- Email: [email protected]
Anti-fogging behavior of water-absorbing polymer films derived from isosorbide-based epoxy resin
Author’s Accepted Manuscript Anti-fogging behavior of water-absorbing polymer films derived from isosorbide-based epoxy resin Sungjune Park, Sujin Park, Dong Hwan Jang, Hye Seung Lee, Chan Ho Park www.elsevier.com
PII: DOI: Reference:
S0167-577X(16)30880-1 http://dx.doi.org/10.1016/j.matlet.2016.05.114 MLBLUE20925
To appear in: Materials Letters Received date: 15 April 2016 Revised date: 21 May 2016 Accepted date: 25 May 2016 Cite this article as: Sungjune Park, Sujin Park, Dong Hwan Jang, Hye Seung Lee and Chan Ho Park, Anti-fogging behavior of water-absorbing polymer films derived from isosorbide-based epoxy resin, Materials Letters, http://dx.doi.org/10.1016/j.matlet.2016.05.114 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Anti-fogging behavior of water-absorbing polymer films derived from isosorbide-based epoxy resin Sungjune Park1*, Sujin Park1,2, Dong Hwan Jang1, Hye Seung Lee3, Chan Ho Park3 1
Advanced Functional Materials Research Team, Automotive Research & Development Division, Hyundai Motor Group, 18280, Republic of Korea 2 School of Chemical Engineering, Sungkyunkwan University, Suwon 440-746, Republic of Korea 3 Advanced Materials Development Team, Research & Development Center, Kukdo Chemical, 08588, Republic of Korea *
Corresponding author. E-mail address: [email protected] (S.Park).
Abstract Anti-fogging films derived from isosorbide-based epoxy polymer were fabricated by film formation and subsequent thermal polymerization. The film surfaces were characterized by scanning electron microscopy, and water contact angle and diffuse reflective ratio measurements. The anti-fogging capability was evaluated by in situ monitoring of optical changes, and was controlled by varying the film thickness.
Keywords: Anti-fogging films, Water-absorbing polymer, Isosorbide epoxy resin.
1. Introduction The fogging phenomenon is generated by small water droplets condensing on the surface of an object, when the temperature of that surface is lower than that of the dew point surrounding it. As a result, light is scattered by condensed water droplets, and the surface becomes a haze.1-4 This fogging behavior limits technological applications requiring a high optical transmittance such as solar cells5 and analytical instruments such as infrared microscopes6, due to loss of function. In particular, in the case of
-1-
vehicles, fogging is often generated on the surface of the windshield due to the difference between interior- and exterior temperatures, which disturbs the drivers’ view and compromises safety. A range of surface treatment techniques to generate anti-fogging performance have therefore been developed. For instance, water droplets are barely formed and are quickly spread out on superhydrophilic surfaces (a water contact angle of 10° or less) produced by creating a geometric surface structure.7-12 Consequently, a thin water film is formed to reduce the light scattering induced by condensed water droplets. However, small structures on a micro/nanometer scale are fabricated by expensive and complicated lithographic techniques, and it is difficult to maintain shapes when pressure and abrasion from the outside are applied to the surfaces. Another well-known approach to the creation of superhydrophilic surfaces is a photochemical method using TiO2, however the surface properties are exhibited only when exposed to UV light.13-15 Here, we report a facile approach for the creation of robust anti-fogging films derived from isosorbide-based epoxy resin. The layer is fabricated by film formation and subsequent thermal polymerization. Further, the water-absorption performance (antifogging capability), which depended on film thicknesses, and the in situ measurement of the optical properties affected by the fogging phenomenon, are discussed in detail.
