [29]. The observed well-defined Bragg's peaks at specific 2θ angles, 5.8°, 10.5°, 12.3°, 16.8°, 21.1°, 24.2°, 26.3° and 30.2°, also indicate that the dye is highly crystalline. However, the XRD pattern (4 a) indicates that the nanoparticles did not show the presence of BROB crystals. The results indicate that the dyes are evenly dispersed in colloidal nano-particles in molecules. This will be very beneficial for the absorption of specific wavelengths of sunlight.
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the thermal decomposition temperature is over 200 °C. The polymer matrix material can also be changed according to requirements. It can also be assembled or deposited on other substrates including glass, plastics and so on. Even they can be spray on the plant leaves or fruit surfaces to form films to obtain selective sunlight filtering. They can cost-effectively deliver the light with the desirable wavelengths to the large scale cultivation or environment systems. So, the controlled absorption film filters have potential applications in many fields, such as agriculture, environmental, biotechnology and the military field as a signal light with a specific spectrum [30–32]. 4. Conclusion Dye-doped nano-polymeric composites of the controllable sunlight absorption were prepared. Three nanoparticles doped the dispersive dyes were all homogeneous round balls with the size below 50–70 nm. Three PVA polymeric composites containing nanoparticles are very beautiful and uniform. They are composed of a large number of nanoparticles with regular lattice arrays containing dye molecules. The composites possess different absorption bands in the visible light region. The color films with tunable sunlight absorption based on the three color nanoparticles can be designed and assembled to selectively transmit specific sunlight from sun. The composites containing nanoparticles are convenient, flexible, and cost-effective. The controlled sunlight absorption films have potential applications in energy, agriculture, environment and biotechnology.
Fig. 8. Different absorption bands of the films designed by adjusting the recipe (The appearances of the color films, a: orange:red 1:1; b: orange:blue 1:8; c: red:blue 1:8). (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)
Acknowledgements This work was financially supported by the Shanghai Natural Science Foundation (Grant No. 18ZR1400800) and the Fundamental Research Funds for the Central Universities (CUSF-DH-D-2018062). References [1] M.C. Gupta, C. Ungaro, J.J. Foley, S.K. Gray, Optical nanostructures design, fabrication, and applications for solar/thermal energy conversion, Sol. Energy 165 (2018) 100–114. [2] G. Fredi, A. Dorigato, L. Fambri, A. Pegoretti, Multifunctional epoxy/carbon fiber laminates for thermal energy storage and release, Compos. Sci. Technol. 158 (2018) 101–111. [3] C. Gao, G. Chen, Conducting polymer/carbon particle thermoelectric composites: emerging green energy materials, Compos. Sci. Technol. 124 (2016) 52–70. [4] Q. Tang, H. Zhang, B. He, P. Yang, An all-weather solar cell that can harvest energy from sunlight and rain, Nano Energy 30 (2016) 818–824. [5] A. Elsheikh, S. Sharshir, M.E. Mostafa, F. Essa, M.K.A. Ali, Applications of nanofluids in solar energy: a review of recent advances, Renew. Sustain. Energy Rev. 82 (2018) 3483–3502. [6] N.R. Alluri, S. Selvarajan, A. Chandrasekhar, B. Saravanakumar, J.H. Jeong, S.J. Kim, Piezoelectric BaTiO3/alginate spherical composite beads for energy harvesting and self-powered wearable flexion sensor, Compos. Sci. Technol. 142 (2017) 65–78. [7] Y. Liu, D. Zhang, The preparation of reduced graphene oxide-TiO2 composite materials towards transparent, strain sensing and photodegradation multifunctional films, Compos. Sci. Technol. 137 (2016) 102–108. [8] C.L. Kim, J.J. Lee, Y.J. Oh, D.E. Kim, Smart wearable heaters with high durability, flexibility, water-repellent and shape memory characteristics, Compos. Sci. Technol. 152 (2017) 173–180. [9] J. Choi, H. Shin, M. Cho, Multiscale multiphysical analysis of photo-mechanical properties of interphase in light-responsive polymer nanocomposites, Compos. Sci. Technol. 160 (2018) 32–41. [10] C. Michael, M. del Ninno, M. Gross, Z. Wen, Use of wavelength-selective optical light filters for enhanced microalgal growth in different algal cultivation systems, Bioresour. Technol. 179 (2015) 473–482. [11] M. Gao, Y. Qi, W. Song, H. Xu, Effects of di-n-butyl phthalate and di (2-ethylhexyl) phthalate on the growth, photosynthesis, and chlorophyll fluorescence of wheat seedlings, Chemosphere 151 (2016) 76–83. [12] C. Jiang, M. Johkan, M. Hohjo, S. Tsukagoshi, M. Ebihara, A. Nakaminami, T. Maruo, Photosynthesis, plant growth, and fruit production of single-truss tomato improves with supplemental lighting provided from underneath or within the inner canopy, Sci. Hortic. 222 (2017) 221–229. [13] Y. Miao, Z. Zhu, Q. Guo, H. Ma, L. Zhu, Alternate wetting and drying irrigationmediated changes in the growth, photosynthesis and yield of the medicinal plant Tulipa edulis, Ind. Crop. Prod. 66 (2015) 81–88. [14] A. Martirosyan, Optical properties of light filter designed on absorbing axicon, Opt.
Fig. 9. Different absorption bands of the designed films.
not absorbed can transmit the color film. This creates a membrane filter. Based on the three color nanoparticles, the films of different absorption bands can be designed by adjusting the recipe in principle. One of the most interesting features of dye-doped polymer films is the controllable change of the absorption spectral regions by mixing different color nanoparticles. Take for example, the films of different absorption bands designed by adjusting the recipes can be obtained and their visible absorption spectra are shown in Fig. 8. The photographs of the color films are also inserted in Fig. 8. The light absorption bands of the films by other group recipes are shown in Fig. 9. Thus the tunable sunlight absorption of the films can be realized by mixed different color nanoparticles. Because the dye molecules can be stabilized in the nanoparticles, the films with accurate absorption band can be obtained by adjusting the recipes. A controlled absorption film filter using three dye-doped nanoparticles can be assembled to selectively transmit specific wavelengths from natural sunlight. The materials can be tuned to provide different visible spectra allowing certain bands to be more prominent than others. Since the composite is mainly used at room temperature, the thermal stability is good. The used dyes have good thermal stability and 5
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