Concentration profiles in phase-separating photocuring coatings

  • Hirokazu Yoshihara
  • Masato YamamuraEmail author


We directly measured the local composition profiles in phase-separating photocurable thin films using confocal Raman spectroscopy. To avoid light scattering at phase interfaces, we developed a novel technique to replace the solvent with a monomer to match the reflective indices in the cured films. The results indicated that the concentration distribution of the polymer was uniform in solvent-free monomer/initiator binary solutions, while it was spatially nonuniform when the solvent-based films were thermodynamically unstable and promoted reaction-induced phase separation upon UV irradiation on the top surface. In the latter case, the film exhibited a dual-layer structure, in which the polymer concentration was almost uniform near the top surface, while concentration gradients developed near the bottom surface. The thickness of the top layer with a uniform concentration profile increased with the increase in the UV light intensity. These results implied that the propagation of the reaction front and the resulting light-driven transport of the solvent toward the bottom coating layer played key roles in the formation of nonuniform concentration profiles in photocuring solution coatings.


UV curing Coating Reaction-induced phase separation Confocal Raman spectroscopy 



  1. 1.
    Scharber, MC, Sariciftci, NS, “Efficiency of Bulk-Heterojunction Organic Solar Cells.” Prog. Polymer Sci., 38 1929–1940 (2013)CrossRefGoogle Scholar
  2. 2.
    Deibel, C, “Photocurrent Generation in Organic Solar Cells.” Semicond. Semimet., 85 297–330 (2011)CrossRefGoogle Scholar
  3. 3.
    Costa, CM, Nunes-Pereira, J, Rodrigues, LC, Silva, MM, Gomez Ribelles, JL, Lanceros-Mendez, S, “Novel Poly(Vinylidene Fluoride-Trifluoro Ethylene)/Poly(Ethylene Oxide) Blends for Battery Separators in Lithium-Ion Applications.” Electrochim. Acta, 88 473–476 (2013)CrossRefGoogle Scholar
  4. 4.
    Huang, Y, Huang, QL, Liu, H, Zhang, CX, You, YW, Li, NN, Xiao, CF, “Preparation, Characterization, and Applications of Electrospun Ultrafine Fibrous PTFE Porous Membranes.” J. Membr. Sci., 523 317–326 (2017)CrossRefGoogle Scholar
  5. 5.
    Lee, H, Segets, D, Süß, S, Peukert, W, Chen, SC, Pui, DYH, “Liquid Filtration of Nanoparticles Through Track-Etched Membrane Filters Under Unfavorable and Different Ionic Strength Conditions: Experiments and Modeling.” J. Membr. Sci., 524 682–690 (2017)CrossRefGoogle Scholar
  6. 6.
    Chen, SC, Segets, D, Ling, TY, Peukert, W, Pui, DYH, “An Experimental Study of Ultrafiltration for Sub-10 nm Quantum Dots and Sub-150 nm Nanoparticles Through PTFE Membrane and Nuclepore Filters.” J. Membr. Sci., 497 153–161 (2016)CrossRefGoogle Scholar
  7. 7.
    Wu, Z, Cui, Z, Cui, T, Li, T, Qin, S, Li, J, “Fabrication of PVDF-Based Blend Membrane with a Thin Hydrophilic Deposition Layer and a Network Structure Supporting Layer Via the Thermally Induced Phase Separation Followed by Non-solvent Induced Phase Separation Process.” Appl. Surf. Sci., 419 429–438 (2017)CrossRefGoogle Scholar
  8. 8.