2. Experimental Isosorbide epoxy resin (KBM-1040, Kukdo chemical) was used to prepare the waterabsorbing polymer thin films. A 50 wt% propylene glycol mono methyl ether (PGMEA, Hannong chemical) solution was prepared, with the addition of a silane coupling agent (3-glycidoxypropylmethyldiethoxysilane) (KBM-403, Shin-etsu chemical) at 23.77 wt%
-2-
of the isosorbide epoxy resin weight to improve adhesion of the polymer to the substrate. The mixture was stirred for 1 h at 25°C. To increase thermal sensitivity, 39.8 wt% polyoxypropylenetriamine (Jeffamin T-403, Huntsman), 0.5 wt% 2-methyl imidazole (BASF), and 2.0 wt% benzyldimethylamine (Kukdo chemical) were subsequently added to the previously-formulated solution. The mixture was stirred again for 1 h at 25°C. Thin films on planar glass substrates were prepared by spin-coating in the range of 100-1000 rpm to produce polymer films with thicknesses in the range of 30-105 µm. Thermal curing was applied at 65 and 100°C for 1 h, in order to solidify the polymer films. Prior to use, the glass substrates were cleaned in ethanol and treated with ultrasonication. The cross-sectional views and thicknesses of the isosorbide epoxy polymer films were investigated using scanning force microscopy (Quanta 450, FEI). The anti-fogging capabilities of the films were evaluated by laying the films on top of a beaker containing water at 50°C. The anti-fogging performance on a cold surface was also evaluated following cooling for 30 min and removal from a refrigerator at 4°C. To investigate the mechanical strength of the polymer films, the samples were scratched 500 times by rubber with a 500 g load, and subsequently characterized by the anti-fogging test. A spectrophotometer (CM-700d, Konica Minolta) was used to characterize the optical properties. Surface wettability was characterized by water contact angle measurement after dropping a water droplet of 1 μl in volume.
3. Results and Discussion
-3-
In previous studies, isosorbide-based epoxy polymer has been recognized as a candidate material for application in the pharmaceutical and cosmetic industries, as well as a building block for polymers such as polyesters, polyethers, and polycarbonates, due to its bioderived and biodegradable properties.16-17 In particular, the water-absorption behavior in isosorbide epoxy resin is presumably linked to the network structures. For instance, the presence of OH- groups in the resin structure, since a higher hydroxyl concentration has been reported.18-20 As seen in Fig. 1, isosorbide is composed of two fused tetrahydrofuran (THF) rings with two non-equivalent hydroxyl groups21 that give the high water-absorption behavior, thus, isosorbide-based epoxy resin was used for fabrication of the anti-fogging layer in the present work.
Fig. 1. Polymeric structure of isosorbide-based epoxy resin.
Fig. 2 presents the cross-sectional views (a) and film thicknesses (b) of the thermallycured isosorbide-based epoxy polymer coated on a glass substrate. The lines along the vertical axis indicate that the majority of epoxies are well crosslinked and solidified using an amine-based curing agent by thermal treatment (Fig. 2a).22 The film thicknesses are in the range of 30-105 µm, depending on the rotation speed, however, a minimum thickness of 30 µm is limited at speeds higher than 900 rpm, due to the relatively high viscosity and strong adhesion of the epoxy materials (Fig. 2b). As shown
-4-
in Fig. 2c, the surface of the coated layer exhibits a hydrophilic state with a contact angle of 68°, which is comparable to previously reported epoxy layers.23
Fig. 2. (a) Cross-sectional SEM image of a spin-coated and thermally-cured polymer film. (b) Film thicknesses of spin-coated (at various spin speeds (rpm)) and thermally-cured polymer films. (c) Optical image of a water droplet on the polymer film. All films were thermally cured at 60 and 100°C for 1 h.
To demonstrate the anti-fogging efficiency of the polymer films, the samples were exposed to a highly humid environment. While a hazy surface is shown on the bare glass substrate due to the strong scattering of light at the curved surfaces of semispherical droplets (Fig. 3a), the isosorbide epoxy polymer film shows high clarity, and the underlying image is clearly visible though the coated surface (Fig. 3b). Crosslinkable blended systems derived from epoxy polymer have been studied in recent decades due to their favorable characteristics such as strong tensile properties.24 Fig. 3(c) shows the anti-fogging performance of the films under the same conditions following the wear resistance test. These results demonstrate the robustness of the films, since the polymer film shows excellent anti-fogging performance following the durability test. As
-5-
seen in Fig. 3(d), the underlying image is also clearly seen through the polymer films coated on both side of the substrate following cooling and removal from the refrigerator, indicating that the polymer film provides outstanding anti-fogging performance on cold surfaces due to the prevention of condensation. To assess the anti-fogging capability of the polymer, the epoxy layers of different thicknesses (30-105 µm) were exposed to highly humid conditions. In previous studies, the anti-fogging performance has mostly been evaluated by observation of the optical transparence, however, it may not always reveal the true and time-dependent optical property of the coatings.25,26 Fig. 3e shows real-time monitoring results of the measured diffuse reflective ratios through the coated surfaces in a highly humid environment, since fogging is attributed to the light scattering induced by the small condensed water droplets on the surface (Fig. 3f). Slightly different initial diffuse reflective ratios of the coated films were observed, presumably due to the initially-adhered water molecules on the surface in thicker films. While there is no change in the values for the 105-µm-thick film in 20 sec, the diffuse reflective ratio in a 30-µm-thick film is drastically increased, since fogging is quickly generated on the surface. When the thicker films are exposed to a humid environment for longer than 20 sec, optical clarity cannot be retained due to limitations in water-absorption capability. Thus, the same value as the saturated diffuse reflective ratio is eventually reached, such that fogging is completely formed on both surfaces within 45 sec. These results indicate that the anti-fogging capability can be controlled by varying the film thickness, which is associated with potentially saturating amounts of water in the polymer films. Further processing towards the highest possible film thickness needs to be studied.
