Diblock Copolymers at Surfaces

Abstract

The surface properties of symmetric microphase separated diblock copolymers of polystyrene (PS) and polymethylmethacrylate (PMMA) were investigated using X-ray photoelectron spectroscopy (XPS), the specular reflectivity of neutrons and secondary ion mass spectrometry (SIMS). PS, the lower surface energy component, exhibited a preferential affinity for the free surface. For copolymers that are far from the bulk microphase separation transition (MST), the surface consists of a layer of pure PS. When the system is close to the MST the surface is a mixture of PS and PMMA. The PS surface excess can be described bya N-1/2 dependence, where N is the number of segments that comprise the copolymer chain. It is shown that the surface undergoes an ordering transition at a temperature T2 that is above that of the bulk MST. The ordering of the bulk lamellar morphology is induced by an ordering at the surface. This is analogous to the ferromagnetic order observed in systems such as Gd at temperatures above the bulk Curie temperature. The results here are discussed in light of previous work on copolymer surfaces and in light of mean field theory.

This is a preview of subscription content, access via your institution.

References

  1. 1

    I. Goodman, Ed., Developments in Block copolymers (Applied Science, New York, 1982).

  2. 2

    L. Leibler, Macromolecules 13, 1602 (1980).

    CAS  Article  Google Scholar 

  3. 3

    T. Oht, K, Kawasaki, Macromolecules 19, 2621 (1986). A.N. Semenov, Sov. Phys. JETP, 61, 733 (1985).

    Google Scholar 

  4. 4

    J. M. Blakley, in Chemistry and Physics of Solid Surfaces, Vol 2, edited by R. Vanselow (CRC Press, Boca Raton, FL, 1979).

  5. 5

    M.J. Owen and T.C. Kendrick, Macromolecules, 3, 458 (1970).

    CAS  Article  Google Scholar 

  6. 6

    A.K. Rostogi and L.E. St. Pierre, J. Colloid and Inf. Sce. 31, 168 (1969).

    Article  Google Scholar 

  7. 7

    R.L. Schmitt, J.A. Gardella Jr., J.H. Magill, L. Salvati, Jr., and R.L. Chin, Macromolecules 18, 2675 (1985)

    CAS  Article  Google Scholar 

  8. 8

    H.R. Thomas and J.J. O’Malley, Macromolecules 12, 323 (1979).

    CAS  Article  Google Scholar 

  9. 9

    N.M. Patel, D.W. Dwight, J.L. Hendrick, D.C. Webster and J.E. McGarth, Macromolecules, 21, 2689 (1988).

    CAS  Article  Google Scholar 

  10. 11

    J.E. McGarth, D.W. Dwight. J.S. Riffle, T.F. Davidson, D.C. Webber and R. Vishwanathan, Polym. Prepr. Am Chem. Soc. Div. Polym. Chem 20(2), 528 (1979)

  11. 12

    C.S. Henkee, E.L. Thomas and L.J. Fetters, J. Materials Sci. 23, 1685 (1988).

    CAS  Article  Google Scholar 

  12. 13

    H. Hasegawa, T. Hashimoto, Macromolecules 18, 589 (1985).

    CAS  Article  Google Scholar 

  13. 14

    S.H. Anastasiadis, T.P. Russell, S.K. Satija and C.K. Majkzrak, Physical Review Letters 62, 1852 (1989).

    CAS  Article  Google Scholar 

  14. 15

    S.H. Anastasiadis, T.P. Russell, S.K. Satija and C.K. Majkzrak, J. Chem. Phys. (submitted).

  15. 16

    G. Coulon, T.P. Russell, V.R. Deline and P.F. Green, Macromolecules, 22, 2581 (1989).

    CAS  Article  Google Scholar 

  16. 17

    G.L. Gaines, Macromolecules, 14, 208 (1981)

    CAS  Article  Google Scholar 

  17. 18

    K. Binder, In Phase Transitions and Critical Phenomena, C. Domb, J.L. Lebowitz, Eds.; Academic Press, New York, Vol. 8 (1983).

  18. 19

    C. Rau and M. Robert, Physical Review Letters, 58, 2714 (1987).

    CAS  Article  Google Scholar 

  19. 20

    P.G. deGennes, Scaling Concepts in Polymer Physics (Cornell University Press, Ithaca, New York, 1979).

  20. 21

    P.F. Green, T.P. Russell, R. Jerome and M. Granville, Macromolecules, 21, 3266 (1988).

    CAS  Article  Google Scholar 

  21. 22

    p.F. Green, T.P. Russell, R. Jerome and M. Granville, Macromolecules, 22, 908 (1989).

    CAS  Article  Google Scholar 

  22. 23

    P.F. Green, T.M. Christensen, T.P. Russell and R. Jerome, Macromolecules, 22, 2189 (1989).

    CAS  Article  Google Scholar 

  23. 24

    P.F. Green, T.M. Christensen, T.P. Russell and R. Jerome, J. Chem. Phys. (in press).

  24. 25

    D.T. Clark, J. Peeling and J.M. O’Malley, J. Polym. Sci., Polym. Chem. Ed. 14, 543 (1976). D.T. Clark and H.R. Thomas, J. Polym. Sce. 16, 791 (1978)

    CAS  Google Scholar 

  25. 26

    J. Als-Nielson, In Structure and Dynamics of Surfaces II, edited by M. Schommers and P. von Blanckenhagen (springer-Verlag, Berlin, 1987).

  26. 27

    G.H. Fredrickson, Macromolecules 20, 2535 (1987).

    CAS  Article  Google Scholar 

  27. 28

    S. Wu, Polymer Interfaces and Adhesion (Marcel Dekker, New York, New York, 1982) p. 73.

  28. 29

    The angle resolved measurements of these samples made by the slow solvent evaporation process showed variations only for the shortest copolymer system, the PMMA fraction varied from 0.25 to 0.18 in going from 90° to 20°.

  29. 30

    The angle resolved measurements showed variations only for the shortest copolymer system, the PMMA fraction varied from 0.22 to 0.17 in going from 90° to 20°.

  30. 31

    Many of the films, particularly the high N systems, that were not annealed long enough yielded values of ψ1 that were closer to 0.5. After longer anneals they reached their equilibrium values.As N increased the time required to reach equilibrium increased appreciaby.

Download references

Author information

Affiliations

Authors

Corresponding author

Correspondence to Thomas M. Christensen.

Additional information

This work was supported in part by U. S. DOE under Contract DE-AC046-DP00789

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Green, P.F., Christensen, T.M., Russell, T.P. et al. Diblock Copolymers at Surfaces. MRS Online Proceedings Library 171, 317–327 (1989). https://doi.org/10.1557/PROC-171-317

Download citation