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Adhesion of Triblock Copolymer-Based Thermoreversible Gels and Pressure Sensitive Adhesives

Published online by Cambridge University Press:  01 February 2011

Kenneth R. Shull
Affiliation:
Department of Materials Science and Engineering, Northwestern University2225 N. Campus Dr. Evanston, IL 60208–3108
Alfred J. Crosby
Affiliation:
Department of Materials Science and Engineering, Northwestern University2225 N. Campus Dr. Evanston, IL 60208–3108
Cynthia M. Flanigan
Affiliation:
Department of Materials Science and Engineering, Northwestern University2225 N. Campus Dr. Evanston, IL 60208–3108
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Abstract

Triblock copolymers with poly (methyl methacrylate) (PMMA) end blocks and a poly (n-butyl acrylate) (PnBA) midblock have been synthesized as model pressure sensitive adhesives and thermoreversible gels. These materials dissolve in a variety of alcohols at temperatures above 60 °C to form freely flowing liquids. At lower temperatures the PMMA end-blocks associate so that the solutions form ideally elastic solids. In our case the solvent is 2-ethylhexanol, polymer volume fractions vary from 0.05 to 0.3, and the elastic moduli are close to 10,000 Pa. We have conducted three types of experiments to elucidate the origins of adhesion and bulk mechanical properties of these materials: 1) Weakly adhering gels: The adhesive properties of the gels are dominated by the solvent. Very little adhesion hysteresis is observed in this case, although we do observe hysteresis associated with the frictional response of the layers. 2) Strongly adhering gels. By heating the gels in contact with a PMMA surface, it is possible to bond the gels to the surface. Development of adhesion as the PMMA blocks penetrate into the PMMA substrate can be probed in this case. The cohesive strengths of the gels are found to be substantially greater than their elastic moduli, so that these materials can be reversibly extended to very high strains. These properties have enabled us to probe the origins of elastic shape instabilities that play a very important role in the behavior of thin adhesive layers. 3) Dried gels – model pressure sensitive adhesives. By removing the solvent at low temperatures, the underlying structure of the gel is preserved, giving a thin elastic layer with excellent performance as a pressure sensitive adhesive. Resistance to adhesive failure, expressed as a velocity-dependent fracture energy, greatly exceeds the thermodynamic work of adhesion. This energy is further magnified by ‘bulk’ energy dissipation when the stress applied to the adhesive layer exceeds its yield stress.

Type
Research Article
Copyright
Copyright © Materials Research Society 2000

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References

REFERENCES

1. Mortensen, K. and Pedersen, J.S., Macromolecules 26, 805 (1993).Google Scholar
2. Kleppinger, R., K., R., Mischenko, N., Overbergh, N., Koch, M.H.J., Mortensen, K. and Reynaers, H., Macromolecules 30, 7008 (1997).Google Scholar
3. Mischenko, N., Reynders, K., Koch, M.H.J., Mortensen, K., Pedersen, J.S., Fontaine, F., Graulus, R. and Reynaers, H., Macromolecules 28, 2054 (1995).Google Scholar
4. Mischenko, N., Reynders, K., Mortensen, K., Scherrenberg, R., Fontaine, F., Graulus, R. and Reynaers, H., Macromolecules 27, 2345 (1994).Google Scholar
5. Reynders, K., Mischenko, N., Kleppinger, R., Reynaers, H., Koch, M.H.J. and Mortensen, K., J. Appl. Cryst. 30, 684 (1997).Google Scholar
6. Balsara, N.P., Tirrell, M. and Lodge, T.P., Macromolecules 24, 1975 (1991).Google Scholar
7. ten Brinke, G. and Hadziioannou, G., Macromolecules 20, 486 (1987).Google Scholar
8. Yu, J.M., Jerome, R. and Teyssie, P., Polymer 38, 347 (1997).Google Scholar
9. Brown, W., Schillen, K., Almgren, M., Hvidt, S. and Bahadur, P., J. Phys. Chem. 95, 1850 (1991).Google Scholar
10. Laurer, J.H., Mulling, J.F., Khan, S.A., Spontak, R.J. and Bukovnik, R., J. of Polymer Science: Part B: Polymer Physics 36, 2379 (1998).Google Scholar
11. Kleppinger, R., van Es, M., Mischenko, N., Koch, M.H.J. and Reynaers, H., Macromolecules 31, 5805 (1998).Google Scholar
12. Quintana, J.R., Diaz, E. and Katime, I., Macromol. Chem. Phys. 197, 3017 (1996).Google Scholar
13. Reynders, K., Mischenko, N., Mortensen, K., Overbergh, N. and Reynaers, H., Macromolecules 28, 8699 (1995).Google Scholar
14. Mowery, C.L., Crosby, A.J., Ahn, D. and Shull, K.R., Langmuir 13, 6101 (1997).Google Scholar
15. Flanigan, C.M. and Shull, K.R., Langmuir 15, 4966 (1999).Google Scholar
16. Shull, K.R., Flanigan, C.M. and Crosby, A.J., Phys. Rev. Lett. 84, 3057 (2000).Google Scholar
17. Crosby, A.J. and Shull, K.R., J. Polym. Sci., Polym. Phys. 37, 3455 (1999).Google Scholar