-6-
Fig. 3. (a, b) Comparison of the anti-fogging capabilities of a; (a) bare glass substrate, (b) a thermallycured 30-µm-thick isosorbide epoxy polymer film prior to and (c) following the wear resistance test on the flux of water vapor at 50°C. (d) Anti-fogging performance of a thermally-cured isosorbide epoxy polymer film on a cold surface. (e) Diffuse reflective ratio of 30-µm- and 105-µm-thick isosorbide epoxy polymer films on the flux of water vapor at 50°C. (e) Schematic of the light scattering generated by fogging forming on the substrate. Photographs (a, b, c) were taken 5 sec after placing the samples on the top of a beaker containing water at 50°C, and (f) was taken immediately following placement on the top of an empty beaker after removal from the refrigerator at 4°C.
4. Conclusions In summary, we demonstrated a novel approach towards robust anti-fogging films derived from water-absorbing isosorbide-based epoxy resin. The films were formed on a
-7-
glass substrate by spin-coating, and were easily solidified by thermal polymerization. The hypothesized mechanism of the anti-fogging performance is attributed to the strong hydrogen bonding between the hydroxyl groups in the polymer and the water molecules. The efficient fabrication of anti-fogging films is of great interest for practical application in functional coatings that require both high optical transmittance and antifogging capabilities that are sustained in severe environments.
References [1] [2] [3] [4] [5] [6] [7] [8]
[9] [10]
[11] [12] [13] [14] [15]
[16]
[17] [18]
Kaetsu I, Yoshida M. New coating materials and their preparation by radiation polymerization. III. Antifogging coating composition. J Appl Polym Sci 1979;24:235–47. Dain SJ, Hoskin AK, Winder C, Dingsdag DP. Assessment of fogging resistance of anti-fog personal eye protection. Ophthalmic Physiol Opt 1999;19:357-61. Crebolder JM, Sloan RB. Determining the effects of eyewear fogging on visual task performance. Appl Ergon 2004;35:371-81. Margrain TH, Owen C. The misting characteristics of spectacle lenses. Ophthalmic Physiol Opt 1996;16:108-14. Zhang XT, Sato O, Taguchi M, Einaga Y, Murakami T, Fujishima A. Self-cleaning particle coating with antireflection properties. Chem Mater 2005;17:696-700. Oguri K, Iwataka N, Tonegawa A, Hirose Y, Takayama K, Nishi Y. Misting-free diamond surface created by sheet electron beam irradiation. J Mater Res 2001;16:553-7. Tricoli A, Righettoni M, Pratsinis SE. Anti-fogging nanofibrous SiO2 and nanostructured SiO2TiO2 films made by rapid flame deposition in situ annealing. Langmuir 2009;25:12578–85. Chen Y, Chang Y, Shi L, Li J, Xin Y, Yang T, Guo Z. Transparent superhydrophobic/superhydrophilic coatings for self-cleaning and anti-fogging. Appl Phys Lett 2012;101: 033701. Yu E, Kim SC, Lee HJ, Oh KH, Moon MW. Extreme wettability of nanostructured glass fabricated by non-lithographic, anisotropic etching. Sci Rep 2015;5:9362.. Sim DM, Choi MJ, Hur YH, Nam B, Chae G, Park JH, Jung YS. Ultra-High Optical Transparency of Robust, Graded-Index, and Anti-Fogging Silica Coating Derived from Si-Containing Block Copolymers. Adv Opt Mater 2013;6:428-33. England MW, Urata C, Dunderdale GJ, Hozumi A. Anti-fogging/self-healing properties of claycontaining transparent nanocomposite thin films. ACS Appl Mater Interfaces 2016;8;4318-22. Shang Q, Zhou Y. Fabrication of transparent superhydrophobic porous