Polymer Chemistry Group

Radiation Chemistry

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The Interaction of High Energy Radiation with Polymeric Materials

Polymeric materials are exposed to high energy radiation either deliberately to alter their properties, or inadvertently during their use in high dose environments. As a consequence, an understanding of the how radiation modifies the polymer structure, and hence properties, is essential for many applications. In addition, the understanding of the degradation of polymers with light or heat can benefit from knowledge of the reaction pathways of radical and charged species formed on irradiation with high energy photons.

Polymers either crosslink or undergo scission on exposure to radiation, and the final properties of the polymers depend critically on the balance of these two main reaction pathways.

Mechanism of crosslinking

Crosslinking

Mechanism of chain scission

Scission

The UQ Polymer Chemistry Group has for many years been involved in the study of the effects of ionising radiation on polymers. The group has contributed to a detailed understanding of the relationship between polymer structure and balance of radio-chemical reactions.

Currently the emphasis of our research is the modification of polymer surfaces by grafting through the use of high-energy radiation. The target applications are hydrophilic surfaces, proton exchange membranes, polymers for combinatorial chemistry, to name a few applications. In addition we are studying the radiation degradation of high performance polyimides filled with carbon nanotubes.

Raman map of grafted PFA
Figure 1. Raman stack plot of vapour-phase grafted PFA

Publications (selected)

