Chemical and Morphological Surface Modification of Epoxy Based Thermosets

Marcela E. Penoff, Patricia A. Oyanguren, Wido Schreiner, Pablo E. Montemartini

Composite Materials Group, Institute of Materials Science and Technology, University of Mar del Plata and National Research Council, Mar del Plata, Argentina.
Nanostructured Polymeric Materials Group, Institute of Materials Science and Technology, University of Mar del Plata and National Research Council, Mar del Plata, Argentina.
Surfaces and Interfaces Laboratory, Federal University of Parana, Politécnico, Curitiba, Brazil.

DOI: 10.4236/msa.2013.47A2001                

Abstract

Recently developed low fluorine containing polymers are advanced materials which confer advantageous properties to surfaces at a lower cost than conventional fluoropolymers (like PTFE), and are also more easily processable. Fluoropolymer surfaces are characterized by a low surface energy, high oleo and hydrophobicity, low coefficients of friction, among many other properties. This makes them desired materials in microelectronics, antifogging, antifouling and medical applications, to name a few. Fluorinated compounds are not easily coupled with macromolecules or common organic systems, and great efforts are made to compatibilize fluorinated species with hydrocarbon polymers. In this work, two chemical routes were explored in order to incorporate perfluorinated alkyl chains in an epoxy-amine based thermoset. On one side, a perfluoroalkyl thiolated molecule was used as a stabilizing ligand for silver nanoparticles, which were incorporated in the matrix polymer. On the other hand, fluorinated chains containing epoxy functionalities, were used as the matrix modifier. In the first case, fluorinated chains covering the nanoparticles, were mixed with the matrix, while in the second case, the fluoroalkyl chains were chemically linked to the network. Fluorine migration to the air—polymer interface was confirmed by X-Ray photoelectron spectroscopy (XPS). The materials hydrophobicity was then studied in terms of their contact angle with water (CA), as a function of the surface composition and the topography. Scanning electron microscopy (SEM) and atomic force microscopy (AFM), operated in moderate and light tapping modes, were used to morphologically describe the surfaces. An exhaustive surface analysis was made in order to explain the different hydrophobicity grades found.

 