    Luo, H, Scriven, LE, Francis, LF, “Cryo-SEM Studies of Latex/Ceramic Nanoparticle Coating Microstructure Development.” J. Colloid Interface Sci., 316 500–509 (2007)CrossRefGoogle Scholar
  9. 9.
    Liang, Z, Chen, W, Liu, J, Wang, S, Zhou, Z, Li, W, Sun, G, Xin, Q, “FT-IR Study of the Microstructure of Nafion Membrane.” J. Membr. Sci., 233 39–44 (2004)CrossRefGoogle Scholar
  10. 10.
    Wang, M, Feindel, KW, Bergens, SH, Wasylishen, RE, “In situ Quantification of the In-plane Water Content in the Nafion Membrane of an Operating Polymer-Electrolyte Membrane Fuel Cell Using 1H Micro-Magnetic Resonance Imaging Experiments.” J. Power Sources, 195 7316–7322 (2010)CrossRefGoogle Scholar
  11. 11.
    Wu, J, Melo, LGA, Zhu, X, West, MM, Berejnov, V, Susac, D, Stumper, J, Hitchcock, AP, “4D Imaging of Polymer Electrolyte Membrane Fuel Cell Catalyst Layers by Soft X-ray Spectro-Tomography.” J. Power Sources, 381 72–83 (2018)CrossRefGoogle Scholar
  12. 12.
    Jain, M, Annapoorni, S, “Raman Study of Polyaniline Nanofibers Prepared by Interfacial Polymerization.” Synth. Met., 160 1727–1732 (2010)CrossRefGoogle Scholar
  13. 13.
    Izumi, CMS, Temperini, MLA, “FT-Raman Investigation of Biodegradable Polymers: Poly(3-Hydroxybutyrate) and Poly(3-Hydroxybutyrate-co-3-Hydroxyvalerate).” Vib. Spectrosc., 54 127–132 (2010)CrossRefGoogle Scholar
  14. 14.
    Deabate, S, Fatnassi, R, Sistat, P, Huguet, P, “In Situ Confocal-Raman Measurement of Water and Methanol Concentration Profiles in Nafion Membrane Under Cross-Transport Conditions.” J. Power Sources, 176 39–45 (2008)CrossRefGoogle Scholar
  15. 15.
    Marzouki, A, Lusson, A, Jomard, F, Sayari, A, Galtier, P, Ouelati, M, Sallet, V, “SIMS and Raman Characterizations of ZnO: N Thin Films Grown by MOCVD.” J. Cryst. Growth, 312 3063–3068 (2010)CrossRefGoogle Scholar
  16. 16.
    Lashkarev, G, Karpyna, V, Yaremko, A, “Multi-phonon Excitations in ZnO Textured Crystalline Films by Raman Spectroscopy.” Thin Solid Films, 520 6499–6502 (2012)CrossRefGoogle Scholar
  17. 17.
    Vishwas, M, Rao, KN, Chakradhar, RPS, “Influence of Annealing Temperature on Raman and Photoluminescence of Electron Beam Evaporated TiO2 Thin Films.” Mol. Biomol. Spectrosc., 99 33–36 (2012)CrossRefGoogle Scholar
  18. 18.
    Zolkin, A, Semerikova, A, Chepkasov, S, Khomyakov, M, “Characteristics of the Raman Spectra of Diamond-Like Carbon Films.” Mater. Today Proc., 4 11480–11485 (2017)CrossRefGoogle Scholar
  19. 19.
    Scharfer, P, Schabel, W, Kind, M, “Mass Transport Measurements in Membranes by Means of In situ Raman Spectroscopy: First Results of Methanol and Water Profiles in Fuel Cell Membranes.” J. Membr. Sci., 303 37–42 (2007)CrossRefGoogle Scholar
  20. 20.
    Jeck, S, Scharfer, P, Schabel, W, Kind, M, “Water Sorption in Poly(Vinyl Alcohol) Membranes: An Experimental and Numerical Study of Solvent Diffusion in a Crosslinked Polymer.” Chem. Eng. Process., 50 543–550 (2011)CrossRefGoogle Scholar
  21. 21.
    Jeck, S, Scharfer, P, Schabel, W, Kind, M, “Water Sorption in Poly(Vinyl Alcohol) Membranes: In situ Characterisation of Solvent-Induced Structural Rearrangement.” J. Membr. Sci., 389 162–172 (2012)CrossRefGoogle Scholar
  22. 22.
    Muller, M, Scharfer, P, Kind, M, Schabel, W, “Influence of Non-volatile Additives on the Diffusion of Solvents in Polymeric Coatings.” Chem. Eng. Process., 50 551–554 (2011)CrossRefGoogle Scholar
