Photoinduced heating of thin nitrogen-polymer films

E.A. Chernykh^a*, S.S. Kharintsev^a,b**, A.T. Edrisov^c***, D.P. Khrustalev^c****

^aKazan Federal University, Kazan, 420008 Russia

^bTatarstan Academy of Sciences, Institute of Applied Research, Kazan, 420111 Russia

^cNazarbayev University, Astana, 010000 Republic of Kazakhstan

 E-mail: *elenorchernykh@gmail.com,  **skharint@gmail.com, ***azamat.yedrissov@nu.edu.kz, ****khrustalev@bk.ru

Received December 11, 2017

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Abstract

In this work, the photo-induced heating of polymer films functionalized with azo-chromophore molecules has been studied for the first time. We have characterized the photoinduced heating of free-standing thin films with the use of scanning thermal microscopy with nanometer resolution. It has been shown that the film of 800 nm thickness being irradiated by resonant laser radiation (532 nm) and the power of 25 mW/cm² is heated by 1.7 K. Furthermore,a method has been introduced for determining the glass transition temperature of thin (< 100 nm) polymer films based on thermo-induced atomic force microscopy (thermal-assisted AFM). In the proposed approach, the change of the phase of oscillating AFM cantilever has been used to determine the glass transition temperature. An anomalous decrease in the glass transition temperature has been shown for both free-standing and supported azobenzene-functionalized polymeric thin films.

Keywords: atomic force microscopy, thin films, polymer films, glass transition temperature, photoinduced heating, azo-polymers, azo-chromophores

Acknowledgments. The study was supported by the Ministry of Education and Science of the Republic of Kazakhstan (project no. AP05132037).

Figure Captions

Fig. 1.  a) The layout diagram of the experiment on measuring the temperature of free-standing film;  b) the absorption spectrum of CFAO;  c) photoinduced heating of the detector with a thin CFAO film and without it upon the impact of laser radiation with the wave length of 532 and 632.8 nm (the figure shows light intensity, mW/cm²).

Fig. 2.  a) The graph showing the dependence of the oscillating phase of the cantilever on the sample temperature for films with the thickness of 20 and 200 nm;  b) the graph showing the dependence of the temperature of glass transition for polymer films on base glass and cantilever films on their thickness.

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For   citation:  Chernykh  E.A.,  Kharintsev  S.S.,  Edrisov  A.T.,  Khrustalev  D.P. Photoinduced  heating  of  thin  nitrogen-polymer  films.  Uchenye  Zapiski  Kazanskogo Universiteta. Seriya Fiziko-Matematicheskie Nauki, 2018, vol. 160, no. 1, pp. 145–153. (In Russian)

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