1. J. Forsythe, D. Hill, H. Liu, J. O'Donnell, S. Perera, P. Pomery, and A. Whittaker, "Radiation effects in polymeric materials: Chemical and physical analysis by NMR spectroscopy," Radiation Research, International Congress of Radiation Research, 11th, Dublin, Ireland, July 18-23, 1999, vol. 2, pp. 75-77, 2000.
2. J. S. Forsythe, D. J. T. Hill, A. L. Logothetis, P. J. Pomery, and A. K. Whittaker, "The use of crosslinking promoters in the .gamma.-radiolysis of poly (tetrafluoroethylene-co-perfluoromethylvinyl ether). II," in J. Appl. Polym. Sci., vol. 75, 2000, pp. 1447-1452.
3. J. S. Forsythe and D. J. T. Hill, "The radiation chemistry of fluoropolymers," Progress in Polymer Science, vol. 25, pp. 101-136, 2000.
4. D. J. T. Hill, C. M. L. Preston, A. K. Whittaker, and S. M. Hunt, "The radiation chemistry of poly(dimethylsiloxane)," Macromolecular Symposia, vol. 156, pp. 95-102, 2000.
5. D. J. T. Hill, S. Mohajerani, P. J. Pomery, and A. K. Whittaker, "An ESR study of the radiation chemistry of poly(tetrafluoroethylene-co-hexafluoropropylene) at 77 and 300 K," Radiation Physics and Chemistry, vol. 59, pp. 295-302, 2000.
6. M. A. Alexander, D. J. T. Hill, J. W. Connell, and K. A. Watson, "A study of the vacuum g-radiolysis of two aromatic polyimide fluoropolymers containing phenylphosphine oxide," High Performance Polymers, vol. 13, pp. 67-78, 2001.
7. M. A. Alexander, T. T. Le, D. J. T. Hill, J. W. Connell, and K. A. Watson, "The behaviour of phenylphosphine oxide containing polyimides in a water plasma following g-radiolysis," Radiation Physics and Chemistry, vol. 62, pp. 171-177, 2001.
8. M. A. Alexander, D. J. T. Hill, J. W. Connell, and K. A. Watson, "A study of the oxidation of two aromatic polyimide fluoropolymers containing phenylphosphine oxide by a water plasma and g-radiolysis in air," High Performance Polymers, vol. 13, pp. 55-65, 2001.
9. F. Cardona, D. J. T. Hill, G. George, J. Maeji, R. Firas, and S. Perera, "Thermal characterization of copolymers obtained by radiation grafting of styrene onto poly(tetrafluoroethylene-perfluoropropylvinylether) substrates: thermal decomposition, melting behavior and low-temperature transitions," Polymer Degradation and Stability, vol. 74, pp. 219-227, 2001.
10. T. R. Dargaville, D. J. T. Hill, and A. K. Whittaker, "An ESR study of irradiated poly(tetrafluoroethylene-co-perfluoropropyl vinyl ether) (PFA)," Radiation Physics and Chemistry, vol. 62, pp. 25-31, 2001.
11. S. Devasahayam, D. J. T. Hill, and J. W. Connell, "A comparative study of the radiation resistance of four optically transparent polyimides," Radiation Physics and Chemistry, vol. 62, pp. 189-194, 2001.
12. J. S. Forsythe, D. J. T. Hill, S. Mohajerani, and A. K. Whittaker, "Solid state 19F NMR determination of new structure formation in FEP following radiolysis at 300 and 363 K," Radiation Physics and Chemistry, vol. 60, pp. 439-444, 2001.
13. J. S. Forsythe, D. J. T. Hill, and A. K. Whittaker, "The use of NMR for determination of new structures in irradiated TFE/PMVE fluoropolymers," Radiation Physics and Chemistry, vol. 60, pp. 609-615, 2001.
14. K. K. Gleason, D. J. T. Hill, K. K. S. Lau, S. Mohajerani, and A. K. Whittaker, "The use of 19F NMR for new structure determination in the radiolysis of FEP," Nuclear Instruments & Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms, vol. 185, pp. 83-87, 2001.
15. D. J. T. Hill, C. M. L. Preston, and A. K. Whittaker, "NMR study of the gamma radiolysis of poly(dimethyl siloxane) under vacuum at 303 K," Polymer, vol. 43, pp. 1051-1059, 2001.
16. D. J. T. Hill, B. K. Choi, H. K. Ahn, and E. J. Choi, "An ESR study of the gamma radiolysis of aromatic polyesters containing isomeric naphthalene links," Radiation Physics and Chemistry, vol. 62, pp. 195-201, 2001.
17. D. J. T. Hill, C. M. L. Preston, D. J. Salisbury, and A. K. Whittaker, "Molecular weight changes and scission and crosslinking in poly(dimethyl siloxane) on gamma radiolysis," Radiation Physics and Chemistry, vol. 62, pp. 11-17, 2001.
18. D. J. T. Hill, L. Y. Shao, P. J. Pomery, and A. K. Whittaker, "The radical homopolymerization of N-phenylmaleimide, N-n-hexylmaleimide and N-cyclohexylmaleimide in tetrahydrofuran," Polymer, vol. 42, pp. 4791-4802, 2001.
19. M. Lepage, A. K. Whittaker, L. Rintoul, S. A. J. Back, and C. Baldock, "Modelling of post-irradiation events in polymer gel dosimeters," Physics in Medicine & Biology, vol. 46, pp. 2827-2839, 2001.
20. M. Lepage, A. K. Whittaker, L. Rintoul, S. A. J. Back, and C. Baldock, "The relationship between radiation-induced chemical processes and transverse relaxation times in polymer gel dosimeters," Physics in Medicine & Biology, vol. 46, pp. 1061-1074, 2001.