silica coating for selfcleaning and anti-fogging. Ceram Int 2016;42;8706-12. Fujishima A, Rao TN, Tryk DA. Titanium dioxide photocatalysis. J Photochem Photobiol C. 2000;1:1-21. Fujishima A, Zhang X, Tryk DA. TiO2 photocatalysis and related surface phenomena. Surf Sci Rep 2008;63:515–82. Sakai H, Baba R, Hashimoto K, Fujishima A, Heller A. Local detection of photoelectrochemically produced H2O2 with a “Wired” horseradish peroxidase microsensor. J Phys Chem 1995;99:11896-900. Fenouillot F, Rousseau A. Colomines G. Saint-Loup R. Pascault JP. Polymers from renewable 1,4:3,6-dianhydrohexitols (isosorbide, isomannide and isoidide): A review. Prog Polym Sci 2010;35:578-622. Łukaszczyk J, Janicki B, Kaczmarek M. Synthesis and properties of isosorbide based epoxy resin. Eur Polym J 2011;47:1601-6. Morel E, Bellenger V, Verdu J. Structure-water absorption relationships for aminecured epoxy
-8-
resins. Polymer 1985;26:1719-24. Moy P, Karasz FE. Epoxy-water interactions. Polymer Engineering & Science 1980;20:315-9. Banks L, Ellis B. The glass transition temperature of an epoxy resin and the effect of absorbed water. Polymer Bulletin. 1979;1:377-82. Stoss P, Hemmer R. 1,4:3,6-Dianhydrohexitols. Adv Carbohydr Chem Biochem 1991;49:93-173. Hamerton I. Recent developments in epoxy resins. Rapra Rev Rep 1996;8:56. Abbasian A, Ghaffarian SR, Mohammadi N, Fallahi D. The contact angle of thin-uncured epoxy films: thickness effect. Colloids Surf A Physicochem Eng Asp 2004;236:133-40. Czech Z, Urbala M, Martysz D. Investigation of the tensile properties of “epoxy resin-monomer” systems using cationic UV-crosslinkable blends. Polym Adv Technol 2004;15:387-92. Chevallier P, Turgeon SP, Sarra-Bournet C, Turcotte RL, Laroche GT, Characterization of Multilayer Anti-Fog Coatings. ACS Appl Mater Interfaces 2011;3:750-58. Chien DM, Viet NN, Van NTK, Phong NTP, Characteristics Modification of TiO2 Thin Films by Doping with Silica and Alumina for Self-Cleaning Application. J Exp Nanosci 2009;4:221-32.
[19] [20] [21] [22] [23] [24] [25] [26]
Highlights
Anti-fogging films derived from water-absorbing polymer were fabricated.
The anti-fogging performance was evaluated by in situ monitoring of optical changes.
The anti-fogging capability was controlled by varying the film thickness.
-9-
PII: DOI: Reference:
S0167-577X(16)30880-1 http://dx.doi.org/10.1016/j.matlet.2016.05.114 MLBLUE20925
To appear in: Materials Letters Received date: 15 April 2016 Revised date: 21 May 2016 Accepted date: 25 May 2016 Cite this article as: Sungjune Park, Sujin Park, Dong Hwan Jang, Hye Seung Lee and Chan Ho Park, Anti-fogging behavior of water-absorbing polymer films derived from isosorbide-based epoxy resin, Materials Letters, http://dx.doi.org/10.1016/j.matlet.2016.05.114 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Anti-fogging behavior of water-absorbing polymer films derived from isosorbide-based epoxy resin Sungjune Park1*, Sujin Park1,2, Dong Hwan Jang1, Hye Seung Lee3, Chan Ho Park3 1
Advanced Functional Materials Research Team, Automotive Research & Development Division, Hyundai Motor Group, 18280, Republic of Korea 2 School of Chemical Engineering, Sungkyunkwan University, Suwon 440-746, Republic of Korea 3 Advanced Materials Development Team, Research & Development Center, Kukdo Chemical, 08588, Republic of Korea *
Corresponding author. E-mail address: [email protected] (S.Park).