  23. 23.
    Curtis, CL, Doan, VV, Credo, GM, Sailor, MJ, “Observation of Optical Cavity Modes in Photoluminescent Porous Silicon Films.” J. Electrochem. Soc., 140 (12) 3492–3494 (1993)CrossRefGoogle Scholar
  24. 24.
    Seo, SJ, Cha, HJ, Kang, YS, Kang, MS, “Pore-Fiilled Electrolyte Membranes for Facile Fabrication of Long-Term Stable Dye-Sensitized Solar Cells.” Electrochim. Acta, 173 425–431 (2015)CrossRefGoogle Scholar
  25. 25.
    Chen, HS, Lue, SJ, Tung, YL, Cheng, KW, Huang, FY, Ho, KC, “Elucidation of Electrochemical Properties of Electrolyte-Impregnated Micro-porous Ceramic Films as Framework Supports in Dye-Sensitized Solar Cells.” J. Power Sources, 196 4162–4172 (2011)CrossRefGoogle Scholar
  26. 26.
    Guthrle, J, Jeganathan, MB, Otterburn, MS, Woods, J, “Light Screening Effects of Photoinitiators in UV Curable Systems.” Polym. Bull., 15 51–58 (1986)Google Scholar
  27. 27.
    da Silva Bartolo, PJ, “Photo-Curing Modelling: Direct Irradiation.” Adv. Manuf. Technol., 32 480–491 (2007)CrossRefGoogle Scholar
  28. 28.
    Seubert, CM, Nichols, ME, “Epoxy Thiol Photolatent Base Clearcoats: Curing and Formulation.” J. Coat. Technol. Res., 7 (5) 615–622 (2010)CrossRefGoogle Scholar
  29. 29.
    Ozaki, T, Koto, T, Nguyen, TV, Nakanishi, H, Norisuye, T, Miyata, QTC, “The Roles of the Trommsdorff-Norrish Effect in Phase Separation of Binary Polymer Mixtures Induced by Photopolymerization.” Polymer, 55 1809–1816 (2014)CrossRefGoogle Scholar
  30. 30.
    Shukutani, T, Myojo, T, Nakanishi, H, Norisuye, T, Miyata, QTC, “Tricontinuous Morphology of Ternary Polymer Blends Driven by Photopolymerization: Reaction and Phase Separation Kinetics.” Macromolecules, 47 4380–4386 (2014)CrossRefGoogle Scholar
  31. 31.
    Jaiser, S, Muller, M, Baunach, M, Bauer, W, Scharfer, P, Schabel, W, “Investigation of Film Solidification and Binder Migration During Drying of Li-Ion Battery Anodes.” J. Power Sources, 318 210–219 (2016)CrossRefGoogle Scholar
  32. 32.
    Yoshihara, H, Yamamura, M, “Formation Mechanism of Asymmetric Porous Polymer Films by Photo-induced Phase Separation in the Presence of Solvent.” submittedGoogle Scholar
  33. 33.
    Liu, T, Ozisk, R, Siegel, RW, “Phase Separation and Surface Morphology of Spin-Coated Films of Polyetherimide/Polycaprolactone Immiscible Polymer Blends.” Thin Solid Films, 515 2965–2973 (2007)CrossRefGoogle Scholar
  34. 34.
    Kragt, AJJ, Broer, DJ, Schenning, APHJ, “Easily Processable and Programmable Responsive Semi-Interpenetrating Liquid Crystalline Polymer Network Coatings with Changing Reflectivities and Surface Topographies.” Adv. Func. Mater., 28 1704756 (2018)CrossRefGoogle Scholar
  35. 35.
    Tomlinson, WJ, Chandross, EA, Weber, HP, Aumiller, GD, “Multicomponent Photopolymer Systems for Volume Phase Holograms and Grating Devices.” Appl. Opt., 15 534–541 (1976)CrossRefGoogle Scholar

Copyright information

© American Coatings Association 2019

Authors and Affiliations

  1. 1.Dai Nippon Printing Co., Ltd.TsukubaJapan
  2. 2.Department of Applied ChemistryKyushu Institute of TechnologyKitakyushuJapan

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