This paper reported the effects that the key dielectric barrier discharge (DBD) operating parameters, discharge power, processing speed, processing duration and electrode configurations, have on producing wettability changes and on uniformity in the PMMA surface region. The results obtained indicate that DBD plasma processing is an effective method for the controlled surface modification of PMMA. Relatively short exposures to the atmospheric pressure discharge produces significant wettability changes at the PMMA surface, as indicted by pronounced reductions in the water contact angle measured. It was observed that the wettability of the resultant surface shows no significant differences in respect to sites in orientation parallel (L-direction) or perpendicular (T-direction) to the electrode long axis. However, the resultant surface shown higher standard deviation (S.D.) of contact angle in T-direction than that in L-direction. Analysis of the role of each of the operating parameters concerned shows that they have a selective effectiveness with respect to resultant surface modification in terms of uniformity of modification and wettability. The number of treatment cycles and the discharge power used were found to have the most significant effects on the homogeneity of the resultant PMMA surface changes in L- and T-orientation, respectively. The number of treatment cycles was found to be the dominant factor (at significance level of 0.05) in respect of water contact angle changes at the processed PMMA surface in both orientations. The driven metal electrodes (stainless steel or aluminium) were apparently superior to the driven dielectric electrode (ceramic or quartz) configurations. The grounded electrode in each case was a silicone rubber-covered aluminium plate. The nature and scale of the surface changes that originate from the various processing conditions employed have been considered so as to determine the optimum treatment conditions in respect of processing outcomes, properties and any orientation dependence. It was revealed that higher processing speeds and longer processing durations are key for uniformity along the electrode axial orientation within the test range employed, while lower processing speeds and short exposure durations are key considerations, in the corresponding perpendicular orientation. In general, longer processing durations (low processing speeds and a high number of treatment cycles) and higher plasma powers induced greater changes in the surface wettability of the PMMA, as demonstrated by the observed water contact angles. This behaviour is taken to indicate that different combinations of DBD operating parameters and electrodes produce discharge conditions that can result in different plasma chemical processes in respect of uniformity, treatment efficiency and orientation dependence. The comparison of the processing outcomes between PMMA and PET revealed that the operating parameters have the similar selective effectiveness on both polymers, indicating the obtained results may be used as a general guidance in controllable surface processing by DBD technique.
Bibliographical noteReference text:  L.-A. O'Hare, J.A. Smith, S.R. Leadley, B. Parbhoo, A.J. Goodwin and J.F. Watts, Surf. Interface Anal. 33 (2002), p. 617. Full Text via CrossRef
 C.Z. Liu, J.Q. Wu, L.Q. Ren, J. Tong, J. Li, N.Y. Cui, N.M.D. Brown and B.J. Meenan, Mater. Chem. Phys. 85 (2004) (2–3), p. 340. Article | PDF (346 K) | View Record in Scopus | Cited By in Scopus (12)
 H. Biederman, M. Zeuner, J. Zalman, P. Bilkova, D. Slavinska, V. Stelmasuk and A. Boldyreva, Thin Solid Films 392 (2001), p. 208. Article | PDF (483 K) | View Record in Scopus | Cited By in Scopus (36)
 C.Z. Liu, S.M. Green, R.D. Arnell, A.R. Gibbons, L.Q. Ren and J. Tong In: T.S. Sudarsham, K.A. Khor and M. Jeandin, Editors, Surface Modification Technologies XIII, ASM International, Ohio (1999), p. 1. Abstract | PDF (178 K) | MathSciNet | View Record in Scopus | Cited By in Scopus (3)
 M. Heise, W. Neff, O. Franken, P. Muranyi and J. Wunderlich, Plasmas Polym. 9 (2004) (1), p. 23. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (26)
 M. Dhainaut, E. Odic, M. Goldman, A. Goldman, C. Karimi, Universite Paris Sud—CNRS, Gif-sur-Yvette Cedex, France 2004, p. 1–5.
 M.V. Kozlov, M.V. Sokolova, A.G. Temnikov, V.V. Timatkov, I.P. Vereshchagin, 2004.
 T. Nozaki, Y. Miyazaki, Y. Unno and K. Okazaki, J. Phys., D, Appl. Phys. 34 (2001), p. 3383. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (38)
 T. Nozaki, T. Unno, Y. Miyazaki and K. Okazaki, 15th International Symposium on Plasma Chemistry, Orleans, France, July 2001 (2001), pp. 77–83.
 L.F. Dong, Y.F. He, Z.Q. Yin and Z.F. Chai, Plasma Sources Sci. Technol. 13 (2004), p. 164. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (11)
 A. Chirokov, A. Gutsol, A. Fridman, K.D. Sieber, J.M. Grace and K.S. Robinson, Plasma Sources Sci. Technol. 13 (2004), p. 623. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (21)
 C.Z. Liu, N.M.D. Brown and B.J. Meenan, Surf. Sci. 575 (2005) (3), p. 273. Article | PDF (916 K) | Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (2)
 C.Z. Liu, N.M.D. Brown and B.J. Meenan, Appl. Surf. Sci. 252 (2006), p. 2297. Article | PDF (597 K) | View Record in Scopus | Cited By in Scopus (7)
 A. Bogaerts, E. Neyts, R. Gijbels and J. van der Mullen, Spectrochim. Acta, Part B: Atom. Spectrosc. 57 (2002), p. 609. Article | PDF (1207 K) | View Record in Scopus | Cited By in Scopus (121)
 S. Ishikawa, K. Yukimura, K. Matsunaga and T. Maruyama, Surf. Coat. Technol. 130 (2000), p. 52. Article | PDF (159 K) | View Record in Scopus | Cited By in Scopus (19)
 Y. Babukutty, R. Prat, K. Endo, M. Kogoma, S. Okazaki and M. Kodama, Langmuir 15 (1999), p. 7055. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (23)
 N.Y. Cui, D.J. Upadhyay, C.A. Anderson and N.M.D. Brown, Surf. Coat. Technol. 192 (2005), p. 94. Article | PDF (271 K) | View Record in Scopus | Cited By in Scopus (8)
 W.J. Diamond, Practical Experiment Designs: for Engineers and Scientists, John Wiley and Sons (2001).
 L.Q. Ren, Experiment Design and Analysis, Science and Technology Publishing Ltd of Jinlin Province, Changchun, P. R. China (2001).
 A. Grill, Cold Plasma in Materials Fabrication, IEEE Press, New York (1994).
 V.I. Gibalov and G.J. Pietsch, J. Phys., D, Appl. Phys. 33 (2000), p. 2618. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (146)
 R.J. Carman and R.P. Mildren, J. Phys., D, Appl. Phys. 33 (2000), p. L99. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (14)
 U. Kogelschatz, 2003.http://webferret.search.com/click?wf,DBD+PLASMA,,mmlab.dlut.edu.cn%2Fplasma-16.pdf,,aol.
 D.J. Upadhyay, N.Y. Cui, C.A. Anderson and N.M.D. Brown, Surf. Sci. 560 (2004), p. 246. Article | PDF (416 K) | View Record in Scopus | Cited By in Scopus (5)
- Surface modification
- Dielectric barrier discharge
- Atmospheric plasma processing
- Poly(methyl methacrylate) (PMMA)
- Statistical analysis