http://www.revmaterialeplastice.ro MATERIALE PLASTICE ♦54♦No. 3 ♦2017 589 Nanoaggregates and Selforganization Phenomena in Polyurethane Coumarine Film SILVIU GURLUI 1 *, ION SANDU 2,3 , NICANOR CIMPOESU 4 , VALENTIN POHOATA 1 , IOAN GABRIEL SANDU 3,4 , MITACHI STRAT 1 1 Alexandru Ioan Cuza University of Iasi, Faculty of Physics, 11, Carol I Blvd., 700506 Iasi, Romania 3 Alexandru Ioan Cuza University of Iasi, ARHEOINVEST Interdisciplinary Platform, 22 Carol I Blvd., 700506 Iasi, Romania 3 Romanian Inventors Forum, 3 Sf. Petru Movila St., 700089 Iasi, Romania 4 Gheorghe Asachi Technical University from Iasi, Faculty of Materials Science and Engineering, 41 Dimitrie Mangeron Blvd., 700050 Iasi, Romania The spectroscopic and photochemical properties of polyurethane coumarine (PUC) in solid state were investigated at room temperature under once-photon excitation. One photon induced photocycloaddition of PUC was investigated and the AFM and spectroscopic FTIR analysis confirmed dimer formation. The AFM analysis shows that the fotodimerization process occurs at the surface of polymer films. The polyurethane coumarine film on CaF 2 unirradiated and irradiated underline both the fotodimerization of the polymer films as well as the photoclevage of the polyurethane coumarin Kywords: polyurethane coumarin; photophysical properties; photochemical properties; selforganization phenomena; nanoaggregates Coumarins and many of its derivatives have important applications in biological and medical treatments. Perhaps of the greatest fundamental biochemical interest is the photo-sensitizing effect on human cells [1-5]. Analysis of photosensitive materials containing an aromatic fluorophore very sensitive to an external stimulus has a particular importance for obtaining new functional devices with applications in optoelectronics [6-7] . The stability of polymer micelles, which affects the stability of encapsulation of guest molecules, may be a crucial condition for some controlled delivery applications. Under these conditions the study of nature and of the nanoaggregate formation mechanisms in polymers containing fluorophores can provide information both about their structure and conformational properties of polymer in the form of films and solution [8-19]. The paper presents the photoplimerization and photocleavage properties of the polyurethane coumarin. The methods of atomic force microscopy and FTIR * email: sgurlui@uaic.ro spectroscopy are used. The results confirm the existence of the phenomena of nanoaggregation and self- organization in the coumarin polyurethane films. Experimental part The used solvents were found to be transparent and non-fluorescent in the range of excitation and fluorescence emission. All solvents [dimethylformamide (DMF), dimethyl sulf-oxide (DMSO), tetra hydro furan (THF)] (Merck reagent grade) were used without further purification. The polymer was prepared by the poly-addition reaction of classical poly (tetra methylene oxide) diol of molecular weight 2000, 4, 4 ‘-diphenylmethane diizicianat and N, Ndihidroxietilpiperazine, using the molar ratio 2:3:1. In the next step, the formed polymer was treated with bromine-methyl coumarin, to lead the polyurethane quaternized in proportion of 10%. The investigated polyurethane, the photopolymer block copolymer and the photocycloaddition of polyurethane coumarin side groups are given in table 1, together with the main spectral Table 1 THE CHEMICAL STRUCTURE AND SOME SPECTRAL PROPERTIES