Keywords

Fluoropolymer; Nanoparticles; Thermoset; Surface; Hydrophobic

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	J. P. Pascault and R. J. Williams, “Epoxy Polymers: New Materials and Innovations,” Wiley-VCH, Weinheim, 2010. doi:10.1002/9783527628704
[2]	W. Brostowa, M. Duttaa and P. Rusek, “Modified Epoxy Coatings on Mild Steel: Tribology and Surface Energy,” European Polymer Journal, Vol. 46, No. 11, 2010, pp. 2181-2189. doi:10.1016/j.eurpolymj.2010.08.006
[3]	W. Brostow, W. Chonkaewa, K. P. Menarda and T. W. Scharf, “Modification of an Epoxy Resin with a Fluoroepoxy Oligomer for Improved Mechanical and Tribological Properties,” Materials Science and Engineering, Vol. 507, No. 1-2, 2009, pp. 241-251. doi:10.1016/j.msea.2008.12.008
[4]	W. Brostow, V. M. Castano, G. Martinez-Barrera and D. Pietkiewicz, “Pressure - Volume - Temperature Properties of an Epoxy + Fluorinated Poly(aryl ether ketone) System,” Physica B: Condensed Matter, Vol. 344, No. 1-4, 2004, pp. 206-213. doi:10.1016/j.physb.2003.09.260
[5]	R. D. van de Grampel, “Surfaces of Fluorinated Polymer Systems,” Ph.D. Thesis, Technische Universiteit Eindhoven, Eindhoven, 2002.
[6]	S. C. Yoon and B. D. Ratner, “Surface Structure of Segmented Poly(ether urethanes) and Poly(ether urethane ureas) with Various Perfluoro Chain Extenders. An XRay Photoelectron Spectroscopic Investigation,” Macromolecules, Vol. 19, No. 4, 1986, pp. 1068-1079. doi:10.1021/ma00158a023
[7]	S. C. Yoon and B. D. Ratner, “Surface and Bulk Structure of Segmented Poly(ether urethanes) with Perfluoro Chain Extenders. 2. FTIR, DSC, and X-Ray Photoelectron Spectroscopic Studies,” Macromolecules, Vol. 21, No. 8, 1988, pp. 2392-2400. doi:10.1021/ma00186a016
[8]	R. N. Wenzel, “Surface Roughness and Contact Angle,” The Journal of Physical Chemistry, Vol. 53, No. 9, 1949, pp. 1466-1467. doi:10.1021/j150474a015
[9]	M. Iwamatsu, “Contact Angle Hysteresis of Cylindrical Drops on Chemically Heterogeneous Striped Surfaces,” Journal of Colloid and Interface Science, Vol. 297, No. 2, 2006, pp. 772-777. doi:10.1016/j.jcis.2005.11.032
[10]	E. Bormashenko, “General Equation Describing Wetting of Rough Surfaces,” Journal of Colloid and Interface Science, Vol. 360, No. 1, 2011, pp. 317-319. doi:10.1016/j.jcis.2011.04.051
[11]	C. Della Volpe, D. Maniglio, M. Morra and S. Siboni, “The Determination of a ‘Stable-Equilibrium’ Contact Angle on Heterogeneous and Rough Surfaces,” Colloids and Surfaces, A: Physicochemical and Engineering Aspects, Vol. 206, No. 1-3, 2002, pp. 47-67. doi:10.1016/S0927-7757(02)00072-9
[12]	Y. Funaki, K. Kumano, T. Nakao, H. Jinnai, H. Yoshida, K. Kimishima, K. Tsutsumi, Y. Hirokawa and T. Hashimoto “Influence of Casting Solvents on Microphase-Separated Structures of Poly(2-vinylpyridine)-block-polyisoprene,” Polymer, Vol. 40, No. 25, 1999, pp. 7147-7156. doi:10.1016/S0032-3861(99)00112-3
[13]	V. Rebizant, V. Abetz, F. Tournilhac, F. Court and L. Leibler, “Reactive Tetrablock Copolymers Containing Glycidyl Methacrylate. Synthesis and Morphology Control in Epoxy-Amine Networks,” Macromolecules, Vol. 36, No. 26, 2003, pp. 9889-9896. doi:10.1021/ma0347565
[14]	S. Ritzenthaler, F. Court, L. David, E. Girard-Reydet, L. Leibler and J. P. Pascault, “ABC Triblock Copolymers/ Epoxy-Diamine Blends. 1. Keys to Achiev Nanostructured Thermosets,” Macromolecules, Vol. 35, No. 16, 2002, pp. 6245-6254. doi:10.1021/ma0121868
[15]	S. P. Shah, J. D. Holmes, R. Ch. Doty, K. P. Johnston and B. A. Korgel, “Steric Stabilization of Nanocrystals in Supercritical CO2 Using Fluorinated Ligands,” Journal of the American Chemical Society, Vol. 122, No. 22, 2000, pp. 4245-4246.
[16]	B. S. Kim, H. Y. Jeong and B. K. Kim, “Surface Characterizations of Polyurethanes Having Different Types of Soft Segment,” Colloids and Surfaces A: Physicochemical and Engineering Aspects, Vol. 268, No. 1, 2005, pp. 60-67. doi:10.1016/j.colsurfa.2005.05.045
[17]	M. E. Penoff, W. Schreiner, P. A. Oyanguren and P. E. Montemartini, “Fluorinated Polyurethanes: XPS and AFM Characterization,” Macromolecular Symposia, Vol. 321-322, No. 1, 2012, pp. 186-190. doi:10.1002/masy.201251133
[18]	S. John T. Van Noort, Kees. Van der Werf, Bart G. De Grooth, Niek F. Van Hulst and Jan Greve, “Height Anomalies in Tapping Mode Atomic Force Microscopy in Air Caused by Adhesion,” Ultramicroscopy, Vol. 69, No. 2, 1997, pp. I 17-I 27.
[19]	R. Brandsch and G. Bar, “On the Factors Affecting the Contrast of Height and Phase Images in Tapping Mode Atomic Force Microscope,” Langmuir, Vol. 13, No. 24, 1997, pp. 6349-6353. doi:10.1021/la970822i