Abstract Anti-fogging films derived from isosorbide-based epoxy polymer were fabricated by film formation and subsequent thermal polymerization. The film surfaces were characterized by scanning electron microscopy, and water contact angle and diffuse reflective ratio measurements. The anti-fogging capability was evaluated by in situ monitoring of optical changes, and was controlled by varying the film thickness.
Keywords: Anti-fogging films, Water-absorbing polymer, Isosorbide epoxy resin.
1. Introduction The fogging phenomenon is generated by small water droplets condensing on the surface of an object, when the temperature of that surface is lower than that of the dew point surrounding it. As a result, light is scattered by condensed water droplets, and the surface becomes a haze.1-4 This fogging behavior limits technological applications requiring a high optical transmittance such as solar cells5 and analytical instruments such as infrared microscopes6, due to loss of function. In particular, in the case of
-1-
vehicles, fogging is often generated on the surface of the windshield due to the difference between interior- and exterior temperatures, which disturbs the drivers’ view and compromises safety. A range of surface treatment techniques to generate anti-fogging performance have therefore been developed. For instance, water droplets are barely formed and are quickly spread out on superhydrophilic surfaces (a water contact angle of 10° or less) produced by creating a geometric surface structure.7-12 Consequently, a thin water film is formed to reduce the light scattering induced by condensed water droplets. However, small structures on a micro/nanometer scale are fabricated by expensive and complicated lithographic techniques, and it is difficult to maintain shapes when pressure and abrasion from the outside are applied to the surfaces. Another well-known approach to the creation of superhydrophilic surfaces is a photochemical method using TiO2, however the surface properties are exhibited only when exposed to UV light.13-15 Here, we report a facile approach for the creation of robust anti-fogging films derived from isosorbide-based epoxy resin. The layer is fabricated by film formation and subsequent thermal polymerization. Further, the water-absorption performance (antifogging capability), which depended on film thicknesses, and the in situ measurement of the optical properties affected by the fogging phenomenon, are discussed in detail.
2. Experimental Isosorbide epoxy resin (KBM-1040, Kukdo chemical) was used to prepare the waterabsorbing polymer thin films. A 50 wt% propylene glycol mono methyl ether (PGMEA, Hannong chemical) solution was prepared, with the addition of a silane coupling agent (3-glycidoxypropylmethyldiethoxysilane) (KBM-403, Shin-etsu chemical) at 23.77 wt%
-2-
of the isosorbide epoxy resin weight to improve adhesion of the polymer to the substrate. The mixture was stirred for 1 h at 25°C. To increase thermal sensitivity, 39.8 wt% polyoxypropylenetriamine (Jeffamin T-403, Huntsman), 0.5 wt% 2-methyl imidazole (BASF), and 2.0 wt% benzyldimethylamine (Kukdo chemical) were subsequently added to the previously-formulated solution. The mixture was stirred again for 1 h at 25°C. Thin films on planar glass substrates were prepared by spin-coating in the range of 100-1000 rpm to produce polymer films with thicknesses in the range of 30-105 µm. Thermal curing was applied at 65 and 100°C for 1 h, in order to solidify the polymer films. Prior to use, the glass substrates were cleaned in ethanol and treated with ultrasonication. The cross-sectional views and thicknesses of the isosorbide epoxy polymer films were investigated using scanning force microscopy (Quanta 450, FEI). The anti-fogging capabilities of the films were evaluated by laying the films on top of a beaker containing water at 50°C. The anti-fogging performance on a cold surface was also evaluated following cooling for 30 min and removal from a refrigerator at 4°C. To investigate the mechanical strength of the polymer films, the samples were scratched 500 times by rubber with a 500 g load, and subsequently characterized by the anti-fogging test. A spectrophotometer (CM-700d, Konica Minolta) was used to characterize the optical properties. Surface wettability was characterized by water contact angle measurement after dropping a water droplet of 1 μl in volume.
3. Results and Discussion
-3-
In previous studies, isosorbide-based epoxy polymer has been recognized as a candidate material for application in the pharmaceutical and cosmetic industries, as well as a building block for polymers such as polyesters, polyethers, and polycarbonates, due to its bioderived and biodegradable properties.16-17 In particular, the water-absorption behavior in isosorbide epoxy resin is presumably linked to the network structures. For instance, the presence of OH- groups in the resin structure, since a higher hydroxyl concentration has been reported.18-20 As seen in Fig. 1, isosorbide is composed of two fused tetrahydrofuran (THF) rings with two non-equivalent hydroxyl groups21 that give the high water-absorption behavior, thus, isosorbide-based epoxy resin was used for fabrication of the anti-fogging layer in the present work.
