Nguyen Van Thuan, Tran Vinh Son, Tran Quang Trung, Tran Thi Thao, Nguyen Nang Dinh

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Laser beam diffraction by a patterned surface has been investigated theoretically and experimentally for the determination of the thermal expansion coefficient (a) of polymeric materials. By tracking the deviation of the first order diffraction mode from surface-patterned polymers, expansion coefficients in a range 10-7 to 10-4 K-1 can be measured by temperature changes less than 100 oC. A set-up of laser diffraction (SLD) was made, using a He-Ne laser (l = 632.8 nm) and thin film casting technique. The results of measurements on the SLD system for polymers like PVK polycarbonate, PDMS, organic complex (chitosan) and conducting polymer (P3HT) showed that SLD technique can be applied to determine thermal expansion coefficients of different polymeric materials with a considerably small volume. Especially, the fact that a of P3HT-composite films was found to be much lower than that of the pure P3HT suggests a potential application of polymeric composites for organic devices working at elevated temperature, for organic solar cells (OSC) in particular.

Keywords: Laser beam diffraction; thermal expansion; diffraction grating; polymer.


[1] B. D. Malhotra, Handbook of Polymers in Electronics, Rapra Technology Ltd., Shawbury, Shrewsbury, Shropshire, SY4 4NR, UK, 2002.
[2] J. S. Salafsky, Phys. Rev. B 59 (1999) 10885.
[3] V. M. Burlakov, K. Kawata, H. E. Assender, G. A. D. Briggs, A. Ruseckas, I. D. W. Samuel, Phys. Rev. B 72 (2005), 075206.
[4] A. Petrella, M. Tamborra, P. D. Cozzoli, M. L. Curri, M. Striccoli, P. Cosma, G. M. Farinola, F. Babudri, F. Naso, A. Agostiano, Thin Solid Films 451/452 (2004) 64.
[5] S. Bhattacharyya, A. Patra, Bull. Mater. Sci. 35 (2012) 719.
[6] Tran Thi Thao, Do Ngoc Chung, Nguyen Nang Dinh, Vo-Van Truong, Comm. in Phys. 24 (2014) No. 3S1, 22-28.
[7] R. Scholl, B. W. Liby, Manhattan College, Riverdale, NY 2009 The Physics Teacher, Vol. 47.
[8] H. Watanabe, N. Yamada, M. Okaji, Inter J. of Thermophysics 25 (2004) 221.
[10] W. W. Tooley, S. Feghhi, S. J. Han, J. Wang, N. J. Sniadecki, J. Micromech Microeng (IOP publishing) 21 (2011) 054013.
[11] P. A. Do, M. Touaibia, A. Haché, App. Optics, 52 (2013) No. 24, 5979.
[14] A. Chandra, W. H. Meyer, A. Best, A. Hanewald, G. Wegner, Macromol. Mater. & Eng. 292 (2007) No. 3, 295.