[20]	I. Revenko, Y. Tang and J. P. Santerre, “Surface Structure of Polycarbonate Urethanes Visualized by Atomic Force Microscopy,” Surface Science, Vol. 491, No. 3, 2001, pp. 346-354. doi:10.1016/S0039-6028(01)01298-5
[21]	A. Dass, R. Guo, J. B. Tracy, R. Balasubramanian, A. D. Douglas and R. W. Murray, “Gold Nanoparticles with Perfluorothiolate Ligands,” Langmuir, Vol. 24, No. 1, 2008, pp. 310-315. doi:10.1021/la702651y
[22]	L. Mo, D. Liu, W. Li, L. Li, L. Wang and X. Zhou, “Effects of Dodecylamine and Dodecanethiol on the Conductive Properties of Nano-Ag Films,” Applied Surface Science, Vol. 257, No. 13, 2011, pp. 5746-5753. doi:10.1016/j.apsusc.2011.01.090
[23]	I. Capek, “Preparation of Metal Nanoparticles in Waterin-Oil (w/o) Microemulsions,” Advances in Colloid and Interface Science, Vol. 110, No. 1-2, 2004, pp. 49-74. doi:10.1016/j.cis.2004.02.003
[24]	Y. Yuan and M. S. Shoichet, “Surface Enrichment of Poly(trifluorovinyl ether)s in Polystyrene Blends,” Macromolecules, Vol. 33, No. 13, 2000, pp. 4926-4931. doi:10.1021/ma000147a
[25]	Y. S. Kim, J. S. Lee, Q. Ji and J. E. McGrath, “Surface Properties of Fluorinated Oxetane Polyol Modified Polyurethane Block Copolymers,” Polymer, Vol. 43, No. 25, 2002, pp. 7161-7170. doi:10.1016/S0032-3861(02)00458-5
[26]	W. Ming, L. van Ravenstein, R. van de Grampel, W. van Gennip, M. Krupers, H. Niemantsverdriet and R. van der Linde, “Low Surface Energy Polymeric Films from Partially Fluorinated Photocurable Solventless Liquid Oligoesters,” Polymer Bulletin, Vol. 47, No. 3-4, 2001, pp. 321-328. doi:10.1007/s289-001-8188-7
[27]	R. D. van de Grampel, W. Ming, A. Gildenpfennig, W.J.H. van Gennip, M. J. Krupers, J. Laven, J.W. Niemantsverdriet, H. H. Brongersma and R. van der Linde, “Surface Studies of Partially Fluorinated Polymethacrylates: A Combined XPS and LEIS Analysis,” Progress in Organic Coatings, Vol. 45, No. 2-3, 2002, pp. 273-279. doi:10.1016/S0300-9440(02)00043-7
[28]	A. Synytska, D. Appelhans, Z. G. Wang, F. Simon, F. Lehmann, M. Stamm and K. Grundke, “Perfluoroalkyl End-Functionalized Oligoesters: Correlation between Wettability and End-Group Segregation,” Macromolecules, Vol. 40, No. 2, 2007, pp. 297-305. doi:10.1021/ma061139i
[29]	F. Levine, J. La Scala and W. Kosik, “Properties of Clear Polyurethane Films Modified with a Fluoropolymer Emulsion,” Progress in Organic Coatings, Vol. 69, No. 1, 2010, pp. 63-72. doi:10.1016/j.porgcoat.2010.05.006
[30]	J. M. Deitzel, W. Kisik, S. H. McKnight, N. C. Beck Tan, J. M DeSimone and S. Crette, “Electrospining of Polymer Nanofibers with Specific Surface Chemistry,” Polymer, Vol. 43, No. 3, 2002, pp. 1025-1029. doi:10.1016/S0032-3861(01)00594-8
[31]	L. Jiang, Y. Zhao and J. Zhai, “A Lotus-Leaf-like Superhydrophobic Surface: A Porous Microsphere/Nanofiber Composite Film Prepared by Electrohydrodynamics,” Angewandte Chemie International Edition, Vol. 43, No. 33, 2004, pp. 4338-4341. doi:10.1002/anie.200460333
[32]	J. Zhang, J. Li and Y. Han, “Superhydrophobic PTFE Surfaces by Extension,” Macromolecular Rapid Communications, Vol. 25, No. 11, 2004, pp. 1105-1108. doi:10.1002/marc.200400065
[33]	X. Lu, Ch. Zhang and Y. Han, “Low-Density Polyethylene Superhydrophobic Surface by Control of Its Crystallization Behavior,” Macromolecular Rapid Communications, Vol. 25, No. 18, 2004, pp. 1606-1610. doi:10.1002/marc.200400256
[34]	A. Ledo-Suárez, J. Puig, I. A. Zucchi, C. E. Hoppe, M. L. Gómez, R. Zysler, C. Ramos, M. C. Marchi, S. A. Bilmes, M. Lazzari, M. A. López-Quintela and R. J. J. Williams, “Functional Nanocomposites Based on the Infusion or In Situ Generation of Nanoparticles into Amphiphilic Epoxy Gels,” Journal of Materials Chemistry, Vol. 20, No. 45, 2010, pp. 10135-10145. doi:10.1039/c0jm01421d
[35]	M. S. Park and J. K. Kim, “Breath Figure Patterns Prepared by Spin Coating in a Dry Environment,” Langmuir, Vol. 20, No. 13, 2004, pp. 5347-5352. doi:10.1021/la035915g
[36]	T. Nishikawa, R. Ookura, J. Nishida, K. Arai, J. Hayashi, N. Kurono, T. Sawadaishi, M. Hara and M. Shimomura, “Fabrication of Honeycomb Film of an Amphiphilic Copolymer at the Air-Water Interface,” Langmuir, Vol. 18, No. 15, 2002, pp. 5734-5740. doi:10.1021/la011451f
[37]	F. Pilati, M. Montecchi, P. Fabbri, A. Synytskac, M. Messori, M. Toselli, K. Grundke and D. Pospiech, “Design of Surface Properties of PET Films: Effect of Fluorinated Block Copolymers,” Journal of Colloid and Interface Science, Vol. 315, No. 1, 2007, pp. 210-222. doi:10.1016/j.jcis.2007.06.046
[38]	H. Hasegawa and T. Hashimotot, “Morphology of Block Copolymers and Mixtures of Block Copolymers at Free Surfaces,” Polymer, Vol. 33, No. 3, 1992, pp. 475-487. doi:10.1016/0032-3861(92)90722-9