Fig. 1. Polymeric structure of isosorbide-based epoxy resin.
Fig. 2 presents the cross-sectional views (a) and film thicknesses (b) of the thermallycured isosorbide-based epoxy polymer coated on a glass substrate. The lines along the vertical axis indicate that the majority of epoxies are well crosslinked and solidified using an amine-based curing agent by thermal treatment (Fig. 2a).22 The film thicknesses are in the range of 30-105 µm, depending on the rotation speed, however, a minimum thickness of 30 µm is limited at speeds higher than 900 rpm, due to the relatively high viscosity and strong adhesion of the epoxy materials (Fig. 2b). As shown
-4-
in Fig. 2c, the surface of the coated layer exhibits a hydrophilic state with a contact angle of 68°, which is comparable to previously reported epoxy layers.23
Fig. 2. (a) Cross-sectional SEM image of a spin-coated and thermally-cured polymer film. (b) Film thicknesses of spin-coated (at various spin speeds (rpm)) and thermally-cured polymer films. (c) Optical image of a water droplet on the polymer film. All films were thermally cured at 60 and 100°C for 1 h.
To demonstrate the anti-fogging efficiency of the polymer films, the samples were exposed to a highly humid environment. While a hazy surface is shown on the bare glass substrate due to the strong scattering of light at the curved surfaces of semispherical droplets (Fig. 3a), the isosorbide epoxy polymer film shows high clarity, and the underlying image is clearly visible though the coated surface (Fig. 3b). Crosslinkable blended systems derived from epoxy polymer have been studied in recent decades due to their favorable characteristics such as strong tensile properties.24 Fig. 3(c) shows the anti-fogging performance of the films under the same conditions following the wear resistance test. These results demonstrate the robustness of the films, since the polymer film shows excellent anti-fogging performance following the durability test. As
-5-
seen in Fig. 3(d), the underlying image is also clearly seen through the polymer films coated on both side of the substrate following cooling and removal from the refrigerator, indicating that the polymer film provides outstanding anti-fogging performance on cold surfaces due to the prevention of condensation. To assess the anti-fogging capability of the polymer, the epoxy layers of different thicknesses (30-105 µm) were exposed to highly humid conditions. In previous studies, the anti-fogging performance has mostly been evaluated by observation of the optical transparence, however, it may not always reveal the true and time-dependent optical property of the coatings.25,26 Fig. 3e shows real-time monitoring results of the measured diffuse reflective ratios through the coated surfaces in a highly humid environment, since fogging is attributed to the light scattering induced by the small condensed water droplets on the surface (Fig. 3f). Slightly different initial diffuse reflective ratios of the coated films were observed, presumably due to the initially-adhered water molecules on the surface in thicker films. While there is no change in the values for the 105-µm-thick film in 20 sec, the diffuse reflective ratio in a 30-µm-thick film is drastically increased, since fogging is quickly generated on the surface. When the thicker films are exposed to a humid environment for longer than 20 sec, optical clarity cannot be retained due to limitations in water-absorption capability. Thus, the same value as the saturated diffuse reflective ratio is eventually reached, such that fogging is completely formed on both surfaces within 45 sec. These results indicate that the anti-fogging capability can be controlled by varying the film thickness, which is associated with potentially saturating amounts of water in the polymer films. Further processing towards the highest possible film thickness needs to be studied.
-6-
Fig. 3. (a, b) Comparison of the anti-fogging capabilities of a; (a) bare glass substrate, (b) a thermallycured 30-µm-thick isosorbide epoxy polymer film prior to and (c) following the wear resistance test on the flux of water vapor at 50°C. (d) Anti-fogging performance of a thermally-cured isosorbide epoxy polymer film on a cold surface. (e) Diffuse reflective ratio of 30-µm- and 105-µm-thick isosorbide epoxy polymer films on the flux of water vapor at 50°C. (e) Schematic of the light scattering generated by fogging forming on the substrate. Photographs (a, b, c) were taken 5 sec after placing the samples on the top of a beaker containing water at 50°C, and (f) was taken immediately following placement on the top of an empty beaker after removal from the refrigerator at 4°C.