21. Zainuddin, D. J. T. Hill, and T. T. Le, "An ESR study on g-irradiated poly(vinyl alcohol)," Radiation Physics and Chemistry, vol. 62, pp. 283-291, 2001.
22. T. R. Dargaville, G. A. George, D. J. T. Hill, U. Scheler, and A. K. Whittaker, "High-Speed MAS 19F NMR Analysis of an Irradiated Fluoropolymer," Macromolecules, vol. 35, pp. 5544-5549, 2002.
23. S. Devasahayam, D. J. T. Hill, P. J. Pomery, and A. K. Whittaker, "The radiation chemistry of Ultem at 77 K as revealed by ESR spectroscopy," Radiation Physics and Chemistry, vol. 64, pp. 299-308, 2002.
24. M. M. Faragalla, D. J. T. Hill, and A. K. Whittaker, "The copolymerization of N-vinyl-2-pyrrolidone with 2-hydroxyethyl methacrylate," Polymer Bulletin (Berlin, Germany), vol. 47, pp. 421-427, 2002.
25. P. Y. Ghi, D. J. T. Hill, and A. K. Whittaker, "1H NMR Study of the States of Water in Equilibrium Poly(HEMA-co-THFMA) Hydrogels," Biomacromolecules, vol. 3, pp. 991-997, 2002.
26. P. Y. Ghi, D. J. T. Hill, and A. K. Whittaker, "PFG-NMR Measurements of the Self-Diffusion Coefficients of Water in Equilibrium Poly(HEMA-co-THFMA) Hydrogels," Biomacromolecules, vol. 3, pp. 554-559, 2002.
27. D. J. T. Hill and A. K. Whittaker, "NMR studies of the radiation modification of polymers," Annual Reports on NMR Spectroscopy, vol. 46, pp. 1-35, 2002.
28. F. Cardona, D. J. T. Hill, P. J. Pomery, and A. K. Whittaker, "A study of the radiation degradation of styrene/alkane and a-methylstyrene/alkane copolymers," Polymer International, vol. 52, pp. 1711-1718, 2003.
29. T. R. Dargaville, G. A. George, D. J. T. Hill, and A. K. Whittaker, "Investigation of the Vapor-Phase Grafting of Styrene onto PFA," Macromolecules, vol. 36, pp. 8276-8281, 2003.
30. T. R. Dargaville, G. A. George, D. J. T. Hill, and A. K. Whittaker, "High energy radiation grafting of fluoropolymers," Progress in Polymer Science, vol. 28, pp. 1355-1376, 2003.
31. T. R. Dargaville, G. A. George, D. J. T. Hill, and A. K. Whittaker, "An Investigation of the Thermal and Tensile Properties of PFA Following g-Radiolysis," Macromolecules, vol. 36, pp. 7132-7137, 2003.
32. T. R. Dargaville, G. A. George, D. J. T. Hill, U. Scheler, and A. K. Whittaker, "Cross-Linking of PFA by Electron Beam Irradiation," Macromolecules, vol. 36, pp. 7138-7142, 2003.
33. S. Devasahayam, D. J. T. Hill, and A. K. Whittaker, "G-values for scission and crosslinking on g-radiolysis of Ultem at 303 K," High Performance Polymers, vol. 15, pp. 259-267, 2003.
34. D. J. T. Hill, S. Mohajerani, A. K. Whittaker, and U. Scheler, "Chain scission and branching in irradiated poly(tetrafluoroethylene-co-hexafluoropropylene)," Polymer International, vol. 52, pp. 1725-1733, 2003.
35. D. J. T. Hill, K. J. Thurecht, and A. K. Whittaker, "A study of the radiation chemistry of poly(chlorotrifluoroethylene) by ESR spectroscopy," Radiation Physics and Chemistry, vol. 68, pp. 857-864, 2003.
36. D. J. T. Hill, K. J. Thurecht, and A. K. Whittaker, "New Structure Formation on g-irradiation of Poly(chlorotrifluoroethylene)," Radiation Physics and Chemistry, vol. 67, pp. 729-736, 2003.
37. M. Malak, D. J. T. Hill, and A. K. Whittaker, "Water sorption into poly[(2-hydroxyethyl methacrylate)-co-(1-vinyl-2-pyrrolidone)]at 310 K," Polymer International, vol. 52, pp. 1740-1748, 2003.
38. I. Brereton, S. Devasahayam, D. J. T. Hill, and A. K. Whittaker, "Towards identifying the new structures formed on the g-radiolysis of Ultem," Radiation Physics and Chemistry, vol. 69, pp. 65-77, 2004.
39. T. R. Dargaville, G. A. George, D. J. T. Hill, and A. K. Whittaker, "An Investigation of the Nitroxide-Mediated Preirradiation Grafting of Styrene onto PFA," Macromolecules, vol. 37, pp. 360-366, 2004.

40. D. J. T. Hill, and A. K. Whittaker, "radiation Chemistry of Polymers", Encyclopedia of Polymer Science and Technology, 2004, on-line edition.

41. Blakey, Idriss; George, Graeme A.; Hill, David J. T.; Liu, Heping; Rasoul, Firas; Whittaker, Andrew K.; Zimmerman, Paul. XPS and 19F NMR Study of the Photodegradation at 157 nm of Photolithographic-Grade Teflon AF Thin Films. Macromolecules; 2005; 38(10), 4050-4055.

42. Kresten L.C. Nielsen, David J.T. Hill, Kent A. Watson, John W. Connell, Shigetoshi Ikeda, Hisaaki Kudo, Andrew K. Whittaker, The Radiation Degradation of a Nanotube-Polyimide Nanocomposite, Polymer Degradation and Stability, (2008), 93(1), 169-175.

Collaborators

Prof. Clive Baldock – University of Sydney;
Dr. John Connell – NASA;
Prof. Hisaaki Kudo – Tokyo University

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