4. Conclusions In summary, we demonstrated a novel approach towards robust anti-fogging films derived from water-absorbing isosorbide-based epoxy resin. The films were formed on a
-7-
glass substrate by spin-coating, and were easily solidified by thermal polymerization. The hypothesized mechanism of the anti-fogging performance is attributed to the strong hydrogen bonding between the hydroxyl groups in the polymer and the water molecules. The efficient fabrication of anti-fogging films is of great interest for practical application in functional coatings that require both high optical transmittance and antifogging capabilities that are sustained in severe environments.
References [1] [2] [3] [4] [5] [6] [7] [8]
[9] [10]
[11] [12] [13] [14] [15]
[16]
[17] [18]
Kaetsu I, Yoshida M. New coating materials and their preparation by radiation polymerization. III. Antifogging coating composition. J Appl Polym Sci 1979;24:235–47. Dain SJ, Hoskin AK, Winder C, Dingsdag DP. Assessment of fogging resistance of anti-fog personal eye protection. Ophthalmic Physiol Opt 1999;19:357-61. Crebolder JM, Sloan RB. Determining the effects of eyewear fogging on visual task performance. Appl Ergon 2004;35:371-81. Margrain TH, Owen C. The misting characteristics of spectacle lenses. Ophthalmic Physiol Opt 1996;16:108-14. Zhang XT, Sato O, Taguchi M, Einaga Y, Murakami T, Fujishima A. Self-cleaning particle coating with antireflection properties. Chem Mater 2005;17:696-700. Oguri K, Iwataka N, Tonegawa A, Hirose Y, Takayama K, Nishi Y. Misting-free diamond surface created by sheet electron beam irradiation. J Mater Res 2001;16:553-7. Tricoli A, Righettoni M, Pratsinis SE. Anti-fogging nanofibrous SiO2 and nanostructured SiO2TiO2 films made by rapid flame deposition in situ annealing. Langmuir 2009;25:12578–85. Chen Y, Chang Y, Shi L, Li J, Xin Y, Yang T, Guo Z. Transparent superhydrophobic/superhydrophilic coatings for self-cleaning and anti-fogging. Appl Phys Lett 2012;101: 033701. Yu E, Kim SC, Lee HJ, Oh KH, Moon MW. Extreme wettability of nanostructured glass fabricated by non-lithographic, anisotropic etching. Sci Rep 2015;5:9362.. Sim DM, Choi MJ, Hur YH, Nam B, Chae G, Park JH, Jung YS. Ultra-High Optical Transparency of Robust, Graded-Index, and Anti-Fogging Silica Coating Derived from Si-Containing Block Copolymers. Adv Opt Mater 2013;6:428-33. England MW, Urata C, Dunderdale GJ, Hozumi A. Anti-fogging/self-healing properties of claycontaining transparent nanocomposite thin films. ACS Appl Mater Interfaces 2016;8;4318-22. Shang Q, Zhou Y. Fabrication of transparent superhydrophobic porous silica coating for selfcleaning and anti-fogging. Ceram Int 2016;42;8706-12. Fujishima A, Rao TN, Tryk DA. Titanium dioxide photocatalysis. J Photochem Photobiol C. 2000;1:1-21. Fujishima A, Zhang X, Tryk DA. TiO2 photocatalysis and related surface phenomena. Surf Sci Rep 2008;63:515–82. Sakai H, Baba R, Hashimoto K, Fujishima A, Heller A. Local detection of photoelectrochemically produced H2O2 with a “Wired” horseradish peroxidase microsensor. J Phys Chem 1995;99:11896-900. Fenouillot F, Rousseau A. Colomines G. Saint-Loup R. Pascault JP. Polymers from renewable 1,4:3,6-dianhydrohexitols (isosorbide, isomannide and isoidide): A review. Prog Polym Sci 2010;35:578-622. Łukaszczyk J, Janicki B, Kaczmarek M. Synthesis and properties of isosorbide based epoxy resin. Eur Polym J 2011;47:1601-6. Morel E, Bellenger V, Verdu J. Structure-water absorption relationships for aminecured epoxy
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[19] [20] [21] [22] [23] [24] [25] [26]
Highlights
Anti-fogging films derived from water-absorbing polymer were fabricated.
The anti-fogging performance was evaluated by in situ monitoring of optical changes.
The anti-fogging capability was controlled by varying the film